A Stealthy Motor To Cycle Fast

My suggestion that low power assist is all you want received support and scepticism in a discussion at Endless Sphere. Having formed the view you don't need much help to cycle fast I'm wondering how it can best be done and wish to select a motor and model some scenarios.

What's Out There?

The Gruber Assist, shown in Figure 1, provides a high cost, low power solution that is visually stealthy enough for Fabian Cancellara to be accused of using it during Paris Roubaix and the Tour of Flanders but too noisy for it to be true. Detailed performance information is unavailable but reviews are generally enthusiastic. Negatives reported are 50% efficiency and simple on/off control.

Figure 1: The Gruber Assist is a stealthy 100W output motor that resides in the seat tube.

Bosch mid drive motors have integrated control and display, use pedal torque sensors and offer several operation modes. They appear close to ideal but I'd prefer a mobile phone as the display device, at 4 kg they are heavier than some alternatives, they need a frame designed to fit, and the control algorithms are not published and can't be altered or integrated into cycling tracking applications. Some other mid drive e-bikes are available, like the low cost Aseako/Zoco Rossa.

Friction drive, shown in Figure 2, provides an alternative using small, high speed RC motors but the transmission losses driving the tyre are probably high.

Figure 2: A lightweight friction drive.

Other alternatives are hub drives which are either direct drive or the lighter less powerful geared motors.

Albert van Dalen has done an investigation of bike motors that focuses on efficiency and compares them on weight vs rated power.

Silence Is Beautiful

Modern bicycle motors are brushless DC with six step trapezoidal control explained in this video. Controllers are cheap, from about US$18, but produce motor torque ripple that is often audible. For little additional expense, controllers could use better algorithms to eliminate noise. Figure 3 shows an example of noise reduction in a direct drive hub motor using sinusoidal control.

Figure 3: An example of noise reduction achieved in a direct drive hub motor with sinusoidal control.

There seems to be a gap in the market as only trapezoidal controllers are commercially available.

Torque ripple is avoided by rotating the magnetic flux vector so that it is always perpendicular the magnetic flux vector of the spinning magnets which can be achieved with field oriented control. In contrast to applications like washing machines, torque loads on e-bike motors vary slowly and typical e-bike motors produce sinusoidal back EMFs¹. Under these circumstances the simpler sinusoidal control generates the same output as field oriented control.

Field oriented control is often suggested as a means of increasing motor efficiency. In a simulation Johan Astrom² found only a marginal efficiency improvement with an optimal control scheme over trapezoidal control for a 375 W motor because a non perpendicular magnetic vector mostly acts to store and release energy in different parts of the cycle.

Geared motors can also produce gear noise. The lightweight Tongxin/Keyde hub motor uses rollers rather than gears which is reported as effective for motor silencing but may increase gearbox friction losses.

Regulation

Previously, unregistered electric bikes in Australia were required to "be able to prove that the motor output is not more than 200 watts" but there were no restrictions on how that power could be used. Recently the European standard EN 15194:2009 was introduced as an alternative which allows motors rated up to 250 watts continuous while requiring riders to pedal at speeds above 6 km/h (clause 4.2.4.3.1) to receive assistance and restricting assistance to speeds below 25 km/h. With the usual controllers, a 200 W maximum means much lower power over most of the operating range, so most Australian electric bikes probably exceeded the previous requirement. For those bikes that didn't, the change from "not more than" to "continuous" means motors are potentially a lot more powerful than a 50 W increase would imply. The continuous motor rating power is only loosely related to instantaneous power as shown in figure 4.

Figure 4: The rated power is at the intersection of the rated speed and rated torque lines. The position of the sloping line is determined by the rated voltage. The rated values are nominated rather than physical properties of the motor.

The continuous motor rating is a value assigned by the manufacturer at which the motor is guaranteed not to exceed temperature specifications as defined in IEC 60034-1 clause 8.10 - Limits of temperature and of temperature rise.  As an example, Bosch mid drive motors, rated at 250 W, have input power measured in figure 5, above 600 W for considerable periods while climbing a 5.5% grade pedalling at speeds around 23 km/h prompting reviewers to conclude the "Bosch mid drive feels as zippy and fast as 750-watt hub motor bikes."

Figure 5: Bosch mid drive input power while climbing a 5.5% grade pedalling at speeds around 23 km/h. Output power is probably about 75% of input power.  

Fast cyclists exceed speeds of 25 km/h, so incapable riders seeking to keep up will need assist at speeds above 25 km/h. EN 15194:2009 clause 4.2.6.2.2 c) specifies that the maximum speed test should be conducted at 1.25 times the rated speed, therefore some assist can actually be provided up to 31 km/h and still comply. This is above the speeds the average rider can maintain on flat ground but far short of the 41.6 km/h Chris Horner maintained over 172 km in the sample ride. Bosch overcome this limitation by also selling a "Drive Unit 45" version which lifts the rated cut off speed to 45 km/h.

Motor Selection

The Cute Q-85SX/GBK-85F, detailed in this drawing was suggested by Albert van Dalen. It is nominally 1.6 kg but was tested as 1.84 kg including electrical cable. He doesn't consider a lighter, nominally 1.2 kg motor in the Cute drawing, which may not be purchasable, and he chose the Cute over the Tongxin/Keyde which is nominally 200 gm lighter at 1.4 kg as the Cute was more easily acquired³. Accepting his motor recommendation, Albert's motor testing data can be used to model e-bike scenarios.

Motor Model

Albert conducted a carefully documented motor investigation and dynamometer test from which he constructed a motor  model. The dynamometer data, in figure 6, shows evidence of saturation beyond torques of 20 Nm, corresponding to a motor current of 12.9 amps, so a model is only valid for torques <20 Nm. Saturation could be avoided with more iron, but space is limited so that would necessitate less copper, increasing electrical resistance and reducing motor efficiency at torques <20 Nm. To avoid rapidly increasing inefficiency and overheating, this motor should be operated at currents less than 12.9 amps, though higher currents are sometimes used. This matches the Ku63 controller which limits current to 12 to 12.85 amps.

Figure 6: Dynamometer test data

Albert measured motor winding resistance as R  ≈ 0.307 Ω (stated as mΩ but intended as Ω) but elsewhere he calculated R = 0.77 Ω which is a substantial difference.  He accounts for the difference as gearbox friction and uses the measured value in his model, however the relationship:- Vo = (I * R) + (ω * Ke) which is expressed in Albert's notation as U = (I * R) + (ω * k) is independent of gearbox friction losses. Rearranging to k = (U - I * R)/ω, the motor constant (k) can then be plotted against rotational speed (ω) of the wheel using the dynamometer test data as shown in Figure 7.

Figure 7: Motor constant k versus ω with R = 0.307 Ω. Slope should be zero.

Adjusting to R = 0.75 so that the slope of a linear estimate of k = 0 gives the result in Figure 8.

Figure 8: Motor constant k versus ω with R = 0.754 Ω. Mean value of k = 1.55.  Note: The y axis scale is different to figure 7.  

The inconsistency of the estimated resistance with the measured resistance is a mystery which would be good to resolve. The estimated resistance is used for the motor model.

Torque is measured after the gearbox and is reduced by friction losses as shown in figure 9.

Figure 9: Different types of friction losses sum to the total friction loss. Friction at velocities near zero are ignored as  very low speed behaviour is not modelled.  

The losses in torque due to viscous and coulomb friction in the gearbox and motor can be modelled as:-
T = (Ts - Cv * ωs - Cc* Ts) * GR
where:-
T = wheel torque (Nm)
Ts = torque before the gearbox (Nm)
ωs = motor speed before gear box (rad/sec)
Cv = viscous friction coefficient
Cc = coulomb friction coefficient
GR = gearbox gear ratio

Combining with the motor equation:-
Ts = ks * i
where ks = motor constant before gear box (Nm/A)
and:-
k = GR * ks
where k = motor constant at the wheel (Nm/A)
and rearranging gives:-
k = (T + Cv  * ω) / (i *  (1 - Cc))

Figure 10: Motor constant k versus motor speed ω with R = 0.754 Ω. Mean value of k = 1.55.

Values for Cv and Cc can be found numerically to best match k to the previously determined value while minimising the slope of a linear estimate of k as shown in figure 10.
Resulting in:-
Cv = 0.033
Cc = 0 which means Cc can be ignored in the motor model.

The patterns evident in figure 10 suggest the model is not fully representative of the motors behaviour but the resultant errors are acceptable and being determined from large numbers of independent measurements should be considerably less than the estimated 5% error for individual measurements.

The parameters R = 0.754, k = 1.55 and Cv = 0.033 can be used to construct the motor model which can then be combined with the previous bike model and used for simulations of electric bike scenarios in a future post.

References

1. Renesas Application Note: 180 Degree Sinusoidal Motor Control  Based on this document; pg 3; " As many brushless motors have sinusoidal BEMF ..., it is possible to match these motors with a sinusoidal driving voltage."
2. Johan Astrom;  Investigation of Issues Related to Electrical Efficiency Improvements of Pump and Fan Drives in Buildings; PhD Thesis; Department of Energy and Environment, Chalmers University Of Technology, G¨oteborg, Sweden 2011; Figure 6.23 pg 97;  The graph shows marginal improvement, about 3% maximum in part of the efficiency/load curve with an optimal control scheme over standard BLDC motor control for a 375W motor. 
3. Personal correspondence.

What Would It Take To Cycle Fast When You Can't?

Working with pro cyclists has inspired me to cycle more. However, I'd like it to be easier when I'm weary or climbing a hill and I'd like to keep up with the guy in front. Less body weight and increased aerobic fitness would help but no amount of training could get me up with the young guys. I don't want a motorbike but some stealthy assistance would be nice.

I've trialled electric bikes from Switched On Cycles for a couple of weeks and the experience is good but not ideal.

Figure 1 - A bike trialled with a rear hub motor. A front wheel drive bicycle was also trialled that had a Bafang, nominally 250 watt motor powered from a 36 volt battery.

The bikes work well for a commuter seeking to journey with minimal effort but are non optimal for my ambitions. The motor was quiet but audible, I'd like quieter if possible. I tried using the throttle modestly but its hard to sense the level of assist and power at these levels is as addictive as heroin. A little bit feels good so you want more and taking it away causes pain. On the flat, the motor can get the bike along at a reasonable speed without pedalling so the temptation to slack is as hard to resist as a good snack. Exerting the willpower to ride hard causes the power to fade as the speed increases so that I still can't catch the guy in front. Pedalling up a modest hill though is much easier and climbing Black Mountain at average grades of 9% I can pass the young guys. Surprisingly though, I have to pedal hard and at the top I notice the motor is sizzling.

I want a bike as close to a normal road bike as possible, that is silent, has a motor battery combination that is as light and unobtrusive as possible and doesn't run out of puff until I complete the ride. It's also apparent that whatever well planned strategies I might have for power management I behave like a junkie. My addiction, once I'm gasping for breath and the heart is pounding will cause me to abandon good intentions and seek immediate relief if all it requires is to twist the throttle.

Estimating Power Needs

Using a standard bicycle power model for a flat road and with my parameters estimated as:-

Rolling resistance Cr				0.004
Air density ρ				1.225	[kg/m²]
Drag coefficient				1
Reference area				0.5	[m²]
Transmission eff.				97	[%]

gives me the result in Figure 2.

Figure 2 - My power vs speed model for a flat road and a windless day.

Above 15 km/h it can be seen most power (Pdrag) is consumed pushing air out of the way and air drag increases with velocity cubed so that it quickly becomes dominant. A person weighing 82 kg produces about 95 watts to walk at a brisk 4.8 km/h and 57 watts at a more leisurely 3.2 km/h, according to table 1 of "The Energy Cost of Walking" after applying the suggested thermal efficiency of 30%. From Figure 2 this will get a bike along at 18 km/h on level ground.

From Table 1 I can average 24 km/h on a good day over a fairly flat 5.2 km section of a 36 km ride around Lake Burley Griffin which, from Figure 2 equates to about 120 watts. The estimate of reference area and drag coefficient is crude so it is probably +/- 15 watts  of the true value but its close enough for some comparisons.

Rank	Date	Speed (km/h)
1	Nov 25, 2012	25.1
2	Dec 2, 2012	24.8
3	Nov 29, 2012	23.9
4	Dec 16, 2012	23.8
5	Nov 18, 2012	23.5
6	Nov 24, 2012	23.2
7	Nov 30, 2012	23
8	Dec 3, 2012	22.9
9	Nov 26, 2012	22.3
10	Nov 23, 2012	22.3
11	Nov 14, 2012	21.8
12	Nov 13, 2012	19.6

Table 1 - Speeds over the same fairly flat section. 
The fastest rides might have benefited from a favourable breeze.

With a 500 watt motor the bike could get to 41 km/h but adding in my best average effort, would get a barely noticeable 3 km/h more. I doubt I could raise the motivation to do it. So at 500 watts I would already be riding a motorbike, albeit a dissatisfying one. It requires something like the Stealth Bomber at 4.5 kW to satisfy the power craving and by then the pedals are just for decoration. As for our reaction to artificial humans, it seems the level of satisfaction from extra power suffers an uncanny valley.

Chris Horner's 172 km ride in stage 4 of the 2011 Tour De France has been published and analysed.

Figure 3 - Chris Horner's ride data from stage 4 of the 2011 Tour de France

He averaged 215 watts for the whole stage, so a mere 95 watts of assist could put me in the peloton with Chris. For the final 25 km he managed 318 watts so I'd need 200 watts of assist to stick with him there but its still not much. He also managed 502 watts for 2 minutes and peaked at 710 watts. I could up the power a bit for 2 minutes too but I'd need some significant extra assist to match Chris and a 10 second sprint finish, which Chris didn't do in stage 4, would crush me. Chris also used his power more efficiently than the model for me predicts, averaging 41.6 km/h. He does this by riding most of the race on the wheel of other riders to reduce air drag and may (or may not) have had a tailwind. He also has a small cross sectional area maintained by a good pose and the small volume needed for his weight of just 64 kg, including the bike. Low weight  helps hugely on the hills as well.

I'm not aiming to match Chris in all circumstances but an extra 100 - 150 watts peaking at 250 - 350 watts of silent, light weight electric power, strategically provided by an algorithm I can't abuse would put me in the ball park. Much more than that would put me well ahead of the Tour de France field but leave me dissatisfied in the uncanny valley on a gutless motorbike.

Update

I sought feedback on this article at Endless-Sphere and there was a substantial debate, which I've summarised here.

 NeilP spoke for many:-

NeilP wrote:

Ken Taylor wrote:Do experienced ebike riders always get more satisfaction from more power?

 YES YES YES YES YES!!! 

and some like:-

maydaverave wrote:I have a low power 1000 watt bike. Its a great commuter for my small town and as time goes by I find myself going slower on it.

had a different definition of low power than I'd intended.

Kraeuterbutter at viewtopic.php?f=28&t=37785#p587951 is somewhat sceptical of the power requirements of Endless Sphere aficionados. 

However, there was some with plenty of experience of high power bikes who saw merit in low power bikes which I'd define as not more than 2-3 times more power than pedalling. For example:-

chvidgov.bc.ca wrote:I've experienced this when I recently put a "Cute" motor on a nice light aluminum framed roadbike.... I've been very happy with the very bikelike experience

Jeremy Harris wrote:I started out with a fair bit of power, but find that the ebike I like best, and ride most, is the light one with the low power motor. The reasons aren't that straightforward, I think. 

melodious wrote:....That article does have merit. A bike w/motor takes the physicality of the experience away. I'm really hesitant to taint my last true bike into a motorized vehicle. 

Some commented on the psychology of power:- 

dogman wrote:A great deal depends on the goals of your ride. As goals change, the mental attitude changes.

rocwandrer having never ridden an e-bike felt unqualified to add to the discussion but pointed out that:-

rocwandrer wrote:The vast majority of my riding time is purely recreational, with the destination being the departure point.

which is probably pretty common and my favourite version of cycling. After presenting the reasons he claims:-

rocwandrer wrote:If the benefit from adding pedal power does not FEEL proportionate to the effort, it is much harder to put in that effort....That all matches with Ken's hypothesis that if there is enough power on tap with the electric assist to make the human contribution feel less critical, or to make the return for extra effort feel too small, it is will psychologically difficult to even acknowledge that there is more in reserve in the human power side's controller.

Innovative Value Transfer Systems For Government

There is potential to improve government transfer payments through innovative payment systems that make it easier to issue funds, spend the benefit and automatically capture the accounting information. Such a system could be used for government transfer payments for a wide variety of purposes.
Advantages include:-

• Recipients would use a common method of receiving and spending many different payment types.
• A recipient would be immediately aware of having received the benefit and the value of the benefit.
• A controlled market could be created to capture the advantages of market economies while restricting products and services to the types intended.
• The funds associated with the benefit are not spent until the service provider claims from the government.
• Transfer payments not consumed by the recipient will automatically evaporate. 

Government Transfer Payments

A transfer payment is made without any exchange of goods or services. Examples of transfer payments include welfare (financial aid), social security and government making subsidies for certain businesses. 

The Henry Tax Review [1]  considered transfer payments and concluded "A coordinated approach should extend to the consideration of housing assistance, access to aged care and transfers that are tied to expenditure on other goods and services. A coordinated approach would support greater equity between transfer recipients, reduce the inherent disincentives to work created by taxes and transfers and underpin a better client experience of the tax and transfer system." The  tax review describes several classes of transfer payments:-

• family-related payments 
• child care, housing assistance
• transfers tied to goods and services
• aged care

Transfer payments are intended to achieve a social purpose. Those tied most narrowly are where "governments also provide other transfers in the form of concessions or payments that are linked to the purchase, or supply, of a particular good or service"[1] but others including childcare,  housing assistance and some aged care services are also intended for quite narrow purposes. Governments currently employ a variety of methods to ensure payments are directed towards the desired purpose.

Innovative Value Transfer Systems

Innovative value transfer systems have been slow to develop in the information age and many have failed. "While electronic money has been an interesting problem for cryptography .., to date, the use of e-money has been relatively low-scale."  Probably the most widely used  information age payment system, Paypal is grafted on to previously existing card payment networks and provides barely distinguishable services.

Strategic Review of Innovation in the Payments System - RBA

The Australian Reserve Bank has an interest in fostering innovation in Australian payment systems and government transfer payments should be part of that innovation.  The recently completed Strategic Review of Innovation in the Payments System had "the objective of identifying areas in which innovation in the Australian payments system could be fostered through more effective cooperation between stakeholders and regulators."[2]

The review sees "the potential to unlock significant future innovation, resulting in ongoing improvements to the efficiency of the payments system.... the Board intends to be more proactive in setting out strategic objectives for the payments system, that is, its expectations for the services that the payments system should be able to offer in the future." 

The review considers the key attributes of payment systems to be:-

• Timeliness
• Accessibility
• Ease of use
• Ease of integration with other processes
• Safety and reliability

As government transfer payments represent an important component of the payment system there is an opportunity to influence the direction of innovation in partnership with commercial partners.

Fungible Value

In standard payment systems value is fungible, meaning it is transferable for any purpose, but many government transfer payments are intended for a particular purpose and it is in this area that innovative payment systems can contribute. An innovative payment system could be used to create a closed economy where a payment can only be made to approved suppliers for intended purposes. Within that closed economy normal trading can occur. This is ideal for government transfers in the form of concessions or payments that are intended for the purchase, or supply, of a particular class of good or service e.g. laptops for school aged children.

An Innovative Example - Bitcoin

Bitcoin is a new payment system that is often though of as libertarian but it has characteristics that could be utilised for government transfer payments. Variants of Bitcoin, known as alt-coins could be used for transfer payments or aspects copied in alternative value transfer mechanisms. Most importantly, Bitcoin has been shown to work, is in active use and has a suite of tools and services under development. A level of granularity in transaction data and payment flows down to individual items or services is achievable and separate alt-coin currencies can be generated for each class of transfer payment. It is at least useful for exploring what is possible and the desirable characteristics of value transfer systems.

Characteristics Of Bitcoin

Simple To Use

The underlying mechanism is invisible to users making it simple to understand and use. It usually requires an internet connection and payment device which can be a PC application,  a web browser app or smart phone app. However, paper based transactions are also possible.

A person is presented with a bill, can use their smart phone camera to read the bill and can authorise the transaction with a key press. In the future it is likely that, using OpenPay, a consumer will be able to spend bitcoins at any merchant that is able to accept Visa or Mastercard.

Preserves Privacy

Because transactions are broadcast to the entire network, they are inherently public. Privacy is maintained through anonymous account numbers.

Simple Accounting

Transaction data is captured as part of the transaction without requiring additional reporting. If the mapping is known, transactions can be traced from account numbers to individuals. In a government transfer system the government issuer would create that mapping.

Others

Bitcoin is an innovative payment system gaining traction but there are many others as described in the Electronic Money Wikipedia article and the RBA's Strategic Review[2] provides a model for real-time retail payment and settlement hubs which includes a list of desirable characteristics.

Current Mechanisms For Transfer Payments

Direct Payments

Most direct payments are not linked to the purchase, or supply, of a particular good or service and work well with current payment systems.

The BasicsCard

The BasicsCard is a stored value EFTPOS card provided by the Department of Human Services that allows purchases for authorised items from authorised merchants.

The merchant enforces the restriction to authorised items and the EFTPOS system can't create an audit trail to verify this restriction. It has attracted some controversy but Jenny Macklin, the Minister for Families, advises "We've had it now operating for a few years; we know that it's helpful. The individual stories are very positive." It's proven there is a desire for government transfer payments to be directed to particular areas but the BasicsCard is limited to the options provided by the existing EFTPOS system and is not suitable for many forms of transfer payment, for example Renewable Energy Certificates. Innovative value transfer technologies can extend the BasicsCard concept.

Tax Benefits

Some transfer payments are claimed through the tax return. This method is cumbersome, creates a delay between incurring the expense and claiming the benefit and puts a substantial administrative burden on claimants. An example is the Schoolkids Bonus formerly known as the Education Tax Refund. It is intended for expenses such as uniforms, books, school excursions, stationery and other costs like music lessons and sports registration fees. Previously, proof of expenditure was required by claimants but to reduce the administrative burden the requirement was removed so that the benefit is only notionally provided for the intended purpose. Innovative value transfer technologies could restore the original concept of directing the payment to the intended purpose and make the benefit available in an attractive form that can be spent rather than received as a refund.

Direct Provision of Goods and Services

Sometimes governments directly provide goods and services when a superior outcome could be achieved by a transfer payment combined with market mechanisms. An excellent example is the laptops for schools program. Some students never got a machine. The machines supplied required tendering and administrative processes that introduced massive delays. There was a transfer from parents to government of the burden of ensuring responsible use and the $1,000 per machine supplied by the federal government proved insufficient to cover the machine and program costs so that in extreme cases parents were asked to contribute more per machine than the cost of a similar machine from a retailer. Use of the existing supply chain with an innovative transfer payment solution would have achieved a better result.

Voucher Systems

Renewable Energy Certificates (RECs) are a tradeable voucher for encouraging investment in green energy initiatives. "Eligible renewable energy sources are entitled to create certificates based on the amount of electricity they produce or displace. These certificates can be created in the REC Registry and sold to buyers."

These vouchers are quite different to payment systems like the BasicsCard but to an innovative value transfer system RECs would appear as just another value type and be traded in the same way a beneficiary trades their laptops for schools benefit. The trading system would automatically perform the function of the REC registry.

References

1. Australia's Future Tax System Review; Chapter 9: The transfer system; Australian Government; May 2010.
2. Strategic Review of Innovation in the Payments System: Conclusions
June 2012; Reserve Bank of Australia

Climbing Gunung Batur While Avoiding Trouble

I'm fond of ascending peaks. In 1980 my first peak outside Australia and first live volcano was Gunung (meaning mountain) Batur, Kintamani, Bali. Unlike nearby Gunung Agung, which is tough, it is a modest peak with a five kilometre ascent that takes two to three hours. That makes it great for a  group  looking for some adventure bonding in which everyone can participate. Strenuous enough to be memorable but not too difficult. This easy access is not ideal for the guiding profession so, on Batur, they counter with a hard sell. Locals don't use guides and while foreign visitors often like to be guided, many would prefer to climb on their own. Guideless climbers still need directions, particularly as Batur is usually climbed at night with the aim of being on the summit for the sunrise.

The Route

There are multiple routes up the cone. The most used originates from a car park and from there proceeds up through the village, ascending the mountain by one route and descending by another. 3.00am to 4.00am is a good starting time to view the dawn from the summit.

Animation of the most common route up Batur and some attractions along the way.

The guiding office is near the car park and anyone starting from here without a guide will be accosted by the guiding enforcers. Climbers starting from elsewhere may be able to avoid this confrontation.

If you are climbing at night without a guide you will need a route map as you will cross many paths leading elsewhere and sometimes the correct path is the least obvious.

View Climbing Gunung Batur in a larger map with icon legends and route notes. The second icon is the carpark at the start of the climb and the first is at hotel Volcano III where we commenced.

I recorded the route with My Tracks and it is available as a GPX file for import into your mapping app. Most people walk around the rim but some of our party didn't want to go further after reaching the summit.

Alternatively, you could follow the torch light of another guided group but that may lead to trouble and is poor form if you have refused guiding services.

Then and Now

Despite being a modest climb, my first ascent in 1980 seemed quite an adventure. I had no idea Batur was there until I arrived on a trail bike after traversing roads impassable to cars.

The road close to Toya Bungkah in 1980 with the village in the background.
Image:  Around Gunung Batur - in the past  set.

Heading towards Toya Bungkah probably close to  Kedisan, the village at the bottom of the descent into the caldera in 1983.
Image: Batur - Change From 1967 Until Now gallery.

The road near Toya Bungkah in 2009, still nothing special,  but much improved.  Nearby roads are built to a much lower standard and are still frequently impassable.
Image: Batur and Trunyan in 2009  set. 

The village was recent. In 1967 it had not existed and in 1980 a warung was the sole commercial establishment.

This warung, typical of the style in Bali at that time, was the only commercial establishment in Toya Bungkah in 1980. I slept in this guys home.
Image:  Around Gunung Batur - in the past  set.

It was an obviously poor village with the children spending their days tending to cows that aren't kept there any more.

These kids spent their days cutting grass for the cows and didn't attend school. I don't know if all the kids go to school today but there are plenty of people here in their twenties who didn't and weren't taught to read.
Image:  Around Gunung Batur - in the past  set.

Today Toya Bungkah looks reasonably affluent but the surrounding area remains poorer than you will see elsewhere in Bali.

Apart from the climb, the principal attraction of Toya Bungkah is the hot springs which the locals use as a communal bath. The public facility was pretty good in 1983 but has been developed and privatised so that there are now several facilities exclusively for tourists, some quite expensive. There is one new facility next to the car park that is free for Toya Bungkah residents and Rp50K for all visitors including Balinese.

The hot springs were a well constructed public facility in 1983.
Image: Batur - Change From 1967 Until Now gallery.

The privatised facility on the site of the previous public facility, US$16 for foreigners and Rp40K for Indonesians. Toya Bungkah residents don't go here.
Image: Batur - Change From 1967 Until Now gallery.

The Ayu hot springs facility, with accommodation and Bali's only camping ground. Upmarket and exclusively for tourists and the wealthy.
Image: Batur - Change From 1967 Until Now gallery.

With the climbing team at the facility near the car park. Free for Toya Bungkah residents and Rp50K for everyone else with a welcome drink.
Image: Climbing Gunung Batur  set.

In 1980, I climbed from around 3.00am to view the sunset from the summit which I've repeated several times since, on most occasions without a camera.

Ascending Batur in 1980
Image:  Around Gunung Batur - in the past  set.

Batur in 2005
Image: Gunung Batur Climb  set.

Near the summit in 2012 with children not much younger than I  was on that first climb.
Image: Climbing Gunung Batur  set.

There was no warung at the summit in 1980 but there was in 2004.

Climbers resting at the summit warung in 2004.
Image: Gunung Batur Climb  set.

Our party at the summit warung in 2012.
Image: Climbing Gunung Batur  set.

Across the lake is Trunyan.

It is a long way to the shore and I found this hollowed out log unstable and scary. Operating the camera while expecting to be in the water at any moment was tricky. You can drive on a rough track to Trunyan now but still need a boat to get the last few hundred metres to the cemetery.
Image:  Around Gunung Batur - in the past  set.

In 1980 it's bizarre cemetery had seemed exotic, though a bit unsavoury. Most climbers don't go there but lots of tour groups do from the wharf in Kedisan. I went back recently, to see what's changed and it's not a lot. Even in 1980, charging visitors to ogle grandmas remains was an income source for Trunyan.

Sky burial at Trunyan cemetery in 1980
Image:  Around Gunung Batur - in the past  set.

It hadn't changed much in 2009
Image: Batur and Trunyan in 2009  set.

Avoiding Trouble

It's easiest to pay up. Most climbers are brought directly from Ubud with the 40km drive being traversed in well under an hour when travelled in the early hours of the morning. A guide will be included in the package. You climb, swim and return with only pleasant experiences but are a little divorced from the locals. If you sleep nearby, particularly if you stay a few days, you will get a more grounded experience. This can be confronting as there is poverty and hassling, but you will see a different side of Bali with many people I've spoken to around the caldera claiming never to have been as far as Denpasar.

For the climb you will be strongly encouraged to hire a guide. It may seem compulsory but it isn't and lots don't. We checked in at the police station in Penelokan before descending into the caldera and checked back out on departure which my local colleague said was the norm though I'd never done this previously or heard of anyone anyone else doing it either.  Keen for reassurance from the police, we were also advised we couldn't be forced to hire a guide even when climbing with bule.

The Problem Is Widely Known

Batur rates as Number 4 on a  list of the Top 5 worst tourist rip - offs around Asia which states "Mount Organized-tourist-extortion is a good name for it." The  Jakarta Post reports "Anecdotal evidence says episodes such as these have been occurring around Kintamani and Lake Batur for some time, shaking the foundations of an important economic stream – tourism – for the region." and Trip Advisor documents some confrontations.

It's Been That Way For A Long Time

While I found Toya Bungkah pleasant in 1980 the guy that took me across to Trunyan kept telling me he feared extortion at Trunyan. This is is consistent with a quote from pg 19 of Custodians of the Sacred Mountain; Thomas A. Reuter; University of Hawai‘i Press; 2002; Travelers’ testimonies warn that local men may extort money from passengers by rocking their shaky boats as they ferry them across the lake. Authors of tourist guide books, who generally propagate romantic visions of smiling Balinese, have propagated the image problem of the hill people by characterizing them as “hostile, scruffy hustlers” (Winterton 1989:157–158) and as a potential “hassle” to those wishing to enjoy the natural beauty of their mountain home (Darling 1990:156).

"Ever tried walking up Mt. Batur alone? Try it and you'll get extorted by machete-wielding locals that demand you pay them $50 to be a guide." reports one climber from July 2004 showing it's not a recent phenomenon.

It's Economically Based

No one likes extortion (essentially taxation by non government entities), but it's most common in exploitative social systems when governance is weak. Modern China is sometimes described as a kleptocracy and under Suharto this was an apt description of Indonesia which weakens government authority. While Indonesia has been rapidly changing, these are strong traditions extending back to Dutch rule and they are more obvious in Batur than some other places. Apart from natural beauty, the area has limited resources and a long history of exploitation as discussed in Custodians of the Sacred Mountain; Thomas A. Reuter; University of Hawai‘i Press; 2002. This leads to distrust of authority and widespread opposition to taking advantage of opportunities like geothermal energy which will impact many but from which only a few elite are likely to benefit. The best assets are privatised by the politically influential and the poor barely get by labouring at agriculture. The only ways to escape hardship are to leave or exploit and with the best assets already taken, only services remain.

Many tourists will pay sums for half a days guiding that would otherwise require several weeks of agricultural toil to earn. Others stay away. In the absence of strong governance, groups emerge to capture the opportunity and without official authority, ultimately resort to stand over tactics to get their way. This is the environment that has bred the guiding cartel whose members can expect to do well as long as the monopoly can be maintained. One guide told me they have 63 members and work is divided amongst the members with each guide going to the bottom of  the list after each job. My informant said they averaged 20 climbers a day. While pricing is variable, they have strong pricing discipline, in my case, only dropping the guiding offer to Rp280,000 after things had become so unpleasant that hiring a guide at any price was unlikely. This can only be possible when they are effective in suppressing competition.

Batur's climbers are a mere quarter of 1 percent of Bali's visitors of 2.8 million in 2011. Guides from elsewhere will usually bring tourists only as far as Kintamani for the view from the caldera rim and will not offer the climbing opportunity. The road into the caldera is tough on their vehicles, so much so that I've known drivers to refuse the descent, and they are not keen to share guiding revenue with their colleagues in Toya Bungkah. While much effort goes into maximising revenue from those that turn up, there is little obvious effort on promoting the climb. Climbing is not everyone's thing but there is surely an opportunity to increase Batur's current visitor numbers. One tourist in a hundred ought to be easy. Working against that is the community inequality, coercion and distrust of government that makes it difficult to achieve more cooperation and investment in shared infrastructure, particularly roads, that would be required to attract large visitor numbers. The guiding association's ambition of Batur being an upmarket experience, is consistent with Governor Pastikas view that Bali should be an expensive destination but it is incongruous for the opulence of  the Ayu resort to be in stark contrast with the poor roads, poor infrastructure and obvious poverty over the fence.

With electricity and good mobile phone/internet reception Toya Bungkah is already not that weird "other world" I experienced in 1980 but increased development would mean losing some of the current atmosphere in the same way as Kuta has lost the atmosphere it had in 1980, as visitor numbers increased. Locals would welcome better roads and increased opportunities. Most visitors coming up for the day from Ubud probably wouldn't notice what was lost. While Kuta sadly destroyed much of its natural beauty as it developed a different sort of magic has emerged from the mayhem and the Kintamani region could develop its own different sort of magic and even maintain it's awesome natural assets.

The Positives

In 1980 when I first visited, Batur was pristine, probably because visitation was infrequent. On intermediate trips it was a free for all, covered in rubbish. Today it is clean, neat and not overbuilt. Someone must be responsible for this improvement and the new hot springs provide a facility rivalling that available to Toya Bungkah residents back in 1980. The guiding cartel at least benefits locals rather than absentee landlords.

What To Do - Specifics

I've climbed without a guide as have others. The hassles will be at the base of the climb. Once you get part way up you are unlikely to have trouble and drink sellers may offer unofficial guiding services.

You will need a flash light which can be purchased cheaply, some warm clothing and ideally rain protection.

If you are self driving/riding avoid vehicle damage by leaving your vehicle at the hotel rather than the car park at the base of the climb. One guy who suffered vehicle damage thought the cost of tyre repairs was still a bargain compared to guiding fees. Gentle persuasion will be tried first and be prepared for a forceful discussion and to resist strong demands. Some people have reported violence and though I experience fear arguing with strangers in the dark I don't think it usually gets too violent; or else I've been lucky. You might not get much immediate help in a confrontation but extreme violence seems unlikely and I've not heard of robbery. Confrontation is unpleasant and leaves a bad taste but once on the mountain a nice camaraderie develops and even the guiding fraternity seems not to hold a grudge.

Be careful looking down the 150 metres into the crater from the precipice near the bat cave (see the map) as at least one tourist fell to their death. I wouldn't want to be having an argument on this unfenced precipice.

Most of all, enjoy the experience because the view is great after it's earned and there's lots to do and see along the way.

Further Reading

1. Image galleries showing beautiful images of Batur,  beautiful images of the surrounding area, and most interestingly changes from 1967  around Batur including changes in the shape of the cone due to lava emitted from Batur's frequent eruptions.
2. Image sets showing  Gunung Batur - in the past,  a Gunung Batur climb from 2005,  Batur and Trunyan in 2009 and  Climbing Gunung Batur recently.
3. Lots of traveller reviews of Batur and surrounding areas on Trip Advisor.
4. Wikitravel guide to Kintamani.