FS: Commuter Booster Friction Drive Beta Units

[adrian_sm]

Foreword: This first post maybe tweaked over time, to keep any updates in one spot, or fix any errors.

For sale is the next 'Beta' batch of my Commuter Booster drive units.

This is a light weight friction drive ebike system.
See the website for more details. http://sites.google.com/site/commuterbooster/
Or the development thread on ES here. viewtopic.php?f=28&t=22187

Price is AU$170 + shipping.
Shipping was in the AU$20-25 range last time, so should be similar but I will update this post when I get real quotes. Let me know if you would prefer registered post, or cheapest option. My preference would be registered just in case.

Note: This is for the mechanical components only. You will still need to provide you own battery, motor, ESC, and throttle solution.
[EDIT: 2011-12-17] Here is a link to the complete shopping list.


I can provide the motor and ESC if you wish, but will charge a mark up to cover my cost of ordering from HobbyKing or Leader Hobby, assembling the drives, setting up the ESC, extra shipping costs etc.

DSC_2307.JPG (135.08 KiB) Viewed 5131 times

The design is only slightly different from the Alpha units, the key differences being:
a) a press fit for the main pivot shaft into the swing arm (an Alpha tester wanting upgraded parts let me know)
b) removed face exit phase wire slot (not shown in photo)
c) added mounting holes for 44PCD & 30PCD mounting holes to suit most 63 & 50mm motors (not shown in photo)
d) added a hole for securing phase wires to swing arm
e) fully assembled, minus the motor

Here is what a complete system looks like on the bike. This whole bike weighs in at ~14.5kg total, including the drive unit, motor, ESC, BrainBox interface and a 5s20Ah battery pack. This can peak over 2000w, but I typically run it at 500-1000w power limits.

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To place an order send an email to commuterbooster@gmail.com (or a PM but I prefer an email). With the following details.
- Seat tube diameter (check the installation template to ensure it will fit your bike)
[EDIT: 2011-12-17] I still have some smaller swing arms suitable for 50mm motors. So if you are happy with lower ~500w power limits, this may be for you.
- Quantity required for each seat tube size
- Name
- Address
- Any special instructions

I have just placed orders with my suppliers for the updated parts, so these are not likely to ship prior to Xmas. Sorry, I'll try my best.

I also have my Brain Box for sale in a seperate thread. The Brain Box is my custom design ebike computer/throttle interface/data logger specifically tuned for the Commuter Booster friction drive. I highly recommend it as it makes the whole Commuter Booster a refined and integrated package, and is the whole reason I delayed releasing the Beta units so I could sell people both. I'll leave the details for the other thread.

I'll be updating the Commuter Booster website soon to reflect all the latest developements.
Also check out the videos on the Commuter Booster Youtube stream which shows all the steps off putting a complete system together.

Here is the one showing the assembly of a motor, onto the Commuter Booster unit.



- Adrian

[adrian_sm]

Reserved

[adrian_sm]

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[adrian_sm]

Hi everyone. I have had quite a few emails to get through from a great response. So please be patient as I get through to yours.

I'll post answers to any questions I recieve that I think others will be interested in soon.

Thanks for your patience.

Adrian

[adrian_sm]

Answers to some frequently asked questions:

how do those friction drives handle water & mud ?
Do you totally have to stay out of any type of water with them ?

The friction drives are really suited to on road use, and don't like rain as it reduces the maximum torque the drive can transfer. It is possible to adjust the engagement to compensate but there is a limit. With grip tape on the motor can they can handle light rain. But they are definitely not the drive you want for off road muddy rides. Then you should stick with a more conventional ebike drive.

What comes in the kit?

This is just the mechanical mounting unit for the motor. It does not come with motor, ESC, battery etc.
It does come with:
- 4 high quality screws to fasten the motor to the swing arm
- a releasable cable tie to secure phase wires to the swing arm
- some 80 grit grip tape suitable for a 63mm motor (can be cut down to size for other motors)

What will I need to assemble the drive?

- screw driver and allen keys
- contact adhesive if you decide to use grip tape on the motor to improve traction in wet/dusty conditions, at the expensive of increase tire wear

How quickly does it wear the tire out?

This depends on a lot of things:
- whether you use grip tape on the motor or not
- power level, or more accurately the torque the drive is transfering
- type of tire used
- drive alignment
- drive maximum engagement
- tire pressure

When the drive is run without grip tape it has minimal impact on tire wear.

If grip tape is used, more care needs to be take in tuning the drive engagement and maximum power to control tire wear. But when correctly assembled at moderate power levels ~500w, it will wear out tires about 2-3 times as fast as normal.

What type of tire should I use?

Not knobblies. Something with a smooth centre tread.
A relatively flat centre section of the tire also minimises tire wear when grip tape is used on the motor.

How noisy is the drive?

Noisier than a hub motor.
The noise level is higher the higher the torque being transfered, so for a constant power level will be louder at lower speeds.
I find it acceptable at 500w power levels, but become more aware of the noise when running higher power levels up around 1000w and above.

Can I install the Commuter Booster on a folder?

Not sure. The Bromptons are not suitable due to a different rear triangle without a seat tube in the required location. Others have installed a Commuter Booster style drive on a Dahon. Best bet would be to try the installation template to get an idea of wear the main pivot block will clamp on the seat tube, and make sure it fits.

I have cables running down my seat tube. Will the drive fit?

Not currently. If you provide details of there exact location of the cables, I may be able to modify the main clamp/pivot block for you to suit. Please contact me and I'll see if I can do it.

How do I pay?

I'll post details closer to when I am ready to ship.

[cwah]

Hello Adrian,

Got few additional questions:
- Does the motor/kit is water/dirt resistant? I understand if it won't work as good when it's raining. But would that be bad for the motor? I mean shall we protect the motor from water and dust?
- I have an ebike reaching 33km/h at 500W and usign 12wh/km. But this is a heavy mountain bike (25kg). For the same configuration what should I expect from the commuter booster? If I have a dahon speed, would I still have 43km/h at 500W? (as for your road bike?)
- Is it possible to reach 50 km/h? And would that be good for the motor?

Thanks a lot.

[neptronix]

ooh.. if you had a long front fork ( like a suspension corrected solid fork ), or reduced your front wheel diameter a tad, this could make for an extra additional 1000w on a rear hub setup..

This is a cool unit. Thank you for bringing this to market

[adrian_sm]

- Does the motor/kit is water/dirt resistant? I understand if it won't work as good when it's raining. But would that be bad for the motor? I mean shall we protect the motor from water and dust?

The motor will survive as long as you ensure all the wiring connections are protected from the elements. The coils are all coated, the magents don't care, the bearings would be the first thing to go. Most of the motors only have sheilded bearing, so if you were to do it I would replace the bearings with equivalent sealed versions. But seriously if you plan on riding in the rain all the time, don't buy this, go for a hub motor.

- I have an ebike reaching 33km/h at 500W and using 12wh/km. But this is a heavy mountain bike (25kg). For the same configuration what should I expect from the commuter booster? If I have a dahon speed, would I still have 43km/h at 500W? (as for your road bike?)

40ish kph is with me pedalling. 12 wh/km is more typical of cruising at 40kph, averaging maybe 27kph over a whole trip, using the drive all the time. It is just a couple of button clicks to adjust the power limits on the bike. So it is easy to tweak. Main thing is to make sure the kv of your motor will give you a no load speed above you max assist speed you would like, but not much more.

- Is it possible to reach 50 km/h? And would that be good for the motor?

Yep. 50 kph is definitely possible with the Commuter Booster, but IMHO is pushing the limits of what you should do on a bike, and in most parts of the world would be outside what is permissable for an ebike, so it will all be on your own shoulders liability wise. The 6374-200kv motor on 6s battery would be pretty close to giving you 50kph, I would need to check. I was running that set up a while ago, but don't like that sort of cruise speed on a rigid road bike, it is too harsh. 40kph on the flat is more my style.

- Adrian

[NeezyDeezy]

I'm pretty sure your fork is installed backwards in the bike in your photo.

[adrian_sm]

Hmm. I am pretty sure it is the right way around, assuming you are talking about my road bike in the first post.

[cwah]

Thanks Adrian. Still looking for the right bike to purchase for the commuter booster and after I should come back to you

[heathyoung]

I'm pretty sure your fork is installed backwards in the bike in your photo.

Well, the brake bosses are on the front, but agreed its a pretty funky looking fork

[adrian_sm]

I have just reviewed and updated the shopping list, so you can see the full cost of all the parts required to put a Commuter Booster kit together on your bike. These are just recommendations for parts, if you know what you are doing or already have some equivalent parts you can use them instead.

Shopping List

- Adrian

[adrian_sm]

I still have some of the smaller swing arms suited to 50mm motors in stock.

So if your bike doesn't quite have enough room for the recommended 63mm motors, and you would be happy with a low power setup 200-500w, this may be for you.

Price is the same. It looks like this:


- Adrian

[adrian_sm]

Update: Corrected shopping list. Had a double listing for connectors, instead of the Motor.

https://sites.google.com/site/commuterbooster/shopping-list

[cwah]

Hello,

I'm thinking of buying a new Dahon Uno and add the commuter booster to it:


Seat tube size is 34 x 580 mm (forged aluminium clamp). full specs here: http://www.evanscycles.com/products/dah ... 9#features

Do you think it could work?

[adrian_sm]

Do you think it could work?

Yes. But..

Check out this thread. viewtopic.php?f=28&t=31457&hilit=folding

It is definitely possible, but you are very limited in the where you can place the drive on the seat tube. This limits the adjustments you can make. Normally you adjust the angle at which the motor contacts the tire by sliding the drive unit and down the seat tube. But you can't really do this with the Dahon. So I think ferias77 adjusted the length of the swing arm instead. Essentially changing the distance between the swing arm pivot point and the motor mount. If ferias77 could confirm the geometry I may be able to modify a Commuter Booster to the same specs. The important things are:
- seat tube diameter
- distance between pivot axle and seat tube
- distance between centre of pivot axle and centre of motor axle
- motor diameter
- angle between main pivot/clamp block and swing arm at initial motor contact with the tire

If you are lucky the geometry will be the same as the Commuter Booster, but I can't be sure unless we check. Sorry for the extra effort required but the drive unit is not really designed for this type of bike at the moment. You may be better off going for one of Keplers eBoost units if mine can't be adapted.

- Adrian

[cwah]

Ok thanks Adrian.

I'm not a very technical guy, I'm going to ask Kepler.

But I'm not sure if it's working either (and it seems to be out of stock).


By the way, I'm just looking for a folding bike I can carry on the public transport (bus and tube). So if you have anything working in mind I would be interested.

ps: I'm still wondering if I should buy this bike. If I buy this dahon uno and I get a ruler. I should be able to measure the distance and angles. Would that be enough for you?

[adrian_sm]

From a number of emails I have received.

How can I use a normal twist/thumb/analog throttle with the commuter booster?

The brain box is currently optimised for use with the digital button throttle. In the future I will be modifying it for use with analog throttles, but not yet. Sorry.

If you are keen on a twist throttle the options instead of the Brain Box are:
(1) Buy a RC Cycle Analyst from ebikes.ca
- here is the ES thread
- here is where to buy them from

(2) Roll your own
- modify a servo tester to accept a hall throttle, and output the correct signal for the ESC. Here are the instructions
- I would also recommend using a one of these to adjust the ramp up rate. This helps smooth drive engagement/disengagement.
- this is a very basic and cheap setup, so it will not enforce any minimum speeds, or limit maximum power. So beware!

Cheers,
Adrian

[crusoe]

Do you have any videos with you actually riding with the booster?

[adrian_sm]

Hey,

I really need to spend some time and get some better videos, but here is one from on-board during a recent group ride. It gives you an idea of the sort of speed and sound to expect when I do accelerate off. This was with the drive restricted to ~700w.



And here is an older one, with the drive on a mountain bike. The camera setup was very average so it is pretty shaky, and all the drive noises are amplified, but at least it shows you how the drive engages.

[adrian_sm]

Update:

Hi everyone. The holiday season is over for me and my suppliers now, so I'll be finishing of the drive units soon and contacting everyone to confirm the order, arrange payment, and ship things out.

Thanks for your support and patience.

Regards,
Adrian

[adrian_sm]

Update:

Thanks for everyone's patience. The holidays didn't leave any much time to make kits, and I have had to convert my garage into an office workshop to give me the space this little project needs. Unfortunately this means I won't have the workshop functional for a few more days yet. The good news is that I have the CBs 90% made, enough parts for the Brain Box's, and my family is interstate for a week more so no distractions.

Again sorry for the delay, but I really need to make a dedicated space to work on the Commuter Booster to make production more efficient. I hope you all understand.

Regards,
Adrian

[adrian_sm]

System Design:

I have had a few people asking component select questions, so thought I would post the basics here.

Volts & KV, and assist speeds
You need to select a battery voltage, motor diameter & motor KV to give you no load speed slightly in excess of you required maximum assist speed.
For example I recommend a 5-6s Lipo (20-24v) 63mm motor with 200kv. This gives a no load speed on 20v of 47.5kph, and 57kph on 24v. This means I still have a level of assist up to these speeds, and keeps the motor and ESC happy. Running at a higher voltage would require more expensive ESCs, that would just end up having to PWM the phase current more to keep power levels down at the same level, putting the ESC under more stress. Picking a motor with a higher KV will give less torque, and have the motor running at lower efficiency for the normal operating speeds, resulting in more waste heat and lower sustainable power levels.

A quick equation for the no load speed is:
kph = battery volts * motor diam in mm * motor KV / 5305
mph = battery volts * motor diam in mm * motor KV / 8538 [Edit: corrected]

Note: The no load speed is where the motor provides no work, so for the real assist speed drop this number down a bit, and calculate it at the depleted battery voltage.

Battery Selection
I recommend 5s or 6s LiPo batteries. These are cheap, energy dense, easy to parallel up, easy to balance with an RC charger, and don't require the high voltage RC ESCs. You could also pick 4s, but these will require high KV motor to compensate, and require high battery currents for the same power.

Motor Selection
Apart from picking the right diameter and KV as mentioned above, getting the heaviest motor will allow it to handle more power. As it has physically more mass to absorb the heat and larger surface area to dissipate it to the air.
A motor with a skirt bearing will resolve the tire contact forces better, and give longer life.
A small diameter motor (ie. 50mm) will fit smaller frames, but will not be able to deliver as much power.

If you are happy with ~500w power levels you could probably get away with a 50mm diameter motor. But I will usually recommend the 63mm motors

Power Limiting
A normal RC ESC and motor combination does nothing to limit power levels. This results in lots of power but is also likely to overheat, loss sync, wear tires due to higher forces. That is why I recommend either using my Brain Box, or the Cycle Analyst -LRC. These have closed loop controller of power/current and enforce a minimum speed to maintain the health of the system, amongst other advanced features. Some people (most notably Lyen) have been experimenting with the sensorless ebike controllers so these may also be an option soon.


So please feel free to roll you own system design and electronics, but also be aware of the limitations of friction drives, RC motors and ESCs when doing so.

- Adrian

[adrian_sm]

Oh and here is a picture of a bike I pulled off a rubbish pile and turned into a single speed test mule. Just cost me $120 for new wheels, tires and chain. Plus a spare saddle I had. The ride is a bit harsh compared to a modern road bike, but I still like it. As pictured it weighs about 15kg, does 50kph.