FS: Commuter Booster Friction Drive Beta Units

[full-throttle]

bullhorns - check
coloured tyres - check
coloured chain - check

all you missing is a card in the spokes, a Knog Frog flasher and some skinny jeans

[adrian_sm]

I'll pick them up next time I am in Fitzroy.

I rode this bike in to the Sustainability thing on at Birrarungma the other day. Single speed and electric assist was a nice combo. But I had it on 6s, and I can't keep the cadence up at 50kph. What gearing do you run on the BPM hardtail?

[full-throttle]

I rode this bike in to the Sustainability thing on at Birrarungma the other day.

Hence the green combo

When I was using BPM code-9 (55kph top speed) the ratio was 52/16 and I was still topping out.

With code-12 (40kph) and 48/16 it's just right.

My singlespeed roadbike is 44/15 - comfy at 25-35kph, top out at around 48kph.

[adrian_sm]

Mine is 52/16. Maybe this will teach me to spin.
But I think I will run it on 5s in the future.

[cwah]

Hello Adrian,

Got another bike (Pacific If Reach) I was wondering if it may fit:


Asked Kepler but his config wouldn't work directly. Any chance it may work with your friction drive?

[adrian_sm]

That would be a custom design which I unfortunately don't have time for.

Sorry.

- Adrian

[cwah]

Ok thanks Adrian

[deepfraught]

Great video of the Melbourne e-bikes ride.
Looking forward to the new units, I think I'm believing the 40kph top speed is the sweet spot.
The 2nd speed option to get "Give it all you've got Scotty" power sounds nice for those power hungry speed times.
I did a battery range test on hub motor at full steam and found 50kph+ blustery wind in ears, tiring noise and concentration for shared path traffic/obstacles.

[adrian_sm]

Quick pic of the next batch of CB's ready to ship.

fr_965_size640.jpg (159.12 KiB) Viewed 1083 times

[adrian_sm]

New manuals are currently being uploaded to the website. Sorry about the huge file sizes, I couldn't be bothered working out how to compress them. The manuals are still not perfect, but should be good enough for most of you.

- Adrian

[deepfraught]

Received beta unit and Brain Box today, thanks Adrian
Adding feedback to your development thread.

[adrian_sm]

Glad to hear it arrived safely. Looking forward to hearing your impressions.

- Adrian

P.S. I hope I sent you the correct size, unlike one unit I had to resend to Singapore.

[adrian_sm]

Oh, and for all the beta testers. I erred on the conservative side for the dead stop controlling how much the motor can swing towards the seat tube. If this is restricting your installation it can be modified.

Cheers, Adrian

[adrian_sm]

Cheap Motor

Leader Hobby have the 6364-230kv motor for cheap at the moment. I haven't tried this motor specifically, but have been very happy with the 6374-200kv bigger brother.

Anyway US$33 is a pretty darn good price. I just bought five to build up some demo units. So if you have bought a kit recently and have yet to get a motor, this could be a good choice.
http://www.leaderhobby.com/product.asp?ID=9394001224158

[kevo]

Adrian,
Any idea why they are offered so cheap? What does the Turnigy SK3 have that these don't.
Less than half the price is significant, thanks for pointing out this source.

[deepfraught]

They also had the 6374 for sale shy of 40, so bought a pair each for me and a friend. Thud has the simplified RC reduction in progress using a 6374 as well, so figure spare or other platform to try.

[adrian_sm]

Adrian,
Any idea why they are offered so cheap? What does the Turnigy SK3 have that these don't.
Less than half the price is significant, thanks for pointing out this source.

Quality. The SK3s seem to have nicer finish, claim to have better bearings, they also have an internal fan.

I really need to set up some sort of dyno, so I can get better relative data on these motors. Trying to compare them from road data has not proved consistent enough to pick the best motors for my application.

Maybe a real simple water brake, a tacho, volt/current/temp sensors setup would be enough.... hmmmm..

[adrian_sm]

They also had the 6374 for sale shy of 40, so bought a pair each for me and a friend. Thud has the simplified RC reduction in progress using a 6374 as well, so figure spare or other platform to try.

Really??? When I looked at the 6374-200kv motors they were up around $90.

Unless you are talking about these ones. Not as ideal for the friction drives as they don't have the skirt bearing, but a bargain for Thud's reduction unit.

[deepfraught]

Doh! That's exactly what I did. I've emailed to ask if they can swap the product codes and amend the invoice, only put in last night and order as only payment received so hopefully they're obliging. Else I'm going to become Thud's best pre-order customer =P

[adrian_sm]

I have run motors without skirt bearings for 500+ kms and they are still fine. So don't stress too much.

[deepfraught]

OK thanks, just trying to get my head around it, what do they have instead of a bearing at the skirt then, a bushing?

[adrian_sm]

Nope. Nothing.

The axle has bearing at each end of the stator, so it is well supported.
The end ?bell? is then attached to the end of the axle via a closely tolerenced hole maybe 15mm deep.
Then the outer shell is secured to the end ?bell?. This is usually just a press fit, but some motor glue, of screw it on.

So the weak point is probably how the shell attaches to the bell, as the tire force will create a cyclic moment that will try to wiggle the shell off of the bell.

But it hasn't been an issue for me yet. But I think I remember someone once having it come loose.

Motors with a skirt bearing will support the end of the shell, so there is hopefully less of a cyclic moment trying to work the shell off of the bell.

Here is a random pic that may help.

[deepfraught]

Thanks, they quickly replied and said the order hasn't been printed yet so no problem changing and will refund the difference to my paypal.
I was considering using existing a 6S 5Ah battery with up to another two to swap over for longer distance rides (trio currently in an 18S pack). Now with higher kV but smaller motor will have to check the kV/battery/unloaded wheel speed table from another thread to see if that's going to be way too high, and get new batteries for better voltage/kV match.

[adrian_sm]

The 5065-270kv work well, but won't take as much power as the 63mm motors. But they sure do make for a great compact/lightweight setup. just don't expect to climb mountains with it.

[adrian_sm]

@deepfraught. Oh and just get your kit running, your mate keeps hassling me. I keep telling him to try out yours first to make sure it is what he wants. Try before you buy and all that.