Full suspension mountain bike Friction Drive

[frenchie]

Very cool!
I can't quite work out what is holding the motor to the frame....is it really held on with four cable ties?

 

[Kepler]

The motor is attached to swingarm as it needs to move with the suspension. Yes 4 cable ties are used to attach the drive. Double sided tape is used between the motor bracket and the swingarm then 4 good quality cable ties are used to hold it in place from there. Keep in mind this an oddly shaped carbon fibre swingarm so care needed to be taken not to damage or crush the carbon fibre when attaching the motor bracket.

I thought this would be an issue but the mounting system is surprisingly robust. I ride this bike hard through jumps and knarly rock gardens. It have never come loose and I have never had one of the cable ties fail on me.

 

[frenchie]

Superb! Thanks for the info
What app are you using on your phone? Did you need to add bluetooth to your VESC or are they built in?
I've just ordered a 6384 motor and a FSESC4.20 from Aliexpress for less than €73 delivered!
So I'll try and attach them to my 'plastic' Orbea road bike, hopefully next month
But if it works out I'm tempted to look for a secondhand mountain bike too.....The EX took my old dual suss like most other things when I got booted out the house
this is the controller, hope it works...

 

[bose]

Kepler, have you looked into using a mouldable plastic for using as a support against your frame? I.e. plastic pellets that becomes clay like in 60degC (might be an issue in Oz?) and could then be pushed around the part of the swingarm you want to use as attachment point for your drive. Then attach the drive with zip ties and you should have a stable mount that is easy to move between bikes - just mould a new “bracket” and off you go.

The frame should of course be protected with cling film or the alike, and the plastic should only be moulded to the underside of the attachment point - acting as a support plate with perfect shape to your specific frame or swing arm. It is then easily removed as well.

 

[jangles]

You guys amaze me . Altho I have no idea what most of this stuff is I applaud you . Smartest damn bunch of people I have been around !!!!

 

[Kepler]

Superb! Thanks for the info
What app are you using on your phone? Did you need to add bluetooth to your VESC or are they built in?
I've just ordered a 6384 motor and a FSESC4.20 from Aliexpress for less than €73 delivered!
So I'll try and attach them to my 'plastic' Orbea road bike, hopefully next month
But if it works out I'm tempted to look for a secondhand mountain bike too.....The EX took my old dual suss like most other things when I got booted out the house
this is the controller, hope it works...
fesc2.png

A 6384 motor is quite wide and may not fit between your cranks. I normally use 6354 motors but I know a 6364 will fit Ok also.

The Vesc Mini are great. That's all I use these days.

 

[frenchie]

You guys amaze me . Altho I have no idea what most of this stuff is I applaud you . Smartest damn bunch of people I have been around !!!!

what amazes me is how cheap all this stuff is!! god bless the little chinamen and women
if it doesn't quite work out you can always flog the bits online
I love technology and I think sometimes you just have to 'have a go'

 

[frenchie]

A 6384 motor is quite wide and may not fit between your cranks. I normally use 6354 motors but I know a 6364 will fit Ok also.

The Vesc Mini are great. That's all I use these days.

ah yes, rule number 2, never believe what a chinaman says.....
I looked at the dimensions and a seller picture showed overall length at 80mm BUT that's the body excluding the shaft
I've got a problem with the Orbea, the rear gear cable is external under the frame
What do you think about mounting a motor in the space 'under the seat'?
I would need a 50mm diameter motor for the Orbea so probably not doable....
BUT a 63mm might just squeeze in the space under a Scultura....it has a flat tyre at the moment....
no flats in 2 years then you get 2 in 2 weeks :lol:

Orbea...

 

[Kepler]

Looks a little tight in there but it has been a well proven mounting position. Check this out.

https://endless-sphere.com/forums/viewtopic.php?f=28&t=22187



Friction drives using RC Outrunners have been around for a long time. What made them cooler was the Vesc and FOC mode which shut them up and gave us true current limiting in a tiny package.

 

[frenchie]

Looks a little tight in there but it has been a well proven mounting position. Check this out.

Friction drives using RC Outrunners have been around for a long time. What made them cooler was the Vesc and FOC mode which shut them up and gave us true current limiting in a tiny package.

Excellent thanks again Kepler
You mentioned an arduino, what is that used for?
And what does your favourite 'accelerator switch' look like?
Happy riding!

 

[92se-r]

How are you guys attaching the custom rollers on the motor case?

 

[ahagge]

Hopefully not too dumb or OT question for someone who might know...

Can the FlipSky Mini FSESC 4.20 (which is labelled for 3-13S LiPo) be used with Li-Ion batteries - the ones built from 18650 cells that are often sold for e-bikes? I've been playing with a build using a lesser ESC and a 6S LiPo battery, but I'm really scared of the volatility of LiPo. My motor is rated for up to 10S, so I'd like to go with a 10S3P 18650-based pack.

If you know the answer - thanks in advance for sharing!

 

[urga]

Yes......and do not fear

 

[Kepler]

A quick update on the Stumpjumper conversion.

Firstly a couple of upgrades to the bike. New rear shock. Fox DPX2 replacing the stock unit. Also replaced the stock Sram NX derailleur with the new ASX12 speed electronic derailleur.

[youtube]j0FVsFWmcZA[/youtube]

Such a nice shifter with the added bonus of freeing up an internal cable routing path. This routing path is now used for the drive activation button cable.

Machined up a new roller. This time I have gone for mild steel with an aggressive knurl. I was concerned that adding a substantial metal ring around the motor might upset the motors magnetic field however turned out not to be an issue.



I have now motorized the activation of the drive to the tire. This is done using a high torque 25kg pull RC servo driving a custom cam and cable to the drive swing arm. The cam goes slightly over centre at the end of its travel so the servo is not under load once the drive is activated. A separate UBEC was added to the Vesc to drive the servo as the 5V supply from the Vesc was inadequate for the high torque servo. An Arduino was then programmed to drive both the Vesc and servo through their correct range.

[youtube]C859pWVvlwQ[/youtube]

Grip from the knurled roller to the tire is superb with no slippage at 200W and in the wet. 200W assist is perfect for this bike. Certainly not a free ride and just enough to give you a meaningful hand up the hills which makes those riding sessions extra enjoyable.

Total drive system has added 2kg to the bike. With the drive disengaged, the bike feels the same as it was before the assist was added.

 

[Manbeer]

Damn, stop making all this cool stuff you wont sell us peasants! :lol:

 

[chilau2000]

Kepler inspired ebike conversion for my son's bike.
Running a VESC, 6354 motor on 6S, limited to 20mph.

Has a kill switch and thumb throttle

 

[TNC]

Wow!...lots of wizardry present in this thread. I'm a total greenhorn on the ebike venue, only recently exposed to them in the form of Trek and Specialized emtb models and my recently built BBSHD into my '08 Santa Cruz Nomad. I am not a greenhorn on bike mechanics, suspension technology, and decently gnarly off roading.

I had never heard of friction drive as a thing. Reading through this thread it's apparent how much mechanical tech and electrical expertise is at play here. The only thing I see as a limiting factor is the kind of tire you're going to have to run to make it work. Honest-to-gosh mountain biking in technical terrain usually requires some decent tires to keep from busting your keister...unless you're riding on something like the sandpaper on the Slickrock Bike Trail at Moab. Do not take my assessment as a slam on the impressive effort and results in this thread, but on a lot of the looser terrain one often encounters at many of the true off road trails for mountain bikes, fairly aggressive knobby patterns are almost a requirement. It does not mean you can't get a mountain bike through those trails with the type of tires required for friction drive, it just seems it's a big handicap.

I also wonder how this type of drive performs with the sticks, grass, weeds, rocks, and other trail debris often encountered in true off road conditions that gets kicked up. That drive unit looks awfully vulnerable to such things. Regardless, I am highly impressed with some of the work present in this thread. It's always good to learn something new...and I did.

 

[gianfr80]

hi i made a nice setup that work awsome on a straight road, can reach up to 50km/hrs, also on hills no more than 15% can reach up to 33km/hr with pedal help. the problem its on high angle hills, there is no way for it to work, i have to change shifts on the bike an end up peddaling all the way up with almost no help of the motor an really slow.

have a:
Flipsky FSESC Mini V4 rated 50A
TURNIGY AERODRIVE SK3 - 6374-192KV MOTOR OUTRUNNER rated 80A
An a hailong 48v 12.8ah with BMS rated as 30A continuos discharge. made of lg mh1 3200mah, 13s4p

an running on FOC mode
set 80a on motor
an 30a on battery

any idea what could a change to improve the uphill performance?
(its ugly as hell , but it works )
[youtube]https://www.youtube.com/watch?v=381T4H5lJiI[/youtube]