Full suspension mountain bike Friction Drive

Discussions related to motors other than hub motors.
This includes R/C motors, botttom bracket, roller and geared drives.
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Kepler   1 GW

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Re: Full suspension mountain bike Friction Drive

Post by Kepler » Oct 17 2018 6:28pm

Hall sensors have been fitted to both front and rear brakes. The regen activates just before the brake pads come in contact with the discs and each brake lever provides 50% of the available regen. I have programmed a one second ramp to the regen so it activates nice and smoothly.

Regen amps have been increased -40A within the Vesc. This provides enough braking force to slow the bike down in a gentle manor and is all that is needed for general commuting braking needs. It will be interesting to see how the tire wear holds up with the motor now doing friction drive and friction braking.

Will get some commuting testing in tomorrow and offroad testing on the weekend. My commute is quite flat so I am hoping that the regen will be good for 10%. Offroad, I am confident that 30% to 40% is quite possible.

The regen also gives me the opportunity to go to a smaller battery and smaller battery bottle and not sacrice offroad range.

20181017_183127.jpg

I got lucky with the magnet mounting on the brake levers. The silver knob you can see on the end of the lever adjustment screw is spoke magnet for a speedo. The magnet has a 3mm thread shaft on the back. By coincidence, the brake lever adjusting screw has a 3mm threaded hole in the back. Perfect magnet mounting system for the DYI :). A lucky find.
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Re: Full suspension mountain bike Friction Drive

Post by ScooterMan101 » Oct 18 2018 7:20am

Kepler,

Instead of using sandpaper on the motor , what about making a sleeve out of Delrin that has hashtag marks around it. That should be softer on the tire .

The Derin could be machined out of a solid block, wonder what that size block of Delrin would cost ? , or be printed thin enough that it could then be wrapped around the motor and glued to the motor.

BTW for those of us that do not need stealth , what motor ( Inexpensive from H.K. or other source, not the expensive Astro's ) would provide 1.5-2 times the power than the motor that you are now using ?

Since each Full Suspension Design is different, I am thinking about a larger/more powerful motor mounted on the top front part of the swing arm, back just enough to clear the seat tube when the suspension has reached full travel. I do not mind if it would be cable actuated if needed.
My first conversion ...

https://endless-sphere.com/forums/viewt ... 1#p1077497

It's 2018 already, lets get some real , improved e-bike / e-velomobile / e-motorcycle designs .

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Kepler   1 GW

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Re: Full suspension mountain bike Friction Drive

Post by Kepler » Oct 18 2018 7:26pm

Tested all sorts of grip material. Conclusion is that it needs to be some sort of abrasive to guarantee traction in all conditions. Sleaves also increase the diameter of motor which could be problematic.

If you want a 700W to 1000W continuous motor option, use a 6374 https://flipsky.net/collections/accesso ... 90kv-3250w
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Re: Full suspension mountain bike Friction Drive

Post by Kepler » Oct 18 2018 7:41pm

27 km commute this morning using regen braking during the ride. For a fairly flat ride, managed close to 20% regen. Also I don't think my brake pads made contact with discs once. Bonus :) Much more natural to activate the regen via the brake levers.

The link below is to the mornings ride via Relive.

https://www.relive.cc/view/1913265593

Screenshot_20181019-085838.jpg
This was a quick commute spending much of my time above 35kph. Assist was not spared for this commute. The battery has 130 Whrs capacity so with the added regen, 40km rage is not out of the question.

Looking forward to testing offroad on the weekend.
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Re: Full suspension mountain bike Friction Drive

Post by FZBob » Oct 20 2018 3:34pm

Kepler,

What are you using to adhere your belt sander material to the motor? I'm considering 3M VHB tape. I have used this in industrial applications and it is extremely strong. It does have a thin foam core, and I don't know how well the foam would stand up to repeated compressions.

Also, do you cut the sanding belt straight across the motor, or on a diagonal? Worried about peeling.

Finally, do you have a preferred sanding belt, or did you just grab something? I was reading sanding belt reviews on Amazon last night, but no one mentioned bicycle friction drives :)

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Re: Full suspension mountain bike Friction Drive

Post by Kepler » Oct 21 2018 1:37am

I think that 3M tape would work but I have never tried it. I have tried lots of different methods of attaching the grip tape and nothing works better then Uglu.

In regards to belt sander material, Norton Metalite 120 grit works a treat.

When you cut the grip tape tape to length, make it 2mm longer to allow for the added diameter of the double sided tape.

I have stayed away from using grip tape for quite some time due to accelerated tire wear. Admittedly I was using much more power in the early days --- up to 1000W. However, with these low powered setups, the tire wear has been negligible which has been a pleasant surprise.
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Re: Full suspension mountain bike Friction Drive

Post by Kepler » Oct 21 2018 2:05am

Here is the bracket with the motor attached. (no snickers about the shape thanks :oops: ) All jokes asided, this bracket is about Mk5 and is refined to point that it can be removed from the bike by removing one 8mm nut and in about 10 seconds. Attachment takes a little longer, maybe 30 seconds. Note the extra diameter on the motor end of the bracket to protect the motor from ground strikes.

20181021_162648.jpg
With the speed controller mounted inside the bottle with the battery, the bike is returned to a normal bike in under 30 seconds or converted back to an ebike in under a minute. Total weight 1514 grams
20181021_162822.jpg
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Re: Full suspension mountain bike Friction Drive

Post by Kepler » Oct 21 2018 2:11am

Running out of things I can do on this bike now :)



20181020_170031.jpg


20181020_170019.jpg
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Re: Full suspension mountain bike Friction Drive

Post by urga » Oct 24 2018 2:40pm

Looks great ,John,even more stealthy than the road setup.
Are you considering rethinking your road setup now ? Using regen makes sense no matter what bike it's on. Obviously you would have to review the motor engagement system or perhaps have it permanently engaged like the mtb? Not sure roadies would like that, though, I wonder just how much drag it would actually introduce ? Then there's increased tyre wear....but a much simpler setup...fit and go...take off and go....less weight with the smaller battery + regen.....hmmm.
What other options did you look at to activate the regen? I'm still not sold on having to feather brake levers to activate it,but I totally understand why you did go that way.I'm just back from Mallorca and on some of the longer descents you would just have the regen on all the time regardless of when you do have to actually brake.I think on these situations another way of activating it might be better.
Will you be posting a video on setting up the regen for us remedial students on here? Just asking :wink:

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Re: Full suspension mountain bike Friction Drive

Post by gavinc » Nov 09 2018 12:30am

Yep, I'm now prepping the grip tape addition to my commute/road version of the Kepler drive, based on the details shared here. I wonder if I can get grip tape in red...

Hey John with regards regen on the road bike version of the Kepler drive mount, if I did adjust the end stops, say, for constant tyre contact, am I getting close enough to regen ability or do you reckon it would need a different mount here entirely?

G

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Re: Full suspension mountain bike Friction Drive

Post by Samd » Nov 13 2018 5:28am

Sub’d.


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Re: Full suspension mountain bike Friction Drive

Post by Steph » Nov 13 2018 6:45pm

Hello there,

I’ve been following discussions here for a while but stayed in my corner. I finally registered and take part...

This thread is very interesting because this is exactly what I’m aiming at. My commute is about 8km in the morning, ending with a rather steep 100m descent phase (maxing at 14%) in the morning... and reverse in the evening. What goes down needs to go back up.
I would really like that the energy that heats up my brake pads on the way to go could rather be used to speed me up home on the way back :wink:
I don’t care about kilowatts of power because I need to remain street legal, which doesn’t go very far in Europe. Also, my commute keeps me fit and I want to keep it this way :lol:

I have a rohloff IGH so hub is out of the equation, and a carbon frame so I want to keep the overall weight low. Friction with regen is the way I clearly want to go and I keep toying with different ideas to figure which is the best implementation. I’d rather take advantage of the experience of this forum to kill fake good ideas and focus on what really works...
- instead of rubbing against the outside of the wheel, what about fixing a teeth pattern on a side of the rim and drive the wheel from it? (Pro = torque transmission, no wearing, no slipping, probably better efficiency, Con = weight, cost of engineering it, tolerance to undished wheel)
- instead of a roller, use a sandpaper belt to increase area of contact (Pro = reduce slippage, reduce grinding of tire from slippage, more torque transmission, Con = possible loss of transmission efficiency due to the belt deformation)
- same with a chain, caterpillar style, to improve the efficiency. (But heavier).

Have anyone had some attempts or ideas similar to above?
I’d really like to hear your views.

Also, Kepler, since you are now with a permanently engaged friction drive: after some use, are you still comfortable with it or do you wish you could sometimes disengage it?
(I’m a bit worried to go for a design that will not give me the flexibility to disengage but the engineering of a clutch is added complexity)

Lastly, I want to give my own two cents about the initial design of this thread and the later change on the topic of sprung weight vs unstrung weight:
I think that since the friction drive has to be at the edge of the wheel, wha really matters is how far its projection on the ground is from the wheel contact point: 3oclock and 9oclock are the best, 12 and 6 the worst. Bb is very close to 3 so it’s good. Whether it’s attached to frame or moving arm doesn’t really matters.

Cheers,

Stéphane

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Kepler   1 GW

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Re: Full suspension mountain bike Friction Drive

Post by Kepler » Nov 13 2018 8:01pm

Hi Steph. Welcome to the conversation.

This type of setup sound perfect for your commute especially considering your decent is at the end of your commute heading there and at the start going back.
- instead of rubbing against the outside of the wheel, what about fixing a teeth pattern on a side of the rim and drive the wheel from it? (Pro = torque transmission, no wearing, no slipping, probably better efficiency, Con = weight, cost of engineering it, tolerance to undished wheel)
- instead of a roller, use a sandpaper belt to increase area of contact (Pro = reduce slippage, reduce grinding of tire from slippage, more torque transmission, Con = possible loss of transmission efficiency due to the belt deformation)
- same with a chain, caterpillar style, to improve the efficiency. (But heavier).

Have anyone had some attempts or ideas similar to above?
I’d really like to hear your views.
There have been some friction drives that act on the side of the tire. Never been a fan due to the additional complication and the fact that tire sidewalls are not designed for this sort of load. A tooth pattern on the rim in my opinion wouldn't be a practical solution either. Just way too much work to engineer. Grip tape and contact on top of the tire works perfectly well with the only real negative being the accelerated tire wear. That being said, my current tire is up to 1000km and at the current wear rate, still will be fine for at least another 500km.
Also, Kepler, since you are now with a permanently engaged friction drive: after some use, are you still comfortable with it or do you wish you could sometimes disengage it?
(I’m a bit worried to go for a design that will not give me the flexibility to disengage but the engineering of a clutch is added complexity)
I do sometimes wish it would fully disengage but think it is more psychological then anything else. There is a slight drag there no doubt but it is probably only a few percent. When coating down hill, I cant feel or see any difference in the speed the bike reaches. However when riding on flat ground or on an incline without assist, a few percent can be important to some people. Take a high efficiency road bike. You pay all that money for carbon fiber and lightweight components just for that few percent of rolling efficiency. I still prefer the full disengagement arrangement on my roadbike and for this reason I wouldn't convert it to a fixed drive like on this mountain bike. That being said, the drive system that I sell can be set for full time contact with grip tape if you want to utilize regen and have all weather capabilities.

Also worth noting that I have incorporated PAS into my Arduino based throttle system now. Just started road testing the system and it is looking very promising. It still uses a button throttle for boost however, for people who want it to be fully EU complaint, the boost can be removed with button then only used to turn the PAS assist on and off.

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Re: Full suspension mountain bike Friction Drive

Post by urga » Nov 14 2018 11:20am

Here's my attempt at a permanent friction drive
20181114_141709.jpg
20181114_150424.jpg
20181114_141724.jpg
:roll: I've designed it so I can disengage the motor with allen key should I run the battery flat(yet to do that,but it will surely happen). The main advantage I've found is it is mechanically silent and very smooth when running. However,and I don't know whether this is specific to me/ my motor,it does whine more than my road bike setup. Not really an issue when running,but it whines even when not even activated because it is in permanent contact with the tyre. John have you had any issues with this in your setup? Can I also ask how you managed to desolder the capacitors on your mini vesc to rotate them? I'd love to get everything even more compact in the bottle setup.
I am looking for another button throttle and programmed Arduino for the bikes.I'm happy to buy this from you if you are still selling,but I'm also willing to give it a go myself if it isn't to steep a learning curve to program the Arduino?
As an aside,is there any way that regen could be implemented with the Kepler Drive system ? Could it be activated above a certain rpm/speed via the vesc after the motor is activated as normal on a downhill section?

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Kepler   1 GW

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Re: Full suspension mountain bike Friction Drive

Post by Kepler » Nov 14 2018 7:53pm

That is a really neat implementation. Nicely done.

I think the whine you are talking about is coming from the tread on that tire. If you have a tire with a slick center, it would be worth trying that and see how that goes. The other thing is that I have found variations in the noise that the Flipsky motors make. You might just have a noisy one. A bearing change to some high quality bearings may help. Tweaking the FOC values may help also.

With the Arduino, and button, yes I can still supply these if you like. I cant think of anyway to have the Vesc activate regen based on speed or RPM. Perhaps a 2 button arrangement might suit you. One button for throttle and the other button for regen.

With regards to programming Arduino's, personally I found it quite challenging. I had zero programming experience and with Arduino programming language being a modified version of C++, I really didn't want to spend the time required to become proficient enough for the projects I had in mind. However, using Visuino to block program made all the difference. Still a good learning curve but it didn't take me too long to be constructing the logic I was after. I now really enjoy the programming side and although it not actual programming, it is still a process of linking logic together to create the desired result.

Give it a go. Buy an Arduino Uno starter kit, grab a copy of Arduino and Visuino software and start experimenting.
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Re: Full suspension mountain bike Friction Drive

Post by urga » Nov 15 2018 2:54pm

Oh Dear,I do believe I'm going to give it a go!.
I fear I'll soon be making more of a whine than the Flipsky motor.
I had a look at the micro(because of the usb)rather than the mini. Any drawbacks to this(apart from a i/o deficiency)? Was it the 3.3v version?
Last time I programmed it was in the 80's and it was Fortran! I'm Googling Visuino...................

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Kepler   1 GW

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Re: Full suspension mountain bike Friction Drive

Post by Kepler » Nov 15 2018 7:08pm

Very good. The programming side becomes a hobby within a hobby.

I would go with with a Nano. Nice and compact and has a built in TTL so direct USB connection. You don't have to worry about 3.3V or 5V if you are using a Nano. They handle 5V regulated which is what the Vesc supplies. IO count is basically the same for most models.
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Re: Full suspension mountain bike Friction Drive

Post by Kepler » Nov 18 2018 7:17pm

I have been using this bike for both off road and commuting duties of late and as such have been racking up some distance.

I am finding that this bike is only marginally slower over the commute compared to my assisted road bike but far more comfortable and the bike can be used in all weather.

Tire wear has been better then expected. I have clocked up just over 1000km and still have quite a bit of life left in the tire as indicated by the two groves on the top. I would say I am 60% to 70% through this tire so 1500km plus isn't out of the question.

All in all, not a bad result.
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Re: Full suspension mountain bike Friction Drive

Post by falcongsr » Nov 19 2018 6:00pm

How often do you have to replace the friction material on the outside of the motor?

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Re: Full suspension mountain bike Friction Drive

Post by Kepler » Nov 19 2018 6:27pm

I have replaced it once within the life of this tire and that was just recently. The friction material lasts fine however I did quite a bit of wet weather operation over the past few weeks. The constant saturation will shorten the life of the friction material. Predominantly dry weather operation I think the friction material will outlast the tire.
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