Calling all Belt Drive Experts

Discussions related to motors other than hub motors.
This includes R/C motors, botttom bracket, roller and geared drives.
FZBob   100 W

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Idler

Post by FZBob » Dec 27 2018 1:09pm

FZBob wrote:
Dec 26 2018 2:01pm
I got the bike running with the big key in the motor shaft. Works good on the stand, but the belt is slipping at over 200 watts riding up the driveway. This time, the slipping is pretty random. The belt is tight, and the pully is centered. Hmmm. :(

Looks like it's time to try an idler pulley...
Idler.jpg
Idler.jpg (161.08 KiB) Viewed 526 times

falcongsr   10 mW

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Re: Calling all Belt Drive Experts

Post by falcongsr » Dec 29 2018 11:37am

That looks great! Assembling my 3D printer next week...

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fechter   100 GW

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Re: Calling all Belt Drive Experts

Post by fechter » Dec 29 2018 5:31pm

More belt tension will help.

You might also have some flex somewhere that allows the pulleys to move enough to lose tension.
"One test is worth a thousand opinions"

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Chalo   100 GW

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Re: Calling all Belt Drive Experts

Post by Chalo » Dec 30 2018 2:26am

fechter wrote:
Dec 29 2018 5:31pm
More belt tension will help.
And it'll hurt, too. That's sort of the problem. Belt drive has been around forever + ever, and yet hasn't made a significant mark on bicycles. It's not for lack of trying.
This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

FZBob   100 W

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Results

Post by FZBob » Dec 30 2018 6:46pm

I tested out the belt drive with the idler. It works good on the stand, but does not pass the driveway test. Much over 200 watts and it starts popping. This is more random, not once per rev like previously. The pulleys are concentric and the belt is tensioned as tight as I dare - I can see the motor shaft flexing.

At this point I needed to get the bike working again as I'm headed South for 3 months. I put the chain back on and it's working good.

Here are some observations on chain vs belt. Note - these only apply to my boundary conditions. (10:1 reduction, 7" diameter large pulley, 500 watts max at 40-80 Crank RPM, 15 mm wide). #25 chain vs HTD5 belt 15 mm wide.

Power Handling:
Chain - No problem running 200-300 watts with occasional 500 watts.
Belt - Seems to like to stay below about 200 watts. I suspect a bigger motor pulley would help.

Drag (No Load, Max RPM):
Chain - 4 to 7 watts. I don't feel the drag even though there is no motor freewheel
Belt (no tensioner) - 25 watts. This is noticeable when pedaling without the motor.
Belt (with Tensioner) - 30 watts. Noticeable...

Noise:
Chain - Some chain noise. Not bad, but not silent. The O-rings help. https://endless-sphere.com/forums/viewt ... &start=100
Belt - Pretty quiet, with a very cool high tech whir...

Robustness:
Chain - Honey Badger - It just doesn't care. Dirt - No problem. Loose - No Problem, it just slaps around and goes. Running beyond recommended power - No problem. It's not stretching much at all.
Belt - Hmmm... Seems a bit picky...

Tension:
Chain - None required - let it slap a bit...
Belt - I'm very concerned about tearing up my frame...

Sizing:
Chain - Easy to cut. Could be repaired on the trail
Belt - Might want to carry a spare belt on long rides...

Looks/Cool Factor:
Chain - Agricultural.
Belt - Futuristic. Very cool...

DHDror   1 µW

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Re: Calling all Belt Drive Experts

Post by DHDror » Apr 24 2019 6:36am

Very good thread :flame: :flame: :flame: .

One thing I learnt from my electric skateboard project is 'NOT' to use motor pullys smaller than 15T - the belt skips too often, specialy during braking (by the motor, on a skateboard).

I am building a similar project now but I opted for a 2-stage belt reduction, will post photos after the aluminum plates milling.

qwerkus   1 kW

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Re: Results

Post by qwerkus » Apr 24 2019 8:45am

FZBob wrote:
Dec 30 2018 6:46pm
Looks/Cool Factor:
Chain - Agricultural.
Belt - Futuristic. Very cool...
Uberlol ! I was considering going down the belt way too, but if think a good ol chain will always beat a belt in terms of efficiency and simplicity. My only concern would be noise, but I definitely have to try your O ring solution. Also, a larger #219 pulley should help.

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Skaiwerd   100 W

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Re: Calling all Belt Drive Experts

Post by Skaiwerd » Apr 26 2019 5:28am

It’s becoming more acceptable for quietness and maintenance free applications. Look in the sur-ron thread. One Entrepreneur is selling a belt drive sprocket conversion kit with videos showing the results. With the right engineering belts could rival chains.

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