Are belt drives ok off road and in the mud?

[John in CR]

Now that I have some compact high power motors that are easy to put in a mid drive I want to try a belt drive so I don't spoil the silence with a noisy chain. This bike will be for off road riding, so I'm wondering if belt drives have a problem in mud and sand. Anyone using a belt drive in harsh conditions? Are there special precautions that work to keep the muck out if it is an issue, or do I need to come up with a lantern type of open sprocket?

John

 

[grindz145]

Hey John. This is a classic problem for belt drives. What happens is that rocks can get stuck in them, and eventually embedded in the belt, which will cause them to rip or eat up the sprockets. It's a well known problem and I don't know of any good solutions.

I noticed that a while back when all the smaller BMW motorcycles started using belts, with the exception of the GS models, which all used chains.

 

[HumboldtRc]

On a Quantya, wih a primary belt drive, in one or two laps around the track when, it was nice and loamy but not muddy, I had the belt packed up with so much dirt and rocks the bike actually came to a stop because the belt could not turn anymore. The mud was about a quarter inch thick on the pully making the belt stretch, and locking up the drivetrain. I would never use a belt drive if it is going to be ridin off-road, and on loamy tracks. I then took out the another Quantya that had the chain primary drive, and had no issues with the loam on the same track and same conditions.

 

[John in CR]

Damn, thanks guys. I'm really glad I asked, because offroad use where getting the weight out of the wheel and motor up and away from the muck, and simply being able to use a large wheel are big pluses, were my primary reasons to go mid-drive. Well, there's being able to go to high voltage and gear down for extreme power too, but now that I have some truly silent motors (not even a hint of that startup growl), giving up the silence is a fairly substantial detriment.

Oh well, chain it is then. At least everything is readily available with plenty of variety and low prices, even down here in the land of what you need is hard to find.

If quiet is your goal, and you need less than a 2:1 reduction with max input expected to be 1800rpm or less, any recommendations on the drive sprocket tooth count?

John

 

[REdiculous]

1800rpm is pretty slow, so any 'sane' combo should be fine I think...22/44?...I dunno....I'd use whatever looks good.

 

[grindz145]

An enclosed belt drive would be really cool....

Otherwise, a venerable chain will have to suffice. I've been looking for belt drive stuff for my magnum build, but it hasn't been wroth the effort so far.

 

[mdd0127]

An enclosed belt drive would be really cool....

:wink:

Enclosed is the way to go with belts.

 

[ohzee]

I think you are on to something. I think there is a big market for a high power mid drive that wont break the bank
and is not overly complicated.

Tonight I am removing the mid drive kit I have on my yuba. I have went thru 2 mac motors and with my skill set &
tools available nothing short of a dd motor which can take 100+V and not melt will make me happy.

So back to a hub motor for me.

I like the fact you keep pushing the ceiling keep it up man.

 

[MitchJi]

Hi John,

Damn, thanks guys. I'm really glad I asked, because offroad use where getting the weight out of the wheel and motor up and away from the muck, and simply being able to use a large wheel are big pluses, were my primary reasons to go mid-drive. Well, there's being able to go to high voltage and gear down for extreme power too, but now that I have some truly silent motors (not even a hint of that startup growl), giving up the silence is a fairly substantial detriment.

If the belt will drive the cranks maybe you can set it up so that dirt in the belt/pulley's won't be an issue?

If quiet is your goal, and you need less than a 2:1 reduction with max input expected to be 1800rpm or less, any recommendations on the drive sprocket tooth count?

But with a 1800 max rpm (pretty low compared to high rpm rc primary chain drives) with only a 2:1 reduction it should be pretty easy for you to build a pretty quiet system.

Larger drive sprockets are better but anything 14t or over should be fine. More info on sprocket sizes/noise here:
http://chain-guide.com/basics/2-2-1-chordal-action.html

You will find that the position in which the chain and the sprockets engage fluctuates, and the chain vibrates along with this fluctuation. Even with the same chain, if you increase the number of teeth in the sprockets (change to larger diameter), vibration will be reduced. Decrease the number of teeth in the sprockets and vibration will increase.

Even more information (searching mile's posts for chordal):
http://endless-sphere.com/forums/se...posts&sk=t&sd=d&st=0&ch=300&t=0&submit=Search