Belt drive update. I've broken a belt.

I’ve been commuting off road for over a month through all that rain without any problems, but 100km at SITS ended up breaking the belt.
For those who weren’t there, this is what it was like after I’d poked most of the mud off so the wheels would go round.

It seemed to be the combination of mud and grass that finished it off. I’ve ridden through plenty of mud before and the gaps between the pulley teeth work well, allowing the mud to escape.
Several times at SITS, there would be a sudden tight spot on the cranks, followed by a crunching noise as small stones got trapped between the belt and pulleys.
I don’t know if this is the one that did it, but it was the biggest of about 30 that I pulled out after the belt broke.

Wedged in the belt.

After pulling it out.

The broken belt.

I still think it’s a good system, although I have proved it’s got it’s limits.
There were plenty of people pushing bikes with smashed rear derailleurs, so in that respect, I was no worse off.
The difference is that they could bodge a single speed to get home, then buy a new derailleur from any bike shop.
I had to walk back and I’ve now got to order a new belt from gates.

Ouch

Would/could you still have the small stone problem if it wasn’t a centretrack type belt?

Slight redesign
Loose the center groove
More off an undercut on the pulley
Or drill an escape hole in the tooth root
Any way of a scraper or brush to help clear debris

Its been interesting to follow from an engineering point of view

Not sure if they are still doing dev work but you could try sending it back to here;
http://www.gates.com/europe/brochure.cfm?brochure=7867&location_id=11505
Just along the road from me 🙂

i broke one, not ct but the other one, i think it was down to wrong tension for me though, ive got a year so far though out of my ct one and its still running strong. noone said they were indestructable but they definitely work better than a chain. the worst thing that can happen to a belt is twisting if incorrectly tensioned it can twist upon picking up shit. its just a bastard they cost so much. out of interest graham did you buy the gates tool to remove the sprocket?

Loose the center groove

How do you propose keeping the belt on the pulleys then? Double flange on the pulley will cause even more crud to get caught up in it. The point of the Centretrack is its open, to allow crud to squeege out. Massivly unlucky to get a little stone in it Graham. Something similar did the Milkbike prototype at a race in Thetford IIRC.

The solution is, don’t go riding in such horrid conditions (which if it wasn’t a race, would you?)

My Carbon Drive belt:
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DSC_0293[/url] by ir_bandito[/url], on Flickr

I’ve had no probs with my Centretrack at all.

http://www.carbondrivesystems.com/support.php?lang=us

“Can I carry a spare belt with me on the trail?

Yes, you can carry a spare belt with you out on the trail. The spare belts are sold attached to a cardboard disk; it is recommended that you keep the belt attached to the disk for protection while in your pack.
”

If anyone could break it, you could Graham 🙂

What we need is some sort of metal belt, with ‘plates’ between which some sort of toothed sprocket can fit, and ‘rollers’ or sorts to reduce friction.

These metal-belts could be impervious to the sort of tiny stones that are everywhere, and if the idea caught on, I can envisage a range of them being available.

Even if they should fail I suspect folk could design some sort of powered link to rejoin it in situ, saving a long walk for mere pence.

Alas, such drivetrain panacea remains the stuff of dreams.

njee20 – 😆

What we need is some sort of metal belt, with ‘plates’ between which some sort of toothed sprocket can fit, and ‘rollers’ or sorts to reduce friction.

These metal-belts could be impervious to the sort of tiny stones that are everywhere, and if the idea caught on, I can envisage a range of them being available.

Even if they should fail I suspect folk could design some sort of powered link to rejoin it in situ, saving a long walk for mere pence.

Alas, such drivetrain panacea remains the stuff of dreams.

There’s always one.

On my Rohloff bike I’ve had a similar problem in similarly horrific conditions, with tight spots in the crank revolution developing, presumably due to mud packing onto the chainring and sprocket, increasing the effective chain length.

How tension-critical is belt drive? I find one solution I’ve used (if I know I’ll be riding in an utter mudfest) is to back chain tension off a bit to allow for all the crud that will stick to/in the drivetrain.

How tension-critical is belt drive

Very with the Carbon Drive, due to having to stay against the opposing side-flanges on both pulleys. But I’ve found using Centre-Track it doesn’t need to be too high. Like a taut chain perhaps.

Hang on OP did I miss something?

It costs a small fortune, your’s lasted only 1 month before snapping, spares are not very readily available, its less tolerant of miss-alignment, ‘incorrect tensioning’ and it seems also heavy mud, and yet you’re happy with belt drive???

Other than reduced weight I’m really strugling to see any substantial benefit…

Thus I must call:

Or is that a touch harsh…

I run a Rohloff with a chain on my off road commuter and it’s currently 4 years old. It’s never been cleaned in that time it just gets an occasional wipe over and gets covered in whatever oil is lying around, currently Toyota gearbox oil. The only real advantage I can see with the belt is weight. Gates claim that both pulleys and belt together weigh the same as a typical chain.My bike is a pretty heavy build and I’m not concerned about weight on this particular bike. I would one day love to build up a lightweight hub geared bike and then I’d look at a belt drive. Pretty easy to carry a spare belt.

It costs a small fortune, your’s lasted only 1 month before snapping, spares are not very readily available, its less tolerant of miss-alignment, ‘incorrect tensioning’ and it seems also heavy mud, and yet you’re happy with belt drive???

IIRC he’s been running it a lot longer than a month, he’s just been commuting for the last month in the rain/mud on it. You can cary a spare (MTQG didn’t). My chains aligned on the SS, not exactly rocket science. And I’ve snapped SS chains due to insuficient tension (the chain managed to pull/bounce off, possibly due to a stone, presumably bent a link slightly, snapped a few miles later, then snaped again a few weeks later).

Whilst I can’t see belt drives taking off due to price mainly, I can see their advantages.

I really want the Trek District Carbon, which comes with belt drive, just not sure I get the idea of using SS to reduce cots, then sticking a belt drive on it. Then again I guess they’re more popular with blinglespeeds and hub geared folk.

I’m still not convinced off-road though.

I dunno if I’m convinced either, £70 odd to replace belt and cog 😮