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Discussion Starter · #1 ·
I'm having problems getting the belt on my Pipedream Skookum rigid 29er to stay put. Unless I tension it to 85hz it jumps on steep climbs and until I recently aligned the pulleys the belt was jumping off. Anyone else had similar problems? These CDX belt drives seem really fiddly to get set up right.
 

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Seems that lots more people are using belt drive, but like cr45h said, sticking' with a chain.

Hopefully you can get it sorted...good luck.

SPP
 

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Discussion Starter · #4 ·
Postscript to this one - the belt snapped yesterday whilst out on the trails in North Wales and I had a long walk back to the van. I've contacted the shop who built the bike and will probably convert to chain drive. Love the belt drive concept but not convinced it is up to singlespeeding off road, at least not on a steel frame. It might be OK on a super stiff aluminium frame.
 

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Postscript to this one - the belt snapped yesterday whilst out on the trails in North Wales and I had a long walk back to the van. I've contacted the shop who built the bike and will probably convert to chain drive. Love the belt drive concept but not convinced it is up to singlespeeding off road, at least not on a steel frame. It might be OK on a super stiff aluminium frame.
Need more info! Is this the newer center track design? From what I've read, the centertrack design is much more tolerant of mis-alignment and does not need as much tension as the older system.

Sounds like there are a couple of issues. First, your beltline wasn't straight to begin with, and that caused the belt to jump off, is that correct? If yes, the belt gets damaged when that happens, that's why it snapped on you. Also sounds like the bike was not set up properly by the shop if the beltline wasn't correct, they should be replacing that belt for you at no charge! I'm not familiar with the frame you have, but if it has a belt split, it should be stiff enough, but I guess you never know.

Let us know what happens.
 

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Sorry to hear that about your belt. There is some set up time to get the belt set up right. Most shops do. Have a clue follow gates instructions to a tea. I have 4 years on my belt ad going strong still. Belt line and tension is key.
 

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Discussion Starter · #7 ·
image.jpg image.jpg image.jpg It's a CDX drive, here's some of the email I sent to the shop explaining the problems with the bike:
"There were two problems with the bike build:
The two drive pulleys were not aligned, as supplied there was a 3.5mm offset between the front and rear pulleys (measured with both pulleys parallel). According to Gates the pulleys MUST be exactly in line with each other. I fixed this by reversing the offset rear pulley which then set the pulleys in line with each other
The front pulley was not centred on the crank arm spider with meant the belt tension varied by more than 40Hz leading to slack and tight spots in the belt. I centred the pulley by progressively loosening and re-tightening the pulley bolts whilst testing the tension at multiple points on the belt
There was a third issue that I could not overcome, with the belt tensioned to the recommended tension the wheel axle is pulled downwards in the dropout (or the frame upwards off the wheel). It is not possible to tighten the axle sufficiently in the frame using a QR to prevent the axle 'walking' under maximum torque on steep climbs. On one occasion this led to me going over the handlebars and landing on my face on the tarmac after the rear wheel came out of the dropout and the belt came off. The belt has come off due to the axle 'walking' on more than six occasions. A nutted or through axle might overcome the problem. Alternatively a revised dropout slot which keeps the belt tension constant at all positions might help."

It was built with 39 x 21 pulleys which resulted in a short belt length and reduced contact area on the pulleys. We'll, it's getting converted to chain drive and at least I'll only need to carry a spare link in future...
 
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