Bullwhip

11 Speed Belt Drive Snow Machine

November 20th, 2011

Some commuters are unstoppable, and our friend Matt was going through two chains a year commuting in snowy, slushy, salty and gross western Connecticut winters. He had the weather-proof solution: an 11 speed Alfine internally geared, belt driven, disc-braked super commuter, and I’m psyched he asked us to build it for him.

I’d done one belt drive before, a single speed, but the Alfine hub, coupled with the desire for fat tires, creates some new technical challenges. Belts are wider than chains, but more importantly they need to run perfectly straight – if not the belt will literally walk off the cog or sprocket. [This is one reason for the new Center Track system, which allows for more flexibility]

Even with chain drive, providing clearance for chainrings and wide chainstays can be a problem. Here, it’s worse – the belt is wider, the “belt line” has to be perfect, and to top it all off, the rear cog on an Alfine hub is set in away from the dropout, to accommodate the shifting cable. I did some fancy crimping of the chainstay, so here it is, built up with 26×2.3 tires, ready for action:

  

  

Here are some shots of the build in process:

  

When Matt and I began discussing this bike last year, we weren’t sure how best to break the frame (the belt doesn’t come apart, unlike a chain, so you have to be able to get it inside the rear triangle). Fortunately, Paragon came out with a belt option for their sliding dropouts. These are great for disc brakes, because the caliper stays aligned to the dropout, and for belt drive systems, as they have integrated tensioners. Belt tension is super important for proper performance. Here are some shots of the dropouts during construction, and of the frame before components. You can see how I weld on a section of tube, similar to how we do capped stays:

   

And here are some shots of me mocking everything up before the wheels were built:

   

And some of the completed frame. The Paragon dropouts are stainless, so I was able to polish the interface where the frame breaks:

   

And some more shots before components. Note, the bottom bracket below is just one I had lying around that I used to determine the alignment; in the complete bike pictured above, it’s a narrower Phil that fits properly.

  

Next up: Belt drive again, this time a single speed! And super-lightweight S3 tubing fever! Weld-o-Rama 2011 continues!

This entry was posted on Sunday, November 20th, 2011 at 5:47 pm and is filed under Everything Else. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

4 Responses to “11 Speed Belt Drive Snow Machine”

  1. Gordon Manson says:

    November 22nd, 2011 at 11:03 am

    Super nice. I haven’t forgotten about you guys. I have just been trying to get my finances all lined up.

  2. Henry says:

    December 1st, 2011 at 6:19 pm

    For the first time in 45 years I am excited about a new innovation in cycling. Ive always been old school, strictly steel frames with nice lug work and never saw anything appealing about carbon fiber but this carbon belt drive is a great idea for alot of good reasons. I’m ready for one. I’ll have to admit that i’v been looking at the Civia and Spot but honestly I would rather have one hand made in Providence where the paint jobs look outstanding and the frame work looks more like art!! Start thinking about a touring/commuter.

  3. Juan says:

    January 6th, 2012 at 12:47 am

    wow, that thing is wicked!!!

  4. admin says:

    January 6th, 2012 at 6:14 am

    Just got an update from Matt, he rode to work in 4 degree weather on Tuesday, and it shifted fine. Now I’m waiting to hear about snow…

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