Superlight Alfine

This one was an interesting challenge – an Alfine 11spd belt drive bike with a goal weight of under 7kg (15.5lb), so it would be easy to carry up stairs in the city.  The original flat-bar specification met this goal; a late change to drop bars increased it a little, but the final weight is still very good at 7.6kg (16.7lb), complete and ready to ride.

To keep the bike compact, for ease of storage and maneuverability, the seattube has a curve to allow the chainstays to be shorter. With the belt drive, there of course needs to be a way to tension the belt, and also to install the belt into the rear triangle. Neither an eccentric BB or sliding dropouts were a good match for the lightweight goal, so I needed to come up with something else. Having over 20,000 miles on my personal belt drive bike, I have learnt that once the belt tension is correctly set, it does not require further tensioning (and indeed, the Gates CenterTrack belt doesn’t need to be run very tight at all). So the solution I went with on this bike is mainly about allowing entry for the belt, with the chainstay length built correctly for the belt length being used. The end of the chainstay acts as a socket, sliding over a matching stub on the dropout. A 6mm bolt then holds it all together. Should a chainstay length adjustment be required, then it is simple to just add shims inside the socket as needed.

With the design for the belt taken care of, the shape of the frame was then chosen by customer preference, with the dropped seatstays coming in at the top of the curved seattube. The rear brake is under the chainstays, with the cables running internally. A Niner RDO seatpost is set at maximum extension for comfort on city streets.

Carbon tubulars might not be everyone’s first choice for city wheels, but shod with 25C Continental tires, the Enve SES 3.4 rims are a durable, lightweight choice. An Alchemy ELF front hub gives a nice match to the Alfine rear.

The remaining build has Versa dropbar shifters, THM cranks, ee-cycleworks brakes, Enve bar and stem and KCNC titanium pedals.

And then onto the paint! This was an iterative process to go from the customer’s concept to the finished bike, but Eric at Colorworks did a fantastic job of making it all come together. And of course, thanks to Tina Buescher for the photos!

One Comment

  1. Excellent bike! Doing my search since hopefully by the end of this year I will order my gates-bike . English cycles looks convincing and personal contact with customer is excellent to look at. PEACE to all!

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  1. Yishai’s belt drive bike | English Cycles - […] built Yishai’s bike back in 2013. At 16lbs it was the lightest Alfine hubbed bike I have built. However,…

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