Casey’s singlespeed road bike

Casey’s singlespeed road bike

Casey set me an interesting challenge. He wanted to have a lightweight, singlespeed road bike, but with the ability to change to a slightly lower gear whilst on the road. He also wanted the bike to be adaptable to an eTap rear derailleur in the future. And he requested the rear brake to be under the chainstays.

I had a few options on how to accomplish all this. In many ways the simplest would have been to use an eccentric BB, but this would not be easy to adjust if changing the gear (and thus the chain tension) when out riding. Doing a dingle speed (2 chainrings and 2 sprockets with the same chain length) was possible, but means extra parts on the bike that may not be used. Adjustable dropouts would work, but be a bit balky and un-needed if gears are added. Eventually I settled on using a modular dropout – I modified these to reduce the weight and to allow for tension adjustment screws with the track inserts installed. This allows the use of a quick release rear wheel without danger of it slipping, and the thumb screws mean quick and easy tension adjustment at the roadside. Then in the future, the track inserts can just be swapped for the vertical/derailleur inserts and gears can be added.

With the dropouts worked out, I then had to look at the brake – being located under the chainstay means that it is subjected to the most movement of the rim when the chain tension is adjusted, and to allow for different gear combinations I needed more adjustment than the slots in the brake arms would give. Making an adjustable mount was somewhat of a challenge owing to the very limited space between the innermost brake position and the bottom bracket shell. I wanted it to be a single bolt adjustment too. Ultimately I machined a slotted brake mount that keys onto a track brazed to the frame – this prevents the mount from rotating and locks it cleanly to the frame whilst providing the maximum adjustment that the available space allows.

After all that the rest of the frame was straightforward! An aero downtube, ovalised toptube and curved seatstays, with internal routing for the  rear brake.

The lightweight parts spec features a Lightning carbon crank, EE brakeset, Enve fork and bar, Ritchey seatpost and Tune saddle. Wolftooth provide the single 52T chainring and 17T and 18T sprockets. For the wheels, we discussed going with carbon rims, but with clinchers the weight saving over aluminium is minimal, so the decision to stick with alloy for the superior braking was made. The Vision Trimax 30KB wheelset goes one further by having a ceramic braking surface that improves braking – with the added aesthetic bonus of the braking surface remaining black. Custom cassette spacers were machined to fit the two sprockets to the standard freehub body, meaning that the same wheels can be used when an 11spd cassette is added.

Colorworks did their usual great job with the paintwork, and the final complete weight is 13.9lbs.



  1. cool bike! 😉
    the drop out does not look horizontal, is there a reason for that? (or i am seeing it wrong, like a photo illusion)
    thank you!

    • Hi Mircea – yes the dropout is slightly off horizontal; it was a small compromise between having the best angle for the track insert and the derailleur insert.

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