Obree tribute pursuit bike

Obree tribute pursuit bike

I had wanted to do this for a while – firstly to have a fixed gear TT bike to try on the local courses. Secondly to try out Obree’s aero positions – both his original tuck and the later ‘superman’. Fortunately I race in Oregon where the rules are not strict like the UCI!

The impetus to finally get it built was a project I did with Kingcycle last year, for which they designed and built a special narrow crank. I machined a custom BB and shell to allow this to be mounted in an eccentric for chain tensioning duties – this means the rear dropouts are vertical and the rear wheel will always remain nicely matched up to the cutout on the seattube. The Q-factor for the crank is 81mm. Having the pedals be this much narrower enables the BB to be dropped quite significantly whilst retaining the required cornering clearance.

Obree’s bike sported trispoke wheels for his hour record attempts, so I contacted the good folk at Hed for some help there. The narrow crankset moves the chainline inboard – to match this Hed were able to build a custom rear wheel with the sprocket mounting threads moved in, and the axle width reduced to 110mm. The front wheel was taken down to 80mm to continue the narrow theme.

The frame uses airfoil section tubing for the seatmast, with a custom mini-seatpost secured with an internal wedge clamp. The main tube was custom ovalised to fit up to the machined headtube, which uses a standard 1″ lower bearing with a special narrow radial top bearing. Chainstays and seatstays are tucked in as neatly as possible, then gussets were added to ensure frame stiffness and strength.

The handlebars/stem/steerer are all one-piece, in this initial configuration for the tuck position (I will build a different set later for superman). I got the bike finished in track mode for NAHBS, but a front brake will be added soon so I can take it out on the road and see if I can actually ride this position!

5 Comments

  1. Without a doubt this should have got the supreme award at NAHBS

    • This is a better thought-out and executed bike than Graham rode. I wonder how much farther he would have gone on an English.

  2. The cranks are fantastic (and the whole bike too, obviously)!
    Any chance they’d be available to buy?

    • Hi Alex, sorry but Kingcycle just made a limited number of cranksets. And they do require a custom frame with a special narrow BB shell and raised chainstays.
      thanks, Rob.

  3. How were the races?

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