Efrat’s 650B road/gravel bike

Shorter, light women are still very underserved by the bike industry. Although frames are produced in small sizes, their geometry is often compromised because they share forks with bigger sizes. And production bikes have to be built to cope with a heavy rider as the designers don’t know who will be riding it. Thus for a light rider the frame will be overbuilt and likely to ride harshly. This is why I love to design and build custom bikes for these riders!

For Efrat’s bike I was able to work with the frame design and geometry to ensure she would have the fit she needs, but not have any toe-overlap with the front wheel, even with 650B x 38mm tires. The tubing is relatively ‘undersized’ by today’s standards, so that it will have good ride characteristics for her weight. A custom fork was needed to get the amount of rake required for the design, and a custom stem was requested to match.

The flatmount disc brakes have custom made mounts front and rear, with the rear cable running internally through the downtube. Shimano Ultegra Di2 takes care of shifting duties (great shifters for small hands). One request was to have a quiet freehub – so the rear hub is a sprag-clutch model from Onyx, painted to match along with the DT front hub. The NoTubes rims were specially stripped and polished, then shod with Compass tires.

Colorworks did a great job with the subtle ‘autumn leaves’ motif of the paintwork, and thanks as always to Tina Buescher for the photos.

6 Comments

  1. hi Rob!

    interesting beautiful bike!

    yes, those tubing look “undersized”, especially the seat stays – veeery thin.

    maybe the rake is a secret (to get the desired trail), if possible i am really curious about the head angle and specially about seat angle – which looks steep, but maybe it’s just a visual illusion.

    the handlebars look like FSA New Ergo shape. for small hands wouldn’t be better the Compact shape with its smaller drop? or it was her preference..

    best regards,
    Mircea

    • well if you’ve looked at his other builds all the seat stays are thin since they’re in compression it will be fine, and once the wheel is locked in there it becomes really quite laterally ridgid.

      As for the seat tube angle, likely what is going on is the rider has really long legs in comparison to their torso, but the castor angle is basically fixed to keep the same handling characteristics, so the other way to shorten up the reach is to use a short stem (which it is already), use a straight seat post (which it is already) and to keep the drop bars at that height and angle the only thing left is to change the seat tube angle.

    • Hi Mircea,

      The seattube angle is set to position the saddle correctly for the required setback – in this case that angle came out at 76 degrees. For the front end, with the relatively short (85mm) stem, I wanted 60mm of trail. To achieve this whilst maintaining toe-wheel clearance the bike ended up with a 70.5 degree headtube angle and 54mm of rake (381mm axle-crown fork length).

      Handlebars are FSA SLK compact, in a 38cm width.

      thanks,
      Rob.

  2. Rob, thank you very much! interesting numbers.

    Chris, i know that all the seat stays are thin in Rob’s creations, it’s just that for this particular bike they look even thinner.

    regards,
    M

    • Yeah, now that you mention it they do look thinner than on other bikes he made. That’s the beauty of custom (purpose) built stuff

  3. Love this bike – stunning proportions just go to show how compromised some riders must be on stock bikes. Great color scheme and good to see someone having a go with brown bar tape and saddle. It works.

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