Buyer’s guide: bicycle geometry

A step-by-step guide to the tubes, angles, and profiles of the chassis of your next bike


With so much of the ‘package’ of a new bicycle taken up with third-party components, and with the previously discussed significance of the fork to front-end handling, it is sometimes surprising to see manufacturers use a fork from a third party. Gribaudo designed a new fork for the latest generation of Xelius EFI racing bikes, having used an off-the-peg Easton EC90 unit on earlier models.

Full carbon forks typically have tapered steerer tubes, offering the use of continuous, unbroken fibres

Steward concedes that there is an element of ‘blind faith’ in the selection of a third party fork, but believes the onus is on the product manager to select the most appropriate unit and to test it with the frame to check its handling. “We’ve got to the stage now where there’s so small a tolerance and difference in batch manufacturing that you’d be really unlucky to get two that would be wildly different and ride differently,” he explains. The Team Issue incarnation of Genesis flagship Volare is supplied with the highly-respected Enve Road 2.0 fork.

The tapered steerer tube is now de rigueur with full carbon forks. Greater breadth is placed at the bottom of the fork where the load is greater.  Tapering the steerer tube serves a structural purpose too, says Gribaudo. “Having a tapered steerer tube helps us to have a better continuation of the fibre between the lower leg and the steerer tube,” he explains. “If you go for a 1-1/8”, then from the crown to the 1-1/8” steerer tube you have kind of a 90-degree angle which is not good for the orientation of the fibre.”

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