A4 scale = 70%

  EGGring Ovals page 5   ...   Technical notes continued

Crank position / orientation

Your crank's position relative to an Oval's axes is crucial if the lowest gear is to be provided when your feet are at the dead-spots. The exact position is determined by the geometry of your cycle and your riding position on it. (We permanently mark every EGGring Oval with the correct crank position for its specified cycle and use.)

Power-stroke on an upright bicycle		Power-stroke on a recumbent

We calculate the amount your crank is offset from the minor axis from information you supply with your order. This offset has to be a compromise if you sit on the saddle at times and stand on the pedals at others, and a different value may apply to each chainring on double and triple chainsets. If you are interested in measuring the offsets for your cycle, do so as follows:

1. Park your cycle so that you can sit on it and pedal normally.
2. Select the middle rear sprocket and push the right pedal as far as you can, to the bottom dead-spot where you can transmit least power.
3. Ask a friend to measure angle a, as shown.
4. The crank offset is (90°- a). A +ve value indicates a retarded crank and a -ve value an advanced crank.  (eg. if a = 75°, offset = 90-75 = 15° retarded.)

		crank advanced		crank retarded

The following table gives typical offsets for various styles of riding:

© Chris Bell, 2006

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HIGHPATH ENGINEERING Cornant, Cribyn, Lampeter, Ceredigion, SA48 7QW, Wales, UK phone / fax:  +44 (0)1570 470035  (UK office hours only) email: