Steve Mercer IOM TT Rider needs help

[531colin]

………….(A shorter crank on one side is no answer because while it is less of a reach at the bottom of the rotation it is more of a reach at the top)

a pedal on a shorter crank is always closer to the bottom bracket than a pedal on a longer crank
....so on a shorter crank the pedal is higher at the bottom and lower at the top.
This might suit somebody with for example a shorter leg, or reduced joint flexibility.
Specialist companies make rather more complex (pivoted, etc.) cranks which can be set up in all sorts of ways; for example to have the same reach at the bottom but less reach at the top.

[pwa]

………….(A shorter crank on one side is no answer because while it is less of a reach at the bottom of the rotation it is more of a reach at the top)

a pedal on a shorter crank is always closer to the bottom bracket than a pedal on a longer crank
....so on a shorter crank the pedal is higher at the bottom and lower at the top.
This might suit somebody with for example a shorter leg, or reduced joint flexibility.
Specialist companies make rather more complex (pivoted, etc.) cranks which can be set up in all sorts of ways; for example to have the same reach at the bottom but less reach at the top.

Effectively the aim must be to do something to make it as if there were two bottom brackets (left and right), one higher than the other, and the higher with a shorter crank. Each foot does a circle but one circle is higher than the other. Built up shoes or pedals must be the simplest way of doing that. But detailed knowledge of the individual would be needed for a proper solution.

[531colin]

Effectively the aim must be to do something to make it as if there were two bottom brackets (left and right), one higher than the other, and the higher with a shorter crank. Each foot does a circle but one circle is higher than the other. Built up shoes or pedals must be the simplest way of doing that. But detailed knowledge of the individual would be needed for a proper solution.

https://www.quest88.com/
Go to "adaptive cycling" page 5, look at pendulum pedal

[pwa]

Effectively the aim must be to do something to make it as if there were two bottom brackets (left and right), one higher than the other, and the higher with a shorter crank. Each foot does a circle but one circle is higher than the other. Built up shoes or pedals must be the simplest way of doing that. But detailed knowledge of the individual would be needed for a proper solution.

https://www.quest88.com/
Go to "adaptive cycling" page 5, look at pendulum pedal

I will when I have a bit of time. The more I think about it the more complex it seems as a mechanical challenge. Normal symmetrical cycling works on the assumption that both legs are roughly the same and gives them the same job to do. The same circle at the same height and the same fore-aft position. if the legs are significantly uneven you need to get away from that. I will follow the link with interest Ta.

[[XAP]Bob]

Higher crank being shorter is a tough one - but something combining aspects of the k drive and pendulum crank might do the job.

[Vorpal]

We've had similar threads in the past....

viewtopic.php?f=49&t=120488&p=1214014
viewtopic.php?f=5&t=106325
viewtopic.php?f=1&t=93444&p=857134

[hondated]

Thanks again everyone for your advice. I have copied the link to Steve and as soon as I learn he is back on the road I will let you all know. He's a tough fella so that shouldn't be too long Ted.