Etc - Narrow q factor cranks Obree style

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Narrow q factor cranks Obree style

Printed From: BHPC Forum
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Forum Name: Etc
Forum Description: Any other riding-related topics
URL: https://forum.bhpc.org.uk/forum_posts.asp?TID=6881
Printed Date: 27 March 2026 at 4:09am
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Topic: Narrow q factor cranks Obree style

Posted By: speedy7777
Subject: Narrow q factor cranks Obree style
Date Posted: 08 April 2019 at 12:44am

I have been wondering if people here have made bikes with very narrow q factor cranks like Graham Obree had on his washing machine bike. Wouldnt it make a recumbent both more aero and also put the pedals in a more advantageous position for pedaling? if the flying scotsman film is true.

Just been thinking about it while pedaling along and it feels like my legs would preffer to pedal closer together.

Could you suggest an easy way to modify a standard cranks (104bcd) / BB/ BB shell to experiment with it without spending a heap of money on it? or what off the shelf parts would achieve it.

The narrowest bb for my cranks is about 108mm ( octalink dura ace) but i dont think thats narrow enough to make much difference. Current bb is 113mm.

Are any rear suspension recumbent frames (or even a round tube boom only) made from new like that?

Replies:

Posted By: JDub
Date Posted: 08 April 2019 at 9:46am

Yes, narrow BB makes sense in every way. I made square taper axles from silver steel and used TA sealed bearings and cups. Quite a lot of work. This in Notso, which has a narrow steel shell. Most other solutions have less standard components. Kingcycle Beano for example I favour TA Cyclotourist cranks as they have a low Q. Not many available now. I have a plan to make steel tube cranks. Have faced the pedal thread area and cut back the shoulder on the pedals. Gained a few more mm.

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jdub... Got the T-shirt
http://protobikes.org.uk/
https://www.flickr.com/photos/150386999@N02/

Posted By: JDub
Date Posted: 08 April 2019 at 9:49am

My axles are 81mm long. Royce will make them for you - at a price!

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jdub... Got the T-shirt
http://protobikes.org.uk/
https://www.flickr.com/photos/150386999@N02/