# Retroflex Crank Adaptor



## flatflr (5 Mar 2016)

Hi All

After some advice here.

A friend who broke both his legs really badly (lost about 2 inches of bone from each femur which has been regrown and has only just started to walk after about 3 years) has been advised by his physiotherapist to use a bike on a turbo with short crank due to limited knee bend.

He's been looking at a Retroflex Cycle Adaptor (as below). Does anybody have any information on these?






Cheers

Flatflr


----------



## Bollo (5 Mar 2016)

I've memories from many years back that a forumer's other half had a bike with something like one of these. I'm thinking @Cunobelin but it's a punt. Apologies if I've got it wrong.


----------



## Sharky (5 Mar 2016)

No knowledge of retroflex, but Promax do some short cranks. Again no experience of the latter.
http://www.dccycles.co.uk/promax-sq-1-chainset-10444-p.asp

I have some SINZ cranks, but not sure if they are still in production, but have been very good.
e.g. http://www.sourcebmx.com/en/gb/Sinz-Expert-Square-Taper-Race-Cranks/m-30255.aspx

Or have your own shortened
http://highpath.co.uk/
Have had two pairs shortened by this firm. They also offer other options.


----------



## ufkacbln (6 Mar 2016)

Bollo said:


> I've memories from many years back that a forumer's other half had a bike with something like one of these. I'm thinking @Cunobelin but it's a punt. Apologies if I've got it wrong.



Almost, I adapted with pedal spacers that moved the pedals out rather than shortening the cranks

This was a solution for us because by wife had outward deflection in her knee joints

The Retroflex will induce a wider "Q factor" that will widen the feet placement, and can be uncomfortable if you have straight legs

The other question is which type of shortener you want.

The first is a simple attachment (this is the Hase one)





IT shortens the crank length but pedalling is the same basic method

The second (which the Retroflex appears to be) is a "pendulum" These shorten the crank length, but the pedal has a second rotation altering the pedalling motion and technique (again the Hase version)






The end of this video demonstrates this



Sorry if this is confusing rather than a simple answer

There are a number of sites and companies that specislise in these adaptations and can give advice


----------



## flatflr (6 Mar 2016)

Thanks for that, I'll pass it on to my friend.

He's not to worried about it being a bit wider, he's lucky to still have his legs (both compound fractures and a fused knee after being in frames for so long), walking is a big step for him at the moment.


----------

