Author Topic: bike pedal for my disabled son  (Read 3066 times)

Offline Andrew Wildman

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bike pedal for my disabled son
« on: August 16, 2015, 03:09:12 PM »
My son has got his first proper bike.  He had a stroke when he was a baby so one side is a bit weak and one leg is a bit shorter than the other.

I wanted to make him a pedal that offset the leg difference and also that we could fix his foot to to stop it sliding off during use.

The main body of the pedal was 3d printed with bearings pressed in and a counter weight fitted to the bottom to keep it the right way up to help him put his foot on it:

 showing old and new:


A spindle was machines and flats machined to allow it to be fitted.  Luckily it was the RHS pedal that needed changing so I could you a standard rh thread die rather than faffing with single pointing the thread:




Completed pedal without strap - I will post some shots of it in action when my son is next out on his bike!



Offline philf

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Re: bike pedal for my disabled son
« Reply #1 on: August 16, 2015, 04:27:11 PM »
Andrew,

Nice job - It's one of the few really useful things I've seen made on a 3d printer.

I hope he gets as much enjoyment out his bike as I do out of mine.

My slight worry is the pedal spindle. Many years ago I was riding up a hill near Stoke on Trent about 30 miles from home. I suddenly found myself lying in a heap in the middle of the road. Puzzled as to what had happened I got to my feet only to find my pedal still strapped to my foot but no longer connected to the bike. The spindle had snapped at a sharp corner adjacent to the boss with the two spanner flats on it. These were very expensive pedals and I think maybe the first to use sealed ball races. If I'd ever had need to take them apart I'd have seen the weakness and not used them. Your spindle has a sharp looking corner. It would be better with a decent rad in the corner and a suitable spacer. Another alternative would be a needle roller on the inside with a much larger spindle at the crank end tapering gently to the outer diameter bore.

If he's not going to be doing lots of miles it'll probably be fine. I used to do 200 miles plus per week and I weighed around 13 stone. (2 stone less than I am now!)

I'll never forget the 30 mile ride home pedalling with one leg.

Cheers.

Phil.
Phil Fern
Location: Marple, Cheshire

Offline NormanV

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Re: bike pedal for my disabled son
« Reply #2 on: August 16, 2015, 04:51:53 PM »
I met a chap in Kenya, who competed in bicycle races, who only had one leg! He was an inspiration.
Andrew, I am sure that your son will appreciate what you have made for him.

Offline Andrew Wildman

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Re: bike pedal for my disabled son
« Reply #3 on: August 16, 2015, 05:05:37 PM »
thanks all,
Phil, if the spindle was for an older child or an adult I would have made the whole spindle with a much bigger diameter, with more care to avoid stress raisers and with something a bit better than scrapbinium and 50p bearings.  He is only 6 so I hope he won't be punishing them too much! :coffee:

Offline Brass_Machine

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Re: bike pedal for my disabled son
« Reply #4 on: August 16, 2015, 09:16:29 PM »
Wow what a great project and a fantastic outcome. Great use of the 3D printer.

Good job.

Eric
Science is fun.

We're all mad here. I'm mad. You're mad.

Offline jcs0001

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Re: bike pedal for my disabled son
« Reply #5 on: August 16, 2015, 10:11:33 PM »
Andrew:

Great idea and work.  Are you planning a moderately loose strap across the centre?  The reason I ask is that my wife and I cycle quite a bit and I'm using one of the "snap in place" pedal/shoe systems however my wife was never comfortable with it.  Instead I picked up (bought) a commercial strap that goes diagonally across the pedal - they are called powergrips and are made up of a fairly stiff kevlar.  They allow the foot to go in at a bit of an angle and once the foot is turned to go across the pedal it tightens the grip on the shoe.  They will work with pretty much any kind of shoe.  My wife has used them for years and is quite comfortable with them.

Here is a short review:

http://www.tiredofit.ca/2012/07/11/powergrips/

You may be able to fabricate something similar for your son's pedal(s).

John.