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Adaptive Cycling: Handcycles, Amputee Adaptation, Visual Impairment, and Other Needs Have a need for adaptive equipment to ride to compensate for a disability or loss of limb or function? This area is for discussion among those of us in the cycling world that are coming back from traumatic circumstances and tell the world, "No, you are not going to beat me down!"

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Old 11-18-12, 10:43 AM   #1
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Modifying Pedal rotation for 4 year old with delays?


I am looking at the weehoo i go pro for our now 4 year old son. He has delays in all areas and one of our therapists has him ride a tricycle with his feet attached to the pedals as we push and steer him around for the repetitive motion. This is not only hard on us, but boring for him which turns it into a battle. We actively go out biking and put him in an ibert child seat and he loves being out and about and riding on the beach. Would anyone know how we could modify the weehoo i go to have a gentle pedal turn while we are out biking so that he can have the therapeutic as well as the fun side? Here are two links for it: &

I have asked them directly, but they said they can not give out information on how to modify the bike trailer. He will be in a harness with feet attached to the pedals as you can see by the description of the weehoo.

We don't want this to be a permanent change as he will be able to do this on his own in the future, but for now, it is needed.
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Old 11-18-12, 06:35 PM   #2
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your question is not entirely clear.

From what I can see, the 'weehoo' is a trailabike style kids trailer, with freewheeling pedals for the kid. So if they wish, the child can do some pedalwork as well -but I doubt they'd be contributing much compared to the adult rider doing the pulling.

It sounds like; what you wannt to do is make the trailer no longer freewheel; as in no coasting for the kid pedals. Thus the child is forced to keep his feet in constant motion.
Is this what you are asking?

To do this, you will need to replace the rear wheel of the trailer with a 'fixed gear' wheel. You will probably need to have one custom built at a bike shop since it looks like the trailer uses a wierd size rim.
Just roll into a shop with the trailer, show them the wheel and say the words exactly:
"id like to rebuild this wheel on a fixed gear hub, with the smallest sproket possible on it"
probably cost between 100-150$ to do it.

I can fully understand why the weehoo makers won't tell you how to do this; frankly its pretty darn dangerous
the kid pedals will Always be moving as you ride, Suppose you start rolling downhill 20+mph and the kids knees burn out? There is much less control over what you do to his legs in this setup as opposed to manually pushing a tricycle.
if you do this; keep speeds as low as you were going on the trike.
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Old 11-20-12, 02:11 PM   #3
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It isn't to "force" him. He loves biking and going but doesn't have the complete awareness to hold his own feet on the pedals at all times. They even slip off the tricycle if a wrap is not put on around his feet and pedals. So, having them with velcro to help keep his feet on the pedals is very important and comes standard with the weehoo. Having the pedals turn slowly is to help with the repetitive motion and brain training needed to help him properly use his hips and legs which he is not currently doing. We have made a huge amount of progress as we were told he would never walk and he is not only walking, but working on running. However, without the proper movement in his hips, his gait is wrong and he has a lot of difficulty. (We have looked into gait training therapy but no one takes children anywhere near us. It is only set up for older adults for some reason so this is why the therapy is being done this way.)

We have beach cruisers and only do casual bike rides to the park or the beach. Not fast especially since we also have a 2 year old and I am 6 months pregnant with our third child. So with our normal easy and slow speed and having the bike trailer set up to pedal super slow, the idea is he will get to enjoy his bike rides without us hanging over the top of him (which is what makes him mad) while getting the therapeutic side he needs. We also live in Florida, so we are flat as can be so it is really just us taking short bike rides, get off and play, then hop back on to go home. Nothing more than 2 miles in total distance and at a very casual speed.
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Old 11-20-12, 06:31 PM   #4
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Interesting problem. A fixed rear hub combined with dropping the gearing to the Weehoo could get you their. Sounds like it could be done with existing parts.

It's the fixed hub that bothers me. If kid's feet slip off the pedals, the pedals are still spinning- a definite hazard. He's out of your eyesight. Maybe a side by side surrey?
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Old 11-20-12, 09:18 PM   #5
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I use the word 'force' purely in a bio/mechanical context

basically, the pedals will push the legs; instead of the legs pushing the pedals -is that what you want to setup?

I'm assuming yes, its the only thing that makes sense
so yeah, like I said earlier, replace the wheel with a 'fixed gear' wheel
this will make the pedals stay locked with the wheel as it turns; no coasting; constant motion so long as the bike is rolling.

really, as Flying Merkel said though; its can possibly be hazardous - machines apply unyielding force with no direct control as when you did this on the tricycle by hand. Feet slipping off and then getting whacked by the still spinning pedals is a good example. I'd also worry about the potential for straining/overworking his knees; since you won't have direct feedback anymore.
If it was me, I'd keep theraputic 'work' separate from recreation; since its serious business and needs the attention to detail.


I've seen tandem bikes; designed for child+adult. Typically they put the child into the front stoker seat and have the adult be rear captain.
I think modifying one of those is the right way to achieve your goal; since then the childs pedals can be directly synchronized to your own; giving very good control over the pace and force applied. also putting the child safely in view so you can be aware of any problems.
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Old 11-21-12, 05:32 PM   #6
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I hadn't thought of a surrey and don't know how that would go. I did think of a tandem bike first, but was having a hard time figuring out how to fix it specifically for our son. It would have to have a seat and harness system in addition to the pedals. I also don't know if I could balance us both that way as I can't ride a tandem bike with anyone else as my balance is thrown off.
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Old 11-26-12, 09:36 PM   #7
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Here is a thought, the rear wheel looks to be 16" or a 20". Also looks to have a freewheel, bmx style sprocket.
If you remove that and install a 3 - 5 -6 speed cassett, you could put the chain on a slow turn radius.
Lock the gear to the spokes. All that need be done from there is spreed the frame to take the wider wheel hub.
Oh, may also need longer axel and spacer for the wider sprocket.
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Old 12-08-12, 11:47 AM   #8
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My first thought was the Buddy Bike tandem, if IPV can be added to this (to allow child to freewheel if needed), but that would not work if the adult's balance gets thrown off.

Not sure if this tricycle product would work for a child this age, might need to be a bit older.

There is a list of 20 bikes for children with special needs here

Ambucs has various foot attaching gadgets for attaching feet to pedals.

For home therapy, a device like this might provide opportunities to work those muscles.
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Old 12-14-12, 01:56 PM   #9
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Are you anywhere near Minneapolis MN? If so,I may have what you need. I'm not using it anymore for kid hauling.

Stoker will always spin at the rate the captain does, (or some percentage thereof with different timing rings.) Whether pedaling passively or adding propulsive force.

The kiddie crank unit is on loan but I can probably get it back. I could add another set of pedal holes for shorter legs.

My business is shortening cranks for special needs, kids and triathletes. I just made a set for the back of a tandem with holes at 57 & 77mm for a 4 yo. dwarf with a 9" inseam.

If you are interested, contact me off list or 612-824-2372.

BTW I know it looks a bit "Home Made" but you don't need to worry about build quality. I've been building custom bike frames since '79.
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Old 12-30-12, 11:48 AM   #10
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Originally Posted by MnHPVA Guy View Post
Are you anywhere near Minneapolis MN? If so,I may have what you need . . .
A bit of context may be helpful. Mark is well known for his craftsmanship and willingness to go out of his way for fellow cyclists.
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Old 12-31-12, 11:46 AM   #11
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Originally Posted by gcottay View Post
A bit of context may be helpful. Mark is well known for his craftsmanship and willingness to go out of his way for fellow cyclists.
Thank you both. For some reason, the email feature that tells you when there is a response didn't email me on Mark and just did now on gcottay so I didn't even now you both had responded.

Thank you Mark and I will email you to speak with you further. Thank you for taking and interest in helping us out!!!
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Old 03-23-13, 07:32 AM   #12
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I agree, under the wrong circumstances the fixed gear solution would be an issue.

As you are looking at developing the range of motion, not the cadence and spin of
a road cyclist the rate crank rotation from the Wehoo rider does not have to be in
rhythm or synch with the captain, as it would on a tandem.

Re gear the Wehoo into something with an ultra low gear setup.

Using some custom modifications, you could get the gearing down to something
that may spin at 50rpm( or less) at 20mph.

That way, your Wehoo rider does get the slow steady movement, but will not
experience fatigue from constant spin, especially in the early riding stages.

The ability to modify the gearing would be helpful.
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Old 03-23-13, 12:04 PM   #13
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.02, noting a newer hub made by Sram, offers a screw in fixed- freewheel option,
so having a screwdriver along , would let the change happen mid ride..

what caught my attention was the use of a driver that took 3 speed cogs .. cheap and commonplace.
13 to 22t.. so that (and a fixie velcro strap on the pedals ) would be a possible wheel build upgrade.
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