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We recently bought a recumbent tricycle second-hand for our special needs daughter (catrike pocket). The bikes pedals are a little bit out of reach for her (~4 inches). These bikes are expesive and we purchased it knowing that it did not fit her currently but that she would grow into it.

We can sit her a little further forward with some foam in the seat but the pedals at their farthest in rotation are too far. The pedals are also adjustable but not short enough still.

It was suggested that I could use some wood blocks attached to the pedals but that idea raises more questions i.e. I should put blocks on both sides of the pedals in case she loses grip and can find them again..

Are there any other DIY suggestions on how I can make the pedals accessible to a rider whos legs are just no long enough yet.

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    I've seen the wood blocks done (though not on this style bike), and it seems to work OK in some cases. Yes, the blocks should be on both sides, if only to balance the pedals so the block isn't always pointing down. – Daniel R Hicks Sep 24 '20 at 2:56
  • That is a sweet-looking bike. Another off-the-wall idea is to push her using the shoulder mountpoint as somewhat of a hand-rest. She could sit cross-legged on the seat and simply has to deal with steering and perhaps braking for now, with a view to pedalling as time goes on. – Criggie Sep 24 '20 at 3:01
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There are always options.

catrike image From OP's link, showing boom and bolts.

  1. Shorten the boom, if you can. There are two pinch bolts in the main frame, under the boom Back them both off and see how much can be inserted into the frame. You probably already did this, but revisit it and see if there's extra length to be saved. Perhaps the inner tube bottoms out, and you can get some distance back by trimming the end that is inside the frame.

    Downside Its really hard to extend again in the future, so be miserly at cutting. Or try the other options before whipping out the grinder.

    Trike boom being adjusted
    from https://tadpolerider2.wordpress.com/tag/tadpole-trike-boom-adjustment/

  2. Block the pedals with wood. This will get you closer, but the full distance would need 4 inches / 100mm of wood on each side. Example:
    Child's tricycle with wood blocks screwed into both sides of the pedals

  3. Shuffle the seat forward even more. Hard to be detailed without knowing how your seat is mounted. The backrest can often be adjusted for tilt but that doesn't move the hips forward which is required. You might find that reclining the back counterintuitively helps push the hips forward.

  4. Thicker cushion - Adding a "tailbone cushion" between the hard and soft layers of seat might buy you another half-inch or 12mm perhaps.

  5. Crank shorteners - the cranks are not the problem, its the distance to your bottom bracket (front bracket?) and therefore the pedal the farthest away from the rider. There exist bolt-on crank shorteners which will move the pedals closer to the BB axle line, effectively bringing the frontmost pedal back a bit.

    Shorter cranks are common on recumbents.

    Crank shorters

    1. You can also drill and tap cranks to make them shorter permanently, though this is risky and requires some excellent machine shop skills to get the hole angle right, and the threads tapped in straight. My adult sized `bent has 160 mm cranks, which were professionally shortened by a previous owner and you have to look hard to tell. Depends on having enough metal in the right place too.

      Most pedals are 9/16" thread with 20tpi which is weird (18tpi is common but incompatible) and only common on bikes, and the left pedal is left-hand thread, ie backward. So its not a home-shop job.

      Given this is a kids bike, it may also have 1/2" pedal threads, though your specs link doesn't say.

      Crank arms with additional tap


      More info at https://bicycles.stackexchange.com/a/64370/19705

You don't want to use swinging crank adjusters like the Pulse Swing Cranks; they will do the opposite of what you want.

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    Crank shorteners or shorter cranks for the time being may be the best solution. No way would I drill the cranks, they may be hollow in that position and it would be problematic to have the holes at the precise same position without pro-workshop tooling. – Carel Sep 24 '20 at 7:23
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    I suspect a very thick block of wood on the pedals might feel rather awkward pedalling, due to the displacement of the foot from the rotation axis, but up to about an inch would be good for fine tuning – Chris H Sep 24 '20 at 8:24
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    @ChrisH concur - the estimated need was 4 inches, and I can't think of one way to get all of that (other than perhaps shortening the boom by trimming the inner part, which is a one-way change. Get one inch in each of 4 places and we're there. – Criggie Sep 24 '20 at 11:03
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    Contact the builder who might know of a way to slide the seat further forward. There could be a workshop in your region that adapts vehicles, tools, ... for special needs people who can help with an extension of the seat rail. – Carel Sep 24 '20 at 16:21
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    @Matt the wood blocks - you would put one on either side of each pedal so they're still weighted/balanced. I wouldn't put 4" of wood on each side though, perhaps 1" and then look for 3 more inches elsewhere. Every little bit adds up. – Criggie Sep 25 '20 at 22:15

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