free2b12

Have limited ROM in knees and thinking this might help.

And if so, where would I find the parts?

Rollfast

here are some important things to remember.

It isn't the crankset, but the seat post extension you want adjusted.

The most important thing to know is that you are only driving ONE SIDE in most tricycles I've seen. The other is freewheeling.

To maximize power from the stroke you need to have motion best suited to your legs' motion. If that can't work well enough you should consider a motor assist or drivetrain that uses your hands, or a recumbent.

AlexCyclistRoch

If it has an Ashtabula-type crank, you'll likely need a bottom bracket converter, to change it to a common square spindle, then you can choose cranks in any length.

thumpism 

One-piece Ashtabula-type cranks used to come in various lengths; 3 1/2", 4 1/2", 5 1/2", and 6 1/2". If it's an old Schwinn the bottom bracket threading is likely 26 TPI whereas non-Schwinn parts would be 24 TPI, complicating things. My suggestion would be to get it to a shop for an up-close look by an old timer, if you can find one.

Barring that, converting to a square taper spindle with the accompanying parts might be easier.

*edit*

Looks like new production, not "real" Schwinn so might be simpler to find something in one-piece.

Hawley distributors sells 165mm (about 6 1/2") and 175mm (about 7"), but for shorter you might need to find a juvie bike to strip at your local co-op. Little bikes generally have shorter crankarms.

https://www.hawleyusa.com/Catalog/Se...cat=5637146731

maddog34

have someone that knows how to adjust your riding position help you SET THE SEAT HEIGHT...

then, ride the bike, and see if you still need a different length crank set

There are many lengths of Ashtabula Crank sets available.... the shorter the crank, the more EFFORT it will take to move the bike, especially when first starting to pedal.....

cyccommute 

As much as I dislike praising Ashtabula cranks, converting to a different length is easier and cheaper than a cotterless crank. There are also many more choices in crank arm length. If nothing else, there are a vast array of old cranks out there from little kids bikes (120mm, 140mm) to adult bikes (165mm, 170mm, maybe 180mm). Even new ones are dirt cheap at less than $20.

Bill Kapaun

Having "bad" knees helps me realize your plight. Going from 170 to 165mm cranks made a world of difference. Like NO knee pain from some knee pain. (175mm was chronic knee pain)
A semi close pic of both sides of the crank would be useful to determine exactly what you have.

McBTC

How low do you believe you need to go and what do you have now? Ride2 Crank Arm Shorteners (available through Amazon) have 4 discreet lower settings so how low you can go will depend initially on what you have now. If you only need to go as low as 165, a new set of Shimano cranks isn't expensive if you plan to get years of use out of it but going lower than that is expensive as it involves buying equipment in the specialty market that whose customers come primarily from Triathletes who are looking for a competitive edge and are willing to spend the bucks to gain an edge on the competition.

thumpism 

Let's not drag common sense and practicality into this. If the man wants shorter cranks, let's give him shorter cranks!

I suspect if knee range of motion (ROM) is the issue then the original idea might be best. Has the OP consulted a physical therapist to evaluate the limitation?

Bill Kapaun

IF your knees don't bend as far as they used to or one as much as the other, you don't need a doctor to tell you. Your knee(s) will.

nfmisso

++++++


Now to the OP's question:
cranks: https://www.amazon.com/Sunlite-Piece.../dp/B000WY5QTY pick the length you want.

worst case, you may need this as well: https://www.amazon.com/Sunlite-Botto.../dp/B000AO9PBQ 24TPI to go with the cranksets above, 65mm or 68mm is the shell width of the BB housing on your trike. Scroll down to #2 on this page which shows how to measure: https://www.nashbar.com/webapp/wcs/s...bikeSpot_Part1

Jeff Wills

Uh, people... the Schwinn 26" Meridian Tricycle has three-piece cranks. Judging by the photos, they appear to be mounted on a square-taper bottom bracket.

Free2B... any decent bike shop should be able to help. Swapping crankarms is a straightforward job, but it requires some special tools.

Short crankarm pairs are available:
https://www.niagaracycle.com/categor...-arm-set-145mm
https://www.niagaracycle.com/categor...et-155mm-130mm
https://www.niagaracycle.com/categor...-arm-set-165mm
but you will also need a chainring to match.

cyccommute 

I'm not sure if that is always true. Before I posted, I checked and the bike I saw had Ashtabula cranks. Now I'm seeing ones with 3 pieces cranks. It may depend on the model year.

okane

Perhaps I just don't get it, but I have bad knee/back problems and can't ride without knee pain anything smaller than a 23" frame. This allows me to get almost full leg extension on the power stroke and limits how far I need to bend the knee on the upstroke.

What I am suggesting is that my rom is less than on a smaller frame because I don't need to bend the knee as much, i.e., my leg stays straighter throughout the cycle whereas with a smaller frame or crank arm I would start out with the knee already bent on the bottom of the power stroke and bend it even more on the top of the upstroke.

Someone previously mentioned seat height as a possible solution which makes sense to me (but I still need the larger frame as I am six feet tall and top tube length is too short on smaller frames).

For me, more knee bend is problematic. However none of the above applies if the knee condition is such that the person has a bent knee and cannot straighten the leg.

nfmisso

Ditto; must very by year.......so OP need pictures.