Advice on tryke problem.

[wheelhorseman]

I am working on my new tryke. See it in fresh finds. I want to make it one speed because the old 5 speed parts are junk. How do I align the chain if I use one of the existing large sprockets? You cant shift that cassette over. The hub is on the axle via roll pin. The only idea I had was changing to a single 22t freewheel then align7ng the hub and welding in place. Does a chain have to run perfectly straight to work or can they run at a slight angle?

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[wheelhorseman]

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[wheelhorseman]

Another question. The bike has a 3 piece crank with 40t sprocket which is high gearing. Can sprockets on 3 piece cranks be changed? Would like 36t up front.

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[deorman]

Cottered crank sprockets are usually a permanent part of the right side crank arm. Snatch the whole crank-set off one of those trash mtb bikes that you can't sell. Straight tight chain won't work if the chain line is off by much, and a loose one will shift off, but a sprung tensioner that feeds the chain straight on to the rear sprocket can make unaligned sprockets work. An old derailleur would work.

 

[LukeTheJoker]

Deorman is right, the sprockets are welded on, but later square taper cranksets will usually thread straight in...

Luke.

 

[wheelhorseman]

I have the old rusted derailer but its trash. Are derailers universal? If I took one from an old mtn bike could I use it to help align the chain even tho you wont be shifting? I dont know which sprocket in back is the most in line because there's no chain yet. I wanted to use the 2nd. gear sprocket for the single speed. I have the shift handle that works but the cable is shot. Would it be hard to replace the cable and derailer enableing it to be shifted?

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[deorman]

If you mean the second smallest cog you can probably align it by screwing the outer (high gear) limiting screw, then screw in the inner one to limit possible inward motion. Most common derailleurs should work.

 

[wheelhorseman]

Doerman I was gonna go with the next to largest cog for best gearing. How hard do you think it would be to make it shiftable again? Would an old mtn bike ca ble and derailer work? I will load a pic of the shifter. Its kinda cool. Heres tho old POS derailer.

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[deorman]

I was just looking again at the pics, and I realized that I don't know how the der. fits on there. That looks like a standard 5-spd universal mount though, so a 6 or 7-spd uni from a cheap mtb should be usable.

 

[wheelhorseman]

Here the old shifter control. It works. Clamps around the handlebar stem. I am thinking it will be easier to make shift than making one speed ???????

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[wheelhorseman]

Doerman look at the cassette pic. See that rusty nut on left side below axle. Thats where derailer was mounted along with a smaller screw. Bike is upside down for pic.

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[wheelhorseman]

Will a modern 3 piece crank from a Wally bike fit the tryke? Want to replace with a smaller sprocket and longer arms.

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[deorman]

There is a high probability, if it's Asian then definitely. I doubt it's French, if so it wouldn't work. Is there a name on your shift components?

 

[wheelhorseman]

They are rusted to heck. I thought about having someone cut out the bb and weld in a bb for a one piece crank. Any thoughts on that? I went and looked. The bb is actually welded under the frame. A good welder could trim it off and weld a one piece bb on there in 15 minutes.

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[wheelhorseman]

Still looking for opinion about welding the bottom bracket to change over to a one piece crank.

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[RustySprockets]

My opinion, for what it's worth: Compare the existing BB with a three-piece cotterless taper crank. If the parts will fit, that's the route I'd follow. WAY easier than a one-piece transplant. I wouldn't write off the five-speed parts, either. As long as the teeth are sound, wire brush the heck out of those cogs, rinse them with lube and return them to service. The derailleur would be an easy replacement at my community co-op--maybe I'm just spoiled by our piles of parts. The shifter can be completely refurbished and the kinked cable housing replaced. I'm betting you could make this ride-able in one afternoon, with the addition of a new chain.

 

[rickpaulos]

A boxmart mtb will have all the parts you need to get it running. There are countless such bikes in the dumps all over. Our local coop has everything you need for $5 donation. Check your local bike shops for junk bikes they throw away. Many will be happy for you to get rid of those.

You can swap out the bb axle (use the same cups if the threads are different) and use the mtb crank. Cut off the rings you don't want.
I'm always cutting off the spare rings for single speed conversions. Look for a crank that has the ring size you want that is swaged to the arm and cut the others off. I use an angle grinder for that. The "bolts" on those cranks are faked. Rivets usually.
Cheap rear ders are interchangeable, until you get in to racing stuff with 9,10, or 11 cogs, those have very skinny chains, sprockets and cages on the ders.

Cutting the shell out and welding in a new one? Alignment is critical. Put the shell in at any angle and the chain will keep falling off. Even 1 degree off is a problem.

 

[rickpaulos]

Another issue with single speed conversion is how do you adjust for chain length? I don't see any way of moving the axle closer/farther from the bb in the photos. You would probably need a der to take up the slack anyhow. Overall, much easier to just stick with a 5 speed setup. With that big freewheel for 1st gear, the sprocket size should be okay as is.

I'd want to pull the crank just to clean & relube. From the looks, the overall condition suggests all the bearings need cleaning and lubing. Axles, headset, bb, freewheel, etc.

 

[wheelhorseman]

Hey thanks for the info. What scared me is reading about these old sears being Austrian made and cranks arent interchangable. That old 5 speed cassette is working like new BUT I hate that 40t sprocket and short kiddie arms. As for a one speed keeping chain adjusted properly I see these cheap pocket bike tension arm rollers on Ebay. As for keeping the 3 piece crank there is no such thing as a 36t sprocket with long arms. Most single speed trykes are 36/22 and thats really my goal. Lord knows where you could get shifter parts for this dinosaur. I wouldnt even know where to look for a cable.

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[kingfish254]

I bet if you soaked that derailleur it would work just fine. If it doesn't, it shouldn't be hard to find an old 10 speed and use the RD from it.

Same with that shifter.

As far as cabling goes. Regular shifter cable should work just fine.