bamboo63

I know there's a tandem forum but I thought I would start here since it's an old classic. Anyway, this issue may be common to many old bikes. I'm taking my 9-year-old to school on this purple beast but lately, the chain is coming off in the rear almost daily. I'm guessing you're going to tell me to get a new chain-- or better yet, replace both chains. Just want to hear some advice as I've been out of cycling for a while. Do enjoy our two-speed Twinn and want to keep riding it! Also, would these chains be easy to find, or am I looking at a specialty item?

geo

Peruano

Two chains hooked together make one long chain and usually with a piece left over.

bboy314

Check the same things you’d check on a single bike with this issue - chain/freewheel wear, shift adjustment, derailleur limit screws. Does it come off while pedaling, while shifting? To the inside or outside?

If it needs a new chain, it should be a standard 6 speed (or however many to match your freewheel or cassette speeds) chain.

bamboo63

I should have mentioned: no derailleur. It slips while pedaling, usually when we are pushing a little harder. Slips off to the outside. Given that, how do I select a new chain?

Pompiere

A two-speed will use a different chain than a derailleur equipped bike. Look for a 1/8 inch wide chain, that is the size for single/three speed bikes. Chains for derailleur bikes will be 3/32 inch. All of them are 1/2 inch long from pin to pin. You can check if the chain is worn out by measuring 12 inches of chain, from pin to pin. If the pin at the 12 inch point is past the mark on the ruler, the chain is worn out. You also need to look at the sprockets, since they wear along with the chain. If they look more like shark fins and less like uniform peaks and valleys, they are also worn. If you share your location, someone may be able to point you toward a bike shop or co-op that can help you out.