Bicycle Mechanics - Chain legnth can you be off a couple of links?

Does it have to be exact or can you be off a couple of links. I had an old chain and my friend would break off a few links (maybe 3 or four) to get the pin since he lost his pins. If i reinstall the chain on the bike it came off of can it still be used? there's maybe 3 or four links less than before. Does it have to be exact?

The bigger issue is resusing pins. That is a good way to crash your bike from the resulting weak and soon to be broken chain. Pins aren't that expensive and neither are most chains.

BUT... if it doesn't bind in the gear combinations you use you're good.

I think you're missing the fact that it's nearly impossible to reuse pins once it has been pushed out. Seriously not worth the trouble.

IF you cross chain to BiG-BiG, it might REALLY bind things up bad.
Some bikes come from the factory with overly long chains, so maybe????

Yes you can. As far as my experience goes, you can go add two links or subtract two links (4 half links) and still be fine and shiftable. However, optimal smoothness in shifting usually is best at a certain number. Also, there is less leeway in road bikes for some reason.

As for the problem of the pin, go buy a Wipperman Connex or buy new master pins. Reusing an old pin is not safe and will pop out in the worst conditions, like when you shift or when you stand up and pedal. Experienced riders can get away with a foot slip and it will be a face plant for non experienced riders. And don't forget the loss of the RD.

Your chain needs to be long enough to safely cover the big/big combination even though you may never shift into the big/big.

Some nice day, when everything is going good, you'll come to a little hill and decide to sprint the hill in the big ring. As you slow near the top of the hill you downshift shift one more time. SURPRISE! Your too short chain has just caused your rear derailleur to bend into the spokes. You've just ruined your rear derailleur, your rear wheel and maybe caused serious damage to your frame too. As you start the long walk back to your car you think to yourself that it's not such a nice day anymore.

In most cases, removing a couple of chain links from your bike isn't smart.

Your chain needs to be long enough to safely cover the big/big combination even though you may never shift into the big/big.

Some nice day, when everything is going good, you'll come to a little hill and decide to sprint the hill in the big ring. As you slow near the top of the hill you downshift shift one more time. SURPRISE! Your too short chain has just caused your rear derailleur to bend into the spokes. You've just ruined your rear derailleur, your rear wheel and maybe caused serious damage to your frame too. As you start the long walk back to your car you think to yourself that it's not such a nice day anymore.

In most cases, removing a couple of chain links from your bike isn't smart.

+1

Walmart sells chains for cheap...there really is no need to try and hack apart an old chain and piece it back together with used pins. Dangerous and in the end will cost you much more money when it blows apart your RD.

not a good idea. I re-used a chain after taking out several links to try out a single speed, it lasted for about a month before the pin came out. I wondered how long it would take. So I purposely didn't sprint or get on the pedals to hard.

Your chain needs to be long enough to safely cover the big/big combination even though you may never shift into the big/big.

What he said.