I'm trying to fix my wife's bike. It's been sitting outside and the chain is rusted. The bike is a 2010 Trek Pure low step. It’s a 7 speed with a KMC chain that has the numbers 3 and 70 and narrow on the other side. According to the Trek site, it’s a “KMC Z51 7” but I can’t find a 136 link version. Does anyone know where I can find a decent replacement that isn’t too expensive?
Thanks in advance and any help would be greatly appreciated.
by agms10
7 Comments
Have you tried buying directly from KMC? That’s where I’ve always sourced my chains when it wasn’t from my LBS.
You definitely don’t need 136 links
Chainstays have become shorter over the years so chains don’t come with as many links. Look for an ebike chain, there’s plenty of 7 speed 136 link available
KMC offer good value, but apparently there are a lot of fakes out there. I buy from places I know and don’t think I’ve been bitten, but do pay a little bit more than some of the ‘bargains’ on eBay or wherever for peace of mind.
You may need to buy a couple of chains and join them to get that length. Using a couple of Quicklinks shouldn’t be an issue.
Surface rust from sitting outside doesn’t warrant replacing in my opinion, you can clean it up easily and it’s won’t affect anything.
If the chain has no wear (you’ll need a chain wear indicator to figure that out), I say clean it up, oil it properly and keep it
Go to a bike shop and get whatever $20 7 speed chain they have. Which is likely a KMC.
You don’t need this specific model. Just look for any 6/7/8 speed chain with 136-138-140 or even more links. KMC, Shimano, Sram, YBN are fine (not talking about fakes, because that’s whole another can of worms).