[KobayashiMaru]

Bought a bike with a 30 tooth 1x crank. Setting it up for me with a 2x crank and the big ring is a 34 tooth. Using the length formula (2 times chainstay length, plus big ring divided by 4, plus big cog divided by 4, plus 1) I need 54 links and the brand new chain the bike came with has 53 links.

I know people shouldn't ever cross chain and do big/big, but I will admit I've looked down before after some super hard sprints and seen myself one or two cogs away from doing it because I only down shifted the rear derailleur and forgot to shift off the big ring.

Would one link too short make my drivetrain explode if I stupidly put it in big/big?

 

[J.B. Weld]

Just to avoid confusion I think it's best to use the right terminology when referring to a chain link. New chains are usually 116 or 126 links and all the directions I've seen use that standard when sizing them.

So, you can only add or subtract 2 links at a time and ime sometimes 2 links short of correct can be a problem and sometimes not. When in doubt I always error on a little too long.

 

[KobayashiMaru]

Yes, that has always bugged me. One inner and one outer makes up one link, which equals one inch of chain, but that just seems so strange to me. "One link" seems like it should be one section between two adjacent pins, but I see the terminology both ways in different sources. I pick one and hope people know what I'm talking about.

So yes, by the formula, the chain on the bike is an inch shorter (one inner piece and one outer piece) than would be ideal. One inch is a lot. Makes me think I should add enough to it just to know it's ideal, but has anyone run a chain one inner and one outer too short and been ok? I'm assuming everyone would be ok until the big/big.

I know if the bike can make the shift it should be ok, so I should just hook it all up and see if it can make the shift and see how much wiggle there is, but I'd feel way more warm and fuzzy if some people that have done that very thing tell me it worked out ok for them.

I just really want to be lazy here and not add the links.

 

[fmendes]

Would one link too short make my drivetrain explode if I stupidly put it in big/big?

You didn't mention if it's a HT or FS. If it's a HT and the big/big works on the stand, will likely work at the trail. If it's a FS and things are tight on the stand, will likely explode on the trail.

 

[KobayashiMaru]

You didn't mention if it's a HT or FS.

It's a full suspension. Just 80mm of travel, but still.

I remember letting all the air out of a 120mm shock on another full suspension bike I had to wrap the chain on big/big for fit and the links required weren't any different than the links that the formula gave me, so I'm still thinking I'd be ok.

Truth is, I could have scrounged up another masterlink and added the extra bits by now with all the time I've spent typing.

 

[eshew]

Try it out, get the rings installed and run the bike through it's gears, go SLOWLY into the big big. Ideally in a bike stand. If the chain is too short it will refuse to go and bind, if not it'll work fine. Running 2 master links isn't ideal but it's not a deal breaker either.

If it works with the standard length chain remove the rear shock and cycle the suspension while it's in big/big, if the derailleur cage still has room to swing forward throughout the travel range you should be good to go.

If you do go with the extra link/ double master link make sure to check for chain sag in small small. Don't want that chain just hangin around all slack.

 

[KobayashiMaru]

Mounted the cranks. It wouldn't shift into the biggest cog on the cassette with the chain on the big ring. I shoved the shifter as much as I could past the index point to try and make it move, but it wouldn't do it. It shifted onto the big cog with the chain on the small ring, so it's not a derailleur adjustment issue.

I'm guessing I don't have to worry about it? I can't make it get on that cog, so I'm thinking it won't get on that cog. The noise from the cross chaining on the next to biggest cog is loud enough to alert me I'm cross chained if I ever do it, so I don't think I ever would.

It's got 53 (106) links on the chain. If I change the big cog from 36 to 32 in the equation, then the chain that's on it is fine.

 

[eshew]

I'd try and add another quick link and a few more links just to try and get it working correctly. Even if you cant physically get it into that big ring in back. I'd be worried about some freak occurrence, what happens if that chain grabs a tooth on the big ring. That's potentially a lot of force and could lead to an expensive repair bill.

 

[KobayashiMaru]

Ugh......

You have my worst case scenario radar sounding alarms.

I guess I'll make two new cuts halfway around the chain away from the current quick link to take out 4 or 5 (8 or 10) links and add back the same number plus one from leftovers from another new chain. Two new cuts and a total of 3 in the whole chain. Same numbers with quick links.

Yes, it's maximum jank, but I get every penny I can out of everything. No sense in not using a brand new chain.