Better for chain to be too tight or too loose?

[dave_sd]

I just fitted a new chain to one of my bikes and it measured out kind of funny. It's a 7 speed freewheel with a standard crank: big ring is 52T and big cog is 26T, and I used one of SRAM's 8-speed chains (shouldn't matter because 7 and 8 speed chains should be the same width). I've always followed the 2 link rule without a problem, but it didn't work out with this bike...the link that would've connected up before adding the 2 links was about 1/2" short, so I added 4 links instead.

So...is it better to run the bike with a chain that is slightly too short or obviously too long? I read in another thread about a half-link. Is that the fix here?

Thanks,
Dave

[Bill]

I am gonna make a guestimation on this one, so anyone hopefully can confirm or correct me. If I am right each manufacturer has specs that are not let known. Like the ring is rated so many teeth as the cog is rated so many teeth for each model of chain made. Plus you have to put into the equation of the bicycle's geometry, length of chain line, etc. So if the bike has added teeth as well as a longer run from the bottom bracket to the wheel's axle then yes you would probably have to add more links?


Bill

[DaveM]

Too long and the chain will rub on the bottom of the derailleur when you're in the small to small combination. Too short and you can damage (or at least put extra stress) on the derailleur when you're in large-large. Technically you shouldn't be in either of these combos, but it's better to have things set up so nothing bad will happen if you shift into either by mistake. Seems like "too long" has less chance of causing real damage.

[dave_sd]

The chain is definitely too long. It doesn't mesh well with the gears when it shifts. Guess I'll have to consult my LBS again and see if they've ever run into this.

[dave_sd]

An update, I removed 2 links and the chain is too short. It binds in the rear derailleur in the big-big combo.

[cyclerUK]

Dave, What setup do you have?
Chainset rings ?
Cassette speed and range?
Type of rear derailleur.
Have you changed anything else?
Did the old chain work O.K.?
Why are you fitting a new chain?
Do you still have the old chain that you check against for length.

If the new chain has no stiff links and is the correct type then I would be suspecting something else.
Big to Big + 1 link (1 inner & 1 outer) should work fine.
If the chain is to tight then allow another link.

[RobAR]

Dave. Do me a fave?
Forget all of those diagrams and drawings that you have seen in Shimano instructions and elsewhere. In small / small, your rear drlr should be able to take up ALL slack and leave the chain taught. Did I spell that right?
Front and rear drls have Min & Max capacities and if you don't change any gearing, replacing the chain is a breeze.
In small/small, with a good, strong rear drlr, you might see 1/4" of clearance between feeding chain and lower jockey pully. They should NOT make contact.

[dave_sd]

Yup, taught. That's one of those words where if you think about it too long it starts to look a little weird.

The chain on this bike has always been a little funky. It would ride between gears sometimes, and sometimes would skip along the top of the teeth and I'd have to backpedal a little to get it to mesh. I suspect the shifter could maybe do an 8 speed freewheel because it occasionally clicks that many times. All the more reason why I want to get rid of it...it's a little unpredictable.

All the components are Suntour Blaze, and the rear derailleur is probably shot, to be honest. I haven't tried adjusting the b-screw or anything. The front is 52-42, and the rear is 26-23-20-18-16-14-13.

I can play with the rear cable tension and get it to work a little more predictably. The gearing in the back could be worn, too. The bike was built in 89, and I think it's all original components still. The thing is I don't want to dump a bunch of money into it, so I'll try to sell it "as-is", I guess.

[JonB]

What you want is one of these:

http://www.chainreactioncycles.com/Models.aspx?ModelID=17282

You should then be able to run your chain at it's current length, and use this to take up the extra slack. Granted it'll probably look badly out of place on a non-MTB, but it doesn't really matter I don't think.

Or maybe try running a longer cage derallieur?

[dave_sd]

Freewheel was worn out, which allowed the chain to skip around. I.e. my problem had nothing to do with the length of the chain. I love closure

[Bill]

Yup when chainging the chain always look for the "shark" tooth on the freewheel.