Chain length

chichee

How do you know if the chain on your bike is too long? Or alternatively, too short? Would it more rigid and stiff in certain gears? Or loose in other gears?

supersonic

There is an item on chain length in the FAQ.

If too short, then in the big ring/big sprocket combo you will damage parts.

If too long in the small/small combos the chain will sag. (though this can be due to the wrong cage length of the derailer too. However you shouldn't use these gears).

chichee

I've taken pictures to show you what I mean.

The first picture shows the big ring/big sprocket combination.

3x8 by mrhau, on Flickr

The second photo shows big ring/small sprocket.

1x8 by mrhau, on Flickr

And finally, the last picture shows small ring/small sprocket.

1x2 by mrhau, on Flickr

I think judging by the last picture, there is too much sag and the chain is definitely too long. Can anybody confirm or give their opinion.

Thank you in advance!

leaflite

Looks too long to me

kinmofo

in the small / small gears, make sure top is tentioned, and "pinch" the chain at the bottom, this will show you roughly how many links to remove.

personally i dont use the big ring, or the medium. i have small and V small lol. took big and medium ring off, obv i had to shorten my chain, like i just said, on the small / small gears u pinch the bottom, say its 3 and a half links, remove 4.

this is what i do, and i haven't had any problems.

supersonic

To measure the chain length, see FAQ. It should be done as in there as to prevent damage if you hit the large/large combo.

on the small / small gears u pinch the bottom, say its 3 and a half links, remove 4.

This is potentially dangerous for the above reasons.

chichee

Do you mean this thread? http://www.bikeradar.com/forums/viewtop ... t=12687774

chichee

I've searched on the forum and found links to the Park Tool website where they have explained how to correct the chain length.

http://www.parktool.com/blog/repair-hel ... gth-sizing

I think the easiest and most logical way is to follow this method - Chain Sizing - Largest Cog and Largest Chainring Method.

supersonic

Yes, this is correct ie large - large method.

mattv

SRAM setups often look like that. Sometimes you can take 2 links out and its better. Also check the b-tension screw is set correctly.

cooldad

Taking random links out is stupid when you can just measure it properly.

chichee

I have had a go at shortening the chain and managed to work out that it was 2 links too long (2 complete links - male/female). Not sure whether that is correct or not but will take pictures for you guys to pass your judgement over.

I did, however, try to shorten it by 2 more (complete) links but it was too tight and I wasn't able to join up the chain. Actually I gave up because it was starting to annoy me! :evil:

supersonic

When you rejoin it, make sure the gears are in the smallest cogs - or even derail it off the front onto the bottom bracket shell to give you more slack.

chichee

I rejoined the chain in the small/small ring/cogs, left the rear derailleur/derailleur pulley all tucked in under the cassette and there was still a little slack from the chain - is this correct? Or, should I have had some tension on the chain? Meaning the rear derailleur/derailleur pulley will start to extend out.

davewalsh

Looks to me like it's a short cage rear mech. You'll never get the chain length right when trying to run this mech with a triple chainset. You need a long cage mech to take up the extra slack.

What's the distance between the centres of the jockey wheels ?

chichee

davewalsh wrote:

Looks to me like it's a short cage rear mech. You'll never get the chain length right when trying to run this mech with a triple chainset. You need a long cage mech to take up the extra slack.

What's the distance between the centres of the jockey wheels ?

Are you referring to the pictures in the posts further up?

davewalsh

Yes.

Compare the cage length to Inbred 1 in my signature and you'll see what I mean.

chichee

davewalsh wrote:

Yes.

Compare the cage length to Inbred 1 in my signature and you'll see what I mean.

It is a noticeable difference. Is it possible to just buy a cage of different length and replace? Or, is it a difficult thing to do?

supersonic

You din't need to use the gears where this slack is occuring.

Slow Loris

The top pulley looks too close to the sprocket to me. Is the mech definitely set back past the 'notch' on the hanger? Failing that is there a b tension screw you can tighten which would increase the chain tension?