Chain length for 11-28 cassette?

[oldgreyandslow]

Can someone please just clarify the method to set the chain length on a 105 set up with a 28 tooth rear please?

I thought you just put the chain on the largest front and rear, without going through the pulleys and that was the length, however for an 11-28 this document http://techdocs.shimano.com/media/t...SI-5X90B-003-00-ENG_v1_m56577569830702204.PDF
seems to suggest doing this and ading 2 links.

Also I guess I need to adjust the B tension screw to get clearance for the pulley at the top end.

Ta

 

[machew]

When I have changed the chain, it was biggest to biggest and add two links

 

[HLaB]

I've always added two links, big to big, no rear derailleur (I think Sheldon and BikeDoctor have instructions on this) but I recently changed to a 11-28 cassette to be doubly sure I also compared it too some chain length calculators and given my lenth of chainstay the rounded result (they reccomend rounding up) was the exact same.

 

[oldgreyandslow]

Thanks folks, big to big plus 2 links it is then.

 

[youngoldbloke]

I use the Machinehead chain length calculator. Might be interesting to see how it compares with the 'hands on' methods.

 

[oldgreyandslow]

The definition of what is aone link in the machinehead calculator seems differnt to the one in the shimano doc here
http://techdocs.shimano.com/media/t...SI-5X90B-003-00-ENG_v1_m56577569830702204.PDF
at least I think it is unles the shimano doc is showing you one link, in which case it is the same and I'm being thick!

 

[Rickshaw Phil]

The definition of what is aone link in the machinehead calculator seems differnt to the one in the shimano doc here
http://techdocs.shimano.com/media/t...SI-5X90B-003-00-ENG_v1_m56577569830702204.PDF
at least I think it is unles the shimano dod is showing you one link, in which case it is the same and I'm being thick!

Was going to post the same thing. What Machinehead call 1 link is what I would call 2 links. My latest chain was purchased as a 114 link one not 57 link.

To be honest, in the time it takes to measure the chain stay then go and put the details into the chain calculator you could use the big to big +2 links method and have the chain fitted.

 

[youngoldbloke]

Doesn't a complete chain link consists of an inner and outer part - 2 inner plates, 2 outer plates, and 2 rollers form one link, you can't shorten the chain without removing the inner/outer unit, though you can replace the outer part with a quicklink.

To be honest, in the time it takes to measure the chain stay then go and put the details into the chain calculator you could use the big to big +2 links method and have the chain fitted.

I find it quicker

 

[Rickshaw Phil]

Doesn't a complete chain link consists of an inner and outer part - 2 inner plates, 2 outer plates, and 2 rollers form one link, you can't shorten the chain without removing the inner/outer unit, though you can replace the outer part with a quicklink.

That is how Machinehead are defining 1 link but Shimano, KMC, et al are defining it as 1 pair inner or outer plates + roller, hence 114 links in a new chain. If you do the big to big +2 links method as 2 pairs of inner plates and 2 pairs of outers you'll end up with a chain that is too long.

I find it quicker

If it works for you then no problem.

 

[youngoldbloke]

Yes - can see that. Point is if you use the Shimano definition you can't add just 1 link, it has to be 2. You can't have an odd number of individual links in a chain, but you can have an odd number of pairs.

 

[Rickshaw Phil]

Yes - can see that. Point is if you use the Shimano definition you can't add just 1 link, it has to be 2. You can't have an odd number of individual links in a chain, but you can have an odd number of pairs.

Sorry if i'm being stupid but I don't see why that is an issue.

There is always the possibility that when you measure out the new chain the join will be to matching plates (inner to inner or outer to outer) in which case you'd need to add 1 extra (Shimano definition) link to make it join.

 

[youngoldbloke]

Sorry if i'm being stupid but I don't see why that is an issue.

There is always the possibility that when you measure out the new chain the join will be to matching plates (inner to inner or outer to outer) in which case you'd need to add 1 extra (Shimano definition) link to make it join.

No issue, no problem - as long as you realise what you're doing - my point is that if 1 link = inner+outer you won't end up with matching plates. I always have to think hard when I am adding a quicklink, when you want to end up with inner plates .

 

[GrasB]

big to big + 2 links is the minimum chain length. However on my non-race day bikes I've taken to marking the minimum chain length & then adding as many links as possible while still maintaining tension on the chain in little to little. The reason is it leaves a little more scope for correcting chain problems mid-ride. While losing a link or two won't end your ride an accidental shift into big to big with a two short chain will almost always lead to a ride ending mechanical!