Quick question on chain length after changing from Compact to Road crank

moby2101

Hi lads,

I've just changed the crank from 50/34 to 53/39, am I right in thinking that the chain is fine as it is, doesn't need to be made longer!?

Thanks,

Mike

Idleater

Assuming nothing else has changed then it may need an extra link or two.
Put it onto the big ring on front and back and see how the rear derailleur looks.

moby2101

Ok will do, thanks for that

Lumen

Technically you might need 0.82 links more, but I wouldn't bother splitting or replacing a chain for that.

53 links works for most combinations.

moby2101

Hi lumen,
How did you work out that calculation? I hear your pretty renowned for graphs & stats.

Lumen

moby2101 wrote: »

Hi lumen,
How did you work out that calculation? I hear your pretty renowned for graphs & stats.

Spreadsheet attached.

edit: can't remember where I got the equations from. Maybe Sheldon or here:

http://www.parktool.com/blog/repair-help/chain-length-sizing

Hi OP. I did the same on one of my bikes. It was fine, no need to add extra links to the chain. As Lumen mentioned, the theoretically required increase in chain length is quite small. In practice it's unlikely that there wouldn't be enough spare chain to start with. Just put it in the big/big combo and see if the rear derallieur can cope ok.

moby2101

Cheers lads, happy St pattys day! Ill be out in the morning on me crank, looking for loads more speed!