What length chain to buy?

reaperactual

I've removed my current chain and counted 107/108 links? Started at the inner and finished at the inner link that joins together with the missing link.

So currently run a 30t chainring and 11-42 cassette. My replacements are 32t chainring and 11-46 cassette and don't know what minimum length chain to buy?

I've seen a good deal on a 112 link chain and like a bargain but don't know if this is enough to cover the bigger cog and chainring sizes. Any help is appreciated. Thanks!

brundonbianchi

reaperactual said:

I've removed my current chain and counted 107/108 links? Started at the inner and finished at the inner link that joins together with the missing link.

So currently run a 30t chainring and 11-42 cassette. My replacements are 32t chainring and 11-46 cassette and don't know what minimum length chain to buy?

I've seen a good deal on a 112 link chain and like a bargain but don't know if this is enough to cover the bigger cog and chainring sizes. Any help is appreciated. Thanks!

If it was me, I’d get a 120 link chain, it’s easier to shorten a chain that’s too long, than increase the length of one that’s too short.

reaperactual

Thanks for the reply, Lol! 🤣 Absolutely the common sense answer I expected and a fair point @brundonbianchi. Yes definitely don't want to be adding links.

I've seen a Sram PC1110, 120 link chain on C.R.C. on sale for £21 and 112 link PC1130 chains for around £12 and assume it's a bit better quality? Any opinion, thoughts on that?

Usually go for KMC X type so not sure about Sram chain's reputation overall?

Your probably right and maybe I should go for 120 links then make a bracelet/necklace with the excess! 🤔😀

steve_sordy

Get the longer one and shorten it as required, using any one of the half dozen or so methods.
If you ride a full suss, remember to check the chain length under full compression because on some suspension designs, the rear wheel moves away from the bike when compressing.

Keep the excess chain for when you damage the chain on a ride and have to replace a section.

reaperactual

Hi Steve, thanks!👍 I'm slowly being convinced not to chance saving a few quid on a chain purchase.

Got a nice little chain splitter in my emergency trail kit, the 'Park Tool Mini Chain Brute' that I've only used a few times so far so it'll be used again.

It's for my hardtail so not so complex to get length right.

Just started to wonder if there was some simple formula I don't know about to accurately work out links for increased chainring/cog sizes.

No harm in having a few spare links left over I suppose. Thanks for the advise as always. 😎👌

wilberforce

Alpine trek have a calculator https://www.alpinetrek.co.uk/chain-length-calculator/
Cannot vouch for accuracy I am afraid

wilberforce

Forget the calculator. Looks like it only goes up to 35t sprocket

reaperactual

wilberforce said:

Forget the calculator. Looks like it only goes up to 35t sprocket

Lol!🤣 @wilberforce found out it only went to 35t a few hours ago. Yeah not sure I'd trust it either way. Thanks for giving it a try, appreciate it.😎👍

N0bodyOfTheGoat

I've used http://www.machinehead-software.co.uk/bike/chain_length/chainlengthcalc.html in the past with decent results on road bike and fatbike.

reaperactual

Wow. Had a quick glance and it looks it's written in Chinese to me at first!

I'll take a closer look and see what result it throws up, thanks for the reply. 👍

steve_sordy

I would assume that it is half the number of extra teeth you are adding, because the chain does not go all the way around the gears.

Therefore ((32-30)+(46-42))/2 = (2+4)/2 = 3

it is difficult to add 3 links, so add 4.

So that would make a 108+4 = 112 link chain. So you could get the one you are looking at.

You can buy 120 and that is only 8 more links, or 4" of chain.

Get the 120 and have some spares.

reaperactual

Thanks for the last two posts. So I did check out the link and entered my current and proposed changes to drivetrain @NObodyOfTheGoat.

@steve_sordy you gave me a test figure and (excusing my average G.C.S.E. grade maths) it all seems to back each other up.

Different numbers to how one full link is termed so I've doubled the numbers. Please feel free to correct me if I'm wrong but think it still comes out to the same conclusion and the maths add up to the same with both suggestions?🤔





Coinsidently I've seen a chain for £12 which is 114 links and going off the info I'm pretty confident in buying this one and it not being too close for comfort on the minimum length I'll need and enough spares left over.