Rule of thumb for chainlength when increasing chainring size

Triathlon Forum
1

Thinking about going to a 53 tooth standard setup instead of the 51 that I have at the moment. If I do this, is there a rule of thumb regarding how many links to add to my chain? I know how to determine chainlength by looking but was wondering if there was simply a standard rule when increasing or decreasing chainring sizes.

Thanks.

2

Sram says “big big and add 1 inner & 1 outer link” so going with that I would add 1 inner & 1 outer link for the 2 teeth you gain
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3

Great. Thanks.

4

Just make sure that you have enough chain to go big big without everything going SUPER tight. I’ve seen the damage first hand on what can happen when chain is too short. Completely ruined frameset.

5

formula for chain length
L=2(C)+(F/4+R/4+1)
L=Lenght of chain
C=chainstay length in inches (to nearest 1/8)
F=largest chainring teeth
R=largest cassette cog teeth
so you would be adding 1/2". links are 1". Look at current length and either leave as is or go up one link.

6

I would never add links to a chain, for $30 I would buy a new one.

jaretj

7

formula for chain length
L=2(C)+(F/4+R/4+1)
L=Lenght of chain
C=chainstay length in inches (to nearest 1/8)
F=largest chainring teeth
R=largest cassette cog teeth
so you would be adding 1/2". links are 1". Look at current length and either leave as is or go up one link.

Nice. Thanks for this.

The chain is new last week so I don’t really want to have to fork out for a new one. It’s a Sram 1070, so it cost $65 here.

8

Then I suppose it makes sense to add a pair of links if you need them.

jaretj

9

Brand new chain? Did you remove many links when you put it on? I bet it’s more likely than not that it is fine as is. And, ask yourself if you have ever used the biggest front and back rings at the same time (extreme cross chain), if not then you even more likely to be okay. David K.

10

Thanks for that. I don’t usually use the big/big combo but I don’t want to chance destroying stuff if I try and change to it. I did shorten the chain when I installed it. It is a good length at the moment. It may even be OK when/if I put the larger chainring on. I can always put it on then test and see.

11

Unless your chain was too short to begin with you should be fine. A buddy of mine switched to a standard crankset from a compact one and had no issues. Several rules of thumb have been offered up, none of which indicate a drastic change. Try it first because it may very well work without any tampering, then add if needed.

12

Sram says “big big and add 1 inner & 1 outer link” so going with that I would add 1 inner & 1 outer link for the 2 teeth you gain

formula for chain length
L=2(C)+(F/4+R/4+1)
L=Lenght of chain
C=chainstay length in inches (to nearest 1/8)
F=largest chainring teeth
R=largest cassette cog teeth
so you would be adding 1/2". links are 1". Look at current length and either leave as is or go up one link.

Just add half a link then.

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#wiseass

13

Put on the 53 and see if it changes to big/big without feeling REAL tight.

In the olden days that what’s we did. If the rear DR cage was horizontal then we knew to add a link or two. Then checked to make sure we could pedal without skipping in small/small.

At one point I had a triple and in order to get the small chain ring to shift well on the few gears I used it on (about half the rear sprocket), I set it up so that I could not go big/big, the chain was too short. Plus I didn’t want to cross chain. And this was on about a 7 speed rear cluster. The beauty of this was that I had a bailout gear of about 31/36 for climbing European goat trails with 70 pounds of gear on the bike. But with a 53/12 could motor down faster than the cars.