Stupid chain question

[B4_Ford]

When swapping from a 50/34 crankset to a 53/39, is it necessary to replace the chain? My abundance of caution leads me to believe it’s necessary, but is it really?

[joevers]

Yeah extremely likely needed, unless you're nowhere near your derailleur capacity and chain is on the long side.

[kppolich]

Probably, but you won't know for sure until you install it.
Same cassette or are you changing that too?
Install the new crankset and check the B-limit on the RD and angle on the RD cage up and down the cassette, you'll see if it's over stretched or not right away.

[B4_Ford]

Originally Posted by kppolich

Probably, but you won't know for sure until you install it.
Same cassette or are you changing that too?
Install the new crankset and check the B-limit on the RD and angle on the RD cage up and down the cassette, you'll see if it's over stretched or not right away.

Cassette will remain 10 speed 11-28.

[indy.cyclist]

While the sage has guided well on what one should should do, I will speculate and say you will be ok with the current chain - unless It is already so tight that the RD is pulling taut when you are in 50x28.

I use this calculator and it seems to be a good approximator of how many links I need to remove. I am almost never adding.

http://www.machinehead-software.co.u...engthcalc.html

[Mark McM]

Originally Posted by indy.cyclist

While the sage has guided well on what one should should do, I will speculate and say you will be ok with the current chain - unless It is already so tight that the RD is pulling taut when you are in 50x28.

This is the correct answer. Remember, the chain only wraps around half the chainring, so the maximum extra chain required when switching for a 50 to 53 chainring would be 1 1/2 links. Chains can only be sized in 2 link increments, so there's a very good chance that the chain length required for a 50 and 53 would be the same anyway.

[Dave]

Use the simple calculation method, if your chain stay length is accurately known. See park tool website. Otherwise use the big/big plus one inch method.

My setup exceeds my RD wrap capacity, so it's deliberately a little long. I already know that I can change from a 46 to a 48 big ring with no problem.

[oldpotatoe]

Originally Posted by Mark McM

This is the correct answer. Remember, the chain only wraps around half the chainring, so the maximum extra chain required when switching for a 50 to 53 chainring would be 1 1/2 links. Chains can only be sized in 2 link increments, so there's a very good chance that the chain length required for a 50 and 53 would be the same anyway.

That's correct except he is going from a 34 to a 39..so I expect that he'll need a longer chain..IF the chain was of a proper length to start with.

When installing a 'compact, 50/34 on an otherwise 53/39 'system..generally 1 or 2 links out..

[Mark McM]

Originally Posted by oldpotatoe

When installing a 'compact, 50/34 on an otherwise 53/39 'system..generally 1 or 2 links out..

How do you take 1 link out (and still be able to re-join the chain)?

[dddd]

I always check for minimum needed chain length using very quick quantitative eyeball measurement.

All one has to do is to carefully put the chain in the big-big sprocket combo, squat down by the right crankarm and position the pedal at 3:00.
Then use right hand to hold the pedal downward solidly while grasping and pulling the front of the lower chain run forward so as to slip past as many chainring teeth as possible. You will need to see the chain roller move at least 1-1/2 teeth past the tooth that it WAS resting against, which is the measure of chain slack.
Two full teeth is the usual recommended minimum, but sometimes (with perhaps wider gearing and only a short-cage derailer), I will fudge that to as little as 1-1/2 links/teeth of slack IF the chain is new when I do this measurement.
Keep in mind that when installing a new chain that things will be tighter than with a used chain, which is why two full links can be a better conservative minimum than 1-1/2 links.

Sufficient chain slack is needed to allow for worst-case situation of partial derailment over both the front and rear biggest sprockets simultaneously, which will happen sooner or later. Any less and the chain tension can peak at values that can damage frame, cassette, crankset, chain and rear hub.
But no worries with the derailer itself, since most rear derailers will pivot freely out of the way of a too-taut chain.

[Duvivr6]

Originally Posted by Mark McM

How do you take 1 link out (and still be able to re-join the chain)?

Sounds like a trick question 😂

[m_sasso]

Originally Posted by Mark McM

How do you take 1 link out (and still be able to re-join the chain)?

Originally Posted by Duvivr6

Sounds like a trick question ������

3/32 half master link

[oldpotatoe]

Originally Posted by Mark McM

How do you take 1 link out (and still be able to re-join the chain)?

Huh?..Either take what you need leaving 2 inside portions and use a quick link.

Or on a new chain, size it..use a pin and proper tool(if Campagnolo)..

[LeMond123]

I would carefully try it first as others suggest. I sized mine big/big and was having just terrible sloppy shifting for a ride or two. Begrudgingly took out that last couple links, and shifted fine ever since, even big/big on the stand (would never purposefully do that of course)... so I either messed something up or...?

[Mark McM]

Originally Posted by oldpotatoe

Huh?..Either take what you need leaving 2 inside portions and use a quick link.

Or on a new chain, size it..use a pin and proper tool(if Campagnolo)..

But other than with the use of a "half-link" (referenced above), you can't shorten or lengthen a chain by 1 link increments. You have to remove/add 2 links a time - one link with outer plates, and one link with inner plates.

Since the chain engages with only half the teeth on a chainring (or sprocket) at a time, it takes a 4 tooth difference in chainring size to match a 2 link difference in chain length. So you can't really make a chain length adjustment for a 1 or 2 tooth difference in chainring size, and there's only a 50% chance that a chain length adjustment can be made for a 3 tooth difference in chainring size.