Tight chain - can it cause damage?

[Davidc]

I changed the chain on my wife's bike this afternoon.

Owing to a counting error (entirely my fault) it's very tight.

It will go into big ring - big sprocket, but only just.

if it was on mine I wouldn't worry as that combination would never get selected but on that bike it may do. Is it likely to do anything nasty if it does?

 

[Brommyboy]

A mis-change to the largest sprocket/chain ring could easily break the chain!! Put some extra links in! When chain is around largest ring and sprocket, put in two extra links if only single/double chainring, four if a triple.

 

[RecordAceFromNew]

In the meantime you can adjust either or both mechs' limit stops to stop the chain going on either or both large rings.

 

[Davidc]

The SRAM instructions say measure it around large/ large and put in either 1 or 2 more links to give 2 inner plates to meet the powerlink. I've ended up with 0 + powerlink.

(I normally count the links twice on the old chain then twice on the new one, this time I didn't so my fault!)

Trouble is that to put 2 links in without getting silly means pushing out a rivet then pushing it back in. I have the offcut piece of chain so could do it, and would if it was a Shimano chain, never having had a problem doing so, but I've never tried that with a SRAM chain. It's a PC850 chain.

So what chance a success re-riveting one of these? I rode the bike half a mile to try it and although it works it really is too tight.

How long before the chain 'stretches' enough for a comfortable margin to be restored? Is it ever going to be put in the large/ large combination?

I've never done this before.

 

[RecordAceFromNew]

Regarding the chain length imho following a chain calculator is best. Could you try it and see whether it is right according to the calculator?

Further if the rear mech has enough "wrap capacity" using a chain somewhat longer than the theoretical "optimum" has no meaningful negative effect (well a couple of grams heavy...). If you can provide the chainset, cassette and rear mech specs, I am happy to work out how much longer you can use for you.

 

[RecordAceFromNew]

Regarding riveting, PC850 is an 8 speed (works for 5 to 8 speeds) chain so not as "tricky" as a narrower chain. I don't see why it is going to be harder than a Shimano chain to work with.

As you probably know the trick is not to push the pin completely out of the face plate while being able to extract/insert links, so patience and going little by little and checking every couple of turns of the chain tool helps. When reinserting on the plate at the other end careful lining up and not forcing it while and if unaligned is key.

This might help.

 

[Davidc]

Regarding the chain length imho following a chain calculator is best. Could you try it and see whether it is right according to the calculator?

Further if the rear mech has enough "wrap capacity" using a chain somewhat longer than the theoretical "optimum" has no meaningful negative effect (well a couple of grams heavy...). If you can provide the chainset, cassette and rear mech specs, I am happy to work out how much longer you can use for you.

That's not a problem - the system works fine with the number of links it had - it's just that Mr Idiot here cut it a link short. Because that can't work I had to take another out to get the powerlink in. If I'd been paying attention I'd have realised that I had an outer and an inner pair of plates instead of 2 inners for the link; before I cut the chain.

The end result is that the silly gear combination of 2 x big gives a very tight chain with the rear mech at a silly angle.

The only real solution is to put 2 links back in. My only reservation is whether the SRAM chain is as amenable to surgery as Shimano ones have been. Doing it isn't the problem, it's whether or not the chain will tolerate it.

The reason I've done the surgery on Shimano HG chains is that I've never succeeded in getting a Shimano joining link to go on, so I just rivet them, whereas the powerlinks are a doddle to make work, and until they've been in use for about 250 miles get off again.

The ultimate issue is that I don't fancy the fully justified flack if that chain falls apart while it's being ridden either because of being too short or becaause the plates come apart at the join - I feel physical pain coming on in my more tender parts .......

Regarding riveting, PC850 is an 8 speed (works for 5 to 8 speeds) chain so not as "tricky" as a narrower chain. I don't see why it is going to be harder than a Shimano chain to work with.

It probably isn't - I've just not needed to do it. This bikes a 7 speed - an ageing Raleigh MTB - and works fine with cheap Shimano and SRAM chains.

 

[2Loose]

Could you easily get and fit another powerlink? It would be a solid and easy way to do this...but only if you can get hold of another powerlink easily.

 

[John the Monkey]

I've done this too, on the first replacement chain I put on the tourer.

I popped out enough links to make room, and lengthened the chain with two powerlinks - it worked fine.

 

[Rob3rt]

In future, I find a good way to get your chain the right length is to hang both chains side by side from a nail in a block of wood (or other suitable jig - in my case, pinning them to the kitchen wall) and then using common sense with regards to the old chains "stretch" to determine where to break the new chain, I find counting links to be error prone, needing several counts to ensure there hasnt been a mistake, it takes too much time and its boring visual inspection is quick, reliable and repeatable

The SRAM chain should be absolutelly fine for you to do a bit of surgery on putting in a few more links or even just break it and put a couple of power links in. I use SRAM chains on my fixed and dont use the power link, I just break and rejoin the chain and I've never had a problem. Just make sure that after joining the chain, that the link moves freely.

 

[fossyant]

Either save the chain for another bike, and get a new one - might be less agro. Put back in a couple of links (if you still have the pin (8 speed chains generally are OK for this - I wouldn't with a 9 plus chain), or add another power link and bit of chain.

If large x large did get selected, then you don't want it jamming, hitting the spokes, smashing a wheel, mech and drop out - oh and getting kicked in the goolies from your partner !

I'd just get a new chain, and use the other on another bike.

 

[Davidc]

Thanks for the comments. After reading them I've spliced in 2 links (from the bit I cut off) and it seems to be fine, with free movement and back to the length it should have been in the first place!

I did think of using another chain Fossy, but as this bike has the equal shortest of the 4 bikes here re-use would be a non-starter.

A naughty thought did occur to me - If I kept all the offcut bits of chain for a couple of years I could join them all together and make another chain from them - free! Don't think I'll try it somehow.

 

[oldroadman]

Bear in mind that chains do not "stretch", this is WEAR in the pivots of the pins, the whole thing is very slowly grinding itself away. Which is one good reason to keep 'em clean and well lubed.
Other point, the mechanical disadvantage of having a chain too "tight" means that whilst deflection (i.e. big ring, big sprocket) is the same, the movement will require some extra wattage to overcome more mechanical disadvantage than there should be (and that's enough). Ideally, no bike with an 8 speed cluster is 16 speed, the sensible and usable ratios on a traditional spaced cluster will mean using 10 or 12 at the maximum. Why would you use, say a 53 ring with a 22 sprocket, when 39 x 16 will give you a close enough match, and put less pressure on the chain, less mechanical stress from literally"bending" the chain, thus slightly less effort for the same speed esult. All explained to me many years ago by one of the world's best team mechanics, and he and his colleagues had to change the chains on the team bikes every two/three weeks anyway so knew a thing or two about 'em.