broken chain

[Jim77]

i broke my chain today. bloke in the shop said it was prob down to poor gear changing. i had notice it making a bad straining noise as i changed while climbing. what am i doing wrong?

also the chain is shorter now as it had to have a link removed. should i get a new chain or can you have new bits added in?

thanks in advance.

 

[RedBike]

Changing down several gears while pedalling hard (for instance a sudden steep incline) puts the chain under huge force. If there's any week spots they will fail.

Add in weeks worth of off-road / high wear conditions and you can see why snapped chains on MTBs are actually pretty common. If you do any MTB merida there's always some poor sole beside the trail with a snapped chain.

Nobody can say your chain will fail again but it is more like likely to fail again than a new chain. There's no need to put a new chain on. However, you should buy youself a KMC or Sram power link (only about £1/£2) and make sure your multi-tool has a chain tool on it. This way if disaster does strike you can repair your chain sufficiently to get you home.

A shoter chain might not be long enough to reach around all the gears (big/big) but as you should never use this ratio anyway there shouldn't be too much of a problem.

 

[Jim77]

Cheers. Thanks for the advice.

 

[24HourDog]

If it has broken once I would definitely replace it. A little preemptive gear changing will save the legs & your drive train

 

[Cubist]

+1 for the preemptive gear-changing, but you also need to practise. The trick is to get enough momentum up in the first place, and slacken off your pedalling power just fractionally as your thumb hits the shifter. That sounds easy, but takes a bit of getting used to.

Get yourself a chain-splitter and a couple of SRAM powerlinks to keep in your pocket/hydropack/whatever. A tenner's worth of peace of mind.

 

[Black Sheep]

as people have already said, a quick hard stomp on the pedals, ease off while it changes and then carry on up the hill

that or man it up and go singlespeed

 

[Mr Pig]

Yip, it's all about taking the pressure off the transmission to give the chain a chance to move over. If you think about it, the chain has to physically lift up off the gear and drop down onto the next one. How can it do this if you're pulling it onto the gear by peddling? When you get it right you should only hear a little click and the chain moves.

If you get caught out on a really steep hill and can't back off the pressure sometimes you can turn accross the hill for a second to give you the time to change.

 

[RedBike]

If you think about it, the chain has to physically lift up off the gear and drop down onto the next one

No it doesn't.
The chain leaves the top jockey wheel and then gets hooked on whichever sprocket it happens to align with. It doesn't need to lift off any of the sprockets. If you change gear correctly then you can more or less keep pedalling hard as you like. The only tension on the chain when leaving the top jockey wheel should be that of caused by the rear mech spring.

The problem is with changing down too many gears too quickly under hard pedalling. This causes the chain to 'twist' around the cassette running on several sprockets at once and slipping over them. This is what causes that nasty gear crunch and chains to break.

 

[Mr Pig]

It doesn't need to lift off any of the sprockets. If you change gear correctly then you can keep pedalling hard as you like.

I don't agree with you, especially on the front, and I would never advise changing gear whilst 'peddling as hard as you like'.

 

[RedBike]

The fronts slightly different as that is moved under pressure, I'm on about the back.

You're riding along somewhere mid cassette. You change down one gear (larger sprocket). As the rear mech moves across the chain will eventually come into contact with the next sprocket. As it gets hooked on that larger sprocket it doesn't suddenly jump off the sprocket it's currently running on. As the cassette turns more and more of the chain is fed onto this larger sprocket. Eventually the chain will only be in contact with the larger sprocket.

You can't pedal balls out as in a sprint because the chain will slip as it's not in contact with as many teeth as normal / then there might be gear changing issues; but normally if you're pedalling quickly and smoothly you don't need to ease up to change gear.