Snapped Chain requires new cassette?

12boy

Über Member
Location
Casper WY USA
I thinks its a good idea to change my 12 tooth Brompton sprocket along with the chain as it is heavily used since little wheels must turn many more revs. Bikes with multiple speeds sprockets last a lot longer. As far as master links go, they are chain specific, so a 9 speed chain may take a narrower master link than a 7-8. Most LBS can sell you links without a chain, and a couple in your carry-with tool kit are nice, in case you drop and lose one while fixing a chain. While very useful, they. can be tricky in cold, wet or dirty conditions whereas a good chain breaker tool will always work, although you may have to wiggle the links involved sideways to loosen them once put together. Like flat tires, there is a big difference in crouching in the rain or snow to fix something and doing it in a warm, dry workplace. Definitely, if you go the master link route, practice taking one apart a few times at home.
 
Hi all,

I am a beginner so I have no idea... My question is... is this for real or is he trying to scam me? If I have to change the cassette I will do it, no problem, but this sounds weird to me...

Thanks!
During the 40 odd years I have been cycle touring and Mountian biking I have never broken a chain (fingers crossed) however I know a lot of beginners that have, in the main it seems to be using the wrong gears, like standing on the pedels to flog up hill in to high a gear , one of the reason we have gears is to relieve the strain on us and on the drive system.

Without knowing what state your chain or cassete was prior to the chain snapping its hard to understand what has caused your chain to snap. I try to get at least 3500 miles out of a chain and cassette before replacing them together depending on which conditions the bike is being used in.
 

boydj

Guru
Location
Paisley
If you commute in all weathers you'll break a chain eventually, even if you check and clean your chain regularly - I've done it twice. You should check your chain for wear frequently and change it when required to get the maximum use out of your cassette.
 
Hi all,

During my commute this morning my chain snapped. I took the bike to the shop as I had no tools or knowledge on how to replace it (specially in the middle of the street and having a meeting in the morning).
The guy in the bike shop told me that, as I through away the snapped chain he would have to change the cassette. That they have to be replaced together... if not I will have problems with the new chain...

I am a beginner so I have no idea... My question is... is this for real or is he trying to scam me? If I have to change the cassette I will do it, no problem, but this sounds weird to me...

Thanks!
‘Best practice’ dictates that he’s right. The chain and cassette ‘mesh’ in unison. Replacing one without the other, simultaneously, can lead to the new chain slipping, under high force. However, in reality, unless the chain and cassette that were originally on were worn out, you could get more than one chains worth out of each cassette.
 

Apollonius

Über Member
I don't see how the shop could do anything other than change both chain and cassette. You only know your cassette is worn out when it slips with the new chain. The shop could not send a customer away with the chance of that happening.

Obviously, for a rider who knows what to do, changing a chain and cassette is a simple routine task, but if you don't know how to do it and don't have the tools, then you have to pay up. Might be an incentive there to learn, invest in the tools, and progress as a cyclist.
 

hawaiiguy

New Member
Location
Kaneohe, Hawaii
I try to get at least 3500 miles out of a chain and cassette before replacing them together depending on which conditions the bike is being used in.
With close to 15k miles on my bike (Giant Defy 5) without a change of chain or cassette, I think it's time. I've done it before on my previous bike (Giant Escape 3) but may need different tools to remove the cassette from the current one. I'll report on how it goes later.
 

andrew_s

Guru
Location
Gloucester
During my commute this morning my chain snapped.
The guy in the bike shop told me that, as I through away the snapped chain he would have to change the cassette. That they have to be replaced together... if not I will have problems with the new chain...
I am a beginner so I have no idea... My question is... is this for real or is he trying to scam me?
If a chain breaks, the possible courses of action are...
1) Remove the remains of the broken link with a chain tool and fit a quick link
2) Measure the chain, and if it's not too worn (up to 0.75%), just fit a new chain, otherwise (4)
3) Fit a new chain and take a chance on the chain slipping on the cassette. If it does slip, there's a chance you could crash as a result.
4) Fit a new chain and cassette.

If you've thrown away the broken chain, (1) and (2) aren't possible, and a responsible bike shop won't do (3), which leaves what happened - a new chain and cassette.

Causes of broken chains I've come across are...
1) Manufacturing defect. No personal experience, but I've seen the photos of the broken chain cleaned and coiled up to show half a dozen other links cracked but not yet broken (cracks in outer side-plate from the pin outwards).
2) Badly joined. Rare now most chains are joined using quick links.
3) Trying to change gear whilst exerting maximum push on the pedals. Back in the day, you'd just get scraping noises and no change if you tried to change whilst pushing hard, so you learnt to change whilst still pedalling reasonably briskly, and to ease off the pedal pressure during the change, but since Mr Shimano made changes under pressure work (mostly), many more recent cyclists expect to be able to change however hard they may be pushing on the pedals.
 
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