Last rites of my old cassette?

[Snoozeboy]

The third chain of my cassette is at 0.75, having changed the previous two at the same stretch. I've bought a new chain which skips like crazy on the old cassette. I don't know if this is due to the new chain being different from the previous three or because the cassette is now so worn that it doesn't grip on a new, non-stretched chain. It's a cheap SRAM PC-1110 whereas the 3 previous chains were premium price KMC x11e.

The old chain and the old cassette run fine, no skipping at all and only a small issue of sluggish changing up from 2nd biggest to 3rd biggest cog, which could be due to other things and I'm not that bothered about. I'm happy to continue with this until the cassette starts skipping, whereupon I will change it and the chain, but I don't want to risk the chain snapping and me falling off.

The cassette has about 3800km and is due for a change, in fact I've had one delivered, but I'm weighing the can't be arsed of changing it with the risk of a chain snap. I know that we're advised to change the chain at 0.5-0.75 stretch, but that's to save excess wear on the cassette, which no longer applies.

What comes first for a worn chain on a worn cassette, skipping or a snap or is there no way of telling?

Cassette is 11s Shimano SLX 11-46.

 

[steve_sordy]

Unless you have concerns about the front ring, I would run the old chain and old cassette together until the shifting becomes poor. But as the chain length increase gets to 1% it is "officially" scrap (according to the bike mags, Parktool etc). So I would not be tempted to run it past that point unless you are experimenting to see how far you can go. In which case, let us know how you get on please!

Because a badly worn chain accelerates wear on everything it runs on, when it comes time to change the cassette and chain for new ones, I strongly recommend fitting a new ring too especially if the ring is as old as the cassette.

 

[Snoozeboy]

Unless you have concerns about the front ring, I would run the old chain and old cassette together until the shifting becomes poor. But as the chain length increase gets to 1% it is "officially" scrap (according to the bike mags, Parktool etc). So I would not be tempted to run it past that point unless you are experimenting to see how far you can go. In which case, let us know how you get on please!

Because a badly worn chain accelerates wear on everything it runs on, when it comes time to change the cassette and chain for new ones, I strongly recommend fitting a new ring too especially if the ring is as old as the cassette.

Thanks for your reply. Yes, I'm not bothered about the front chain ring as it's only about 15usd to replace (old Bosch CX performance system). I'd be quite happy to go back down to the original 15 tooth from the current 16 tooth, which is about half as old as the cassette.

My Park Tool CC-3.2 chain measuring tool only goes up to 0.75 however.

Hmmm, maybe as it's a sunny day I'll bite the bullet and change out the chain and the cassette. At least, that way I'll find out if the skipping was due to a cheap chain and I can keep the old cassette as an emergency spare or whatever.

(I just hate changing stuff and throwing stuff away because the bike mags and Park Tool says so. In the old, non-e days, I used to change stuff once every many years. Now it's 4 chains/2 front rings/1cassette per year).

 

[steve_sordy]

If you are going to remove the chain, then you can measure the amount of wear with a metal tape measure. Lay the chain flat on a worktop and pull it taut. Measure pin to pin over 100 links. A new chain will measure 50". A chain with 0.75% "wear" will measure 50-3/8". A chain with 1% will measure 50-1/2". With care you should easily be able to measure to within 1/32 of an inch and therefore to 0.06% which is accurate enough for anyone.

 

[Snoozeboy]

Thanks Steve, but I'm not confident in my motivation to measure to 1/32 of an inch or even count 100 links.

Instead, I changed the cassette to a new SLX 11-46 and the chain to a cheap SRAM pc1110 (from a KMC x11e). The combination works fine, though it seemed slightly harsh and noisy at first. Maybe this was because I was used to a fair amount of gunk on the cassette and chain damping any noise.

I'll be interested to see what mileage and shifting performance I get from a SRAM pc1110, compared with the KMC x11e at 4x the price (according to prices in Switzerland).

 

[steve_sordy]

Thanks Steve, but I'm not confident in my motivation to measure to 1/32 of an inch or even count 100 links...................

Its easier than you think!
Lay out the chain on a flat surface, I use my kitchen worktop with newspaper on it. Stretch it taut, so it is straight and all the links are touching. With a metal tape measure, measure 50". With a new chain exactly 100 links will, be there, already counted. If the chain is worn, the 50" mark will look to be a bit short (because the chain has got longer).

The way to get good and repeatable accuracy is to forget using the hooked end of the tape measure. Instead line up one of the pins with (for example), the 10" line. That is a lot easier to do than trying to line up the end of the tape. Just remember that at the other end you are looking for the 60" mark!

The only snag is that if the chain is really worn, the 99th link might line up with the 50" mark. There is a quick check for that. Look at the 25" mark, if it is half way between two pins, then you have a really knackered chain!

If all else fails, you have to count!

Isn't it great that despite metrication, chain and chain rings with half-inch pitch are still produced all over the world? Making chains with 12 or 13 mm pitch would be easy to do, if starting from scratch, but there is a huge investment all over the world in machinery that produces half-inch pitch stuff. Why fix what isn't broken?