Replacing chain

SMITHY D

Hello

I've recently replaced my chain from a KMC (unsure which one - came with the bike) to a SRAM PC991. I'm running a SRAM PG-950 cassette on the rear and a Truvativ Fire X drivetrain on the front, XT rear, LX front derailleurs and now i'm getting 'jumping' issues when i pedal - is this a compatibility issue, or is it that the cassette/ drivetrain is worn. componenets have been on there for about 12 months and i ride 3-4 times a week?

Gears have been indexed on bike stand and i've made the chain the same size as the old one! I'm maddly trying to sort it out so I can get OUT!

Some help would be appreciated

Smithy

cunning-stunt

I'd say worn bits mate seeing as you ride so much. I try to change my chain every couple of months or so,and I generally only ride once or twice a week.

Had the exact same issues as you once before after a hectic 6 months of riding (4 or 5 times a week) without changing the chain.Finally remembered to change it but no matter what I did the drivetrain would still skip and jump.
Luckily I got away with just replacing the cassette instead of the whole caboodle..

I may be completely wrong of course,but the way you describe it sounds exactly like what I had.

SMITHY D

Thanks for the advice mate!

I think I'll replace the cassette and see if that sorts things out! I don't facny changing the chainset just yet!!

Do you know if there is anyway knowing which is causing my problem - the cassette or the chainset? Any ideas how often they tend to last in relation to how often I ride?

Smithy

cunning-stunt

Not an expert in this area tbh,you need Nick or Supersonic. But check the teeth on the cassette and chainrings to see if they've 'hooked'. Suprising how much they can wear out.
Don't take my word as Gospel mate,that's just what I think seeing as I kinda went through pretty much exactly the same once. Wait and see what those guys say before ordering new bits,just trying to help

Anonymous

gtet yourself a chain wear checking tool, check it every few rides and as the chain starts to wear, change it, it would make the rest of your drive train last much longer, a worn chain = worn drivetrain in no time.

switchback18

I've found that chainrings wear faster than the cassette, especially if they're allu ones. Some are better than others, but even the best ones still wear faster than the cassette cogs. Best chainrings I've found that are alloy are the Middleburn hardcoated. Deore are pretty good, as they're steel, and they fit non-Shimano, just heavier. Cassette wise, a Deore is about as hardwearing as an XT, just heavier. Like sheepsteeth says, get a Park chainwear guage, it's not too expensive & it'll pay for itself. You don't have to guess, so you don't let the rings & cassette wear out faster than they need to, but also you don't change the chain out of paranoia before you need to!

stumpyjon

Does sound cassette related. Same happened to me at the beginning of the year, left the chain too long and the cassette wore (and one of the front chain rings).

Just about to replace the chain again, this time hopefully I've caught it before the cassette needs replacing :roll:

switchback18

Yeh you're right. My reply sounds like I'm saying it's the rings that're the problem. But obviously if the gears are jumping, there must be a cassette issue. I just meant that if the cassete's worn, the rings almost certainly are too. Thanks for clarifying.
I've found middle rings wear the fastest, I probably replace 3 middles for every large.

stumpyjon

I find the small chain ring wears fastest, but that's probably because that's the one I use the most :oops:

SMITHY D

Cheers for the advice guys!
I've been out on the bike this afternoon, i found that when i'm climbing steek sections the chain tends to jump now and then, so i guess i'll start with the cassette and then (hopefully not) the chainset.
Sorry to keep harping on, but am i right in thinking i can mix shimano, sram and truvativ components?
one last question and then i'll shut up, can you get single rings for the chainset?

Again really appreciate you're input!

Smithy

Anonymous

you can get single chain rings but i think they are specific to different chainsets (shimano might not fit truvativ), you can mix sram cassettes with shimano or any other mtb chain of the correct speed and any correct speed mech

switchback18

Yep, even when you know the bolt circle diameter (BCD) is 104mm, there are other differences. A middle that fits an XT HTII crankset doesn't fit a Deore, but the Deore chainring will fit the XT, and just about everything else with a 104mm BCD. If you're desperate, you can file down an XT ring to fit other chainsets, this obviously isn't recommended, but works fine once fitted. It's the extra metal to the inside of the bolt holes that stops it fitting.

warrerj

Worth a read :

http://www.sheldonbrown.com/chains.html

allthegearnoidea

personally i'd also go back to a KMC chain over sram!

chainrings wise i used a ring of my old truvative fireX on my shimano set (xt m752 so not the newer ones!) and had no issues fitting wise, but as said, as long as they are the same pcd (104 for the outer 2) then you'll be fine! most places like crc list the sizes for you anyways! ebay can turn up bargains though! middleburn hardcoat slickshift rings a tenner a pop last week!
i've had to replace all three front rings this season as they were starting to cause a fair bit of chain suck but they were 4 years old so no complaints!

it doesnt harm to replace the rear cassette either, always nice having new kit hey! but check youv enot got major play in your free hub! mines shot at the mo and wobbles a fair amount! causing the chain to hop a little in certain gears, but having over spent this month it'll have to wait for a mo!