How worn is this cassette?

bluechair84

The gears are slipping high torque. At first it was the smaller gears which made sense to slip as there are fewer teeth but now it seems to include the mid range. The trouble is I don't think this looks that badly worn. There is some play in the mech's knuckles too and I wonder if that could be worsening it.



Thanks

nwmlarge

looks like wear to the more commonly used gears to me
the dips are elongated and certainly steeper on the right hand side of each dip

bluechair84

but is this sort of wear expected? Would you think that there should be more milleage in this cassette? I don't want to bin it for a new cassette if this is likely not the cause of the slipping as I've just spent £300 on the bike
Next investigation will be the pawls but I doubt that's the issue as it doesn't slip in all gears.

cooldad

Er what mileage. My ESP is weak today.

anjs

oh and how is the chain. Have you measured it?

bluechair84

Just fitted a new chain and chain rings (i know, should change cassette too), and cooldad... Que? Was meaning I should be able to get a fair few miles out of her yet... Unless someone points out that it's way past prime and they aren't surprised it's slipping.

cooldad

bluechair84 wrote:

but is this sort of wear expected? Would you think that there should be more milleage in this cassette?

That's what you asked. How long is a piece of string?

bluechair84

What i'm trying to determine is whether this level of wear should be leading to slipping gears, and not a distance figure. Like "well i'd say it's half way worn" gives me some indication of life span. Your rhetotic radar is down, or my rhetoric don't come out right :?

cooldad

If it's slipping, and everything else is new, it needs replacing.
Don't think it's really possible to determine the degree of wear from a pic.

ricardo_smooth

cooldad wrote:

That's what you asked. How long is a piece of string?

Double half it's length! :P

bluechair84

cooldad wrote:

If it's slipping, and everything else is new, it needs replacing.
Don't think it's really possible to determine the degree of wear from a pic.

Aye, might just have to bite the bullet and go for it, which means I've replaced the full tranny then. But at a time when I've tacoed a wheel, knackered a seatpost, reduced the pads to dusts and broken a shifter - just through wear and tear... Bloody expensive month!






#hands credit card back to CRC with an unhappy face#

sponsoryu

Keep going, I used mine till one ended up snapping


*takes great care of bikes.. cough*

cooldad

sponsoryu wrote:

Keep going, I used mine till one ended up snapping


*takes great care of bikes.. cough*

You snapped a cassette? Think you missed the question.

tsenior

he snapped his credit card i think

bluechair84

well, just before I ordered a new one tonight I thought I'd do a comparison with a picture of a new SLX cassette:

The right hand side of each hollow definatly looks steeper on mine and the new one...
Might brave the inside of the freehub tomorrow and clean out the pawls before I spend another £40. I don't think my cassette looks particularly worn but can't figure out why the higher gears would slip otherwise.

concorde

I don't think it looks particularly worn at all. Especially when not compared with that brand new one!

BG2000

It's not easy to see tooth wear with most modern cassettes as the teeth are not symmetrical to begin with, as your piccie of an HG80 shows.

But as nwmlarge has already said, there is visible wear on the commonly used sprockets of your cassette which is usually the 3rd and 4th smallest on a 9spd. You can see that the gradient of the upward curve (LHS of tooth) is steeper. If you use a new chain with this cassette the gap between the LHS edge of each sprocket tooth is more (in mm) than the gap between each roller on the new chain. If these two dimensions don't match up, the chain will want to roll up off the tooth, and you chain will suddently slip if you pedal hard.

This won't happen as much on the smallest sprockets as the chain is so tightly wrapped round them. It won't happen much on the largest sprockets as there are roughy twice as many teeth to wear out, so they last twice as long.

And to repeat what I've already said, it's the middle/higher sprockets that always get used most, for various reasons: the chain line is about right so it doesn't scrape on your front derailleur, 44 x 17 is a nice gear for getting along the flat sections, it's roughly in the middle, so you can go higher or lower easily without worrying about running out of gears etc...

I've had to replace many cassettes simply because one of two of the sprockets are too worn to work with a new chain. It's very annoying, and I wish it was easier to replace individual sprockets.

The cheapest solution many people find is to replace your chain when it gets to 0.75% wear. If you do this, and then replace again at 0.75% wear, you should find that your cassette lasts longer this way, compared to waiting for your chain to get really worn, at which point it's too late and a new chain won't work. So it might seem more expensive at first, but will pay for itself long term. That's why Park Tools sell the chain stretch tool. They don't make any money if you buy a new chain, so there must be a reason they sell those tools.

Sorry for the long answer. I wonder how many chains have worn out since I started writing this

bluechair84

right-o, thanks all. Looks like a new cassette is on it's way. Along with some rubbing alcohol too for the rotors.
Thanks for all your analysis

joshtp

I was disapointed in my SLX cassette.. wore out quickly. Same issue of a new chain caused jumping in a few gears...

bluechair84

I wonder if an XT cassette would last longer. The SLX and XT gear is supposed to be very similar. A quick look on Shimano.com says XT is chrome plated steel, SLX is chrome/nicel plated steel. I wonder if the full chrome on the XT is £8 more worth it...

omegas

I would get a Deore, A bit more weight but more durable.

BG2000

I'm not aware that the sprocket base metal is harder on one model compared to another. So I don't think it matters which model you get in terms of how long it will last.

The exception is the titanium sprockets used on XTR, but those are only the largest 5, which are the one's that don't get worn as much (it's really only to keep weight down).

When you pay more for the higher end cassettes, it's usually because they incorporate an alloy spider to save weight/improve mud clearing. In my experience, they don't last any longer. I always end up wearing out the 16,15,14 sprockets etc..

One idea is to get a top end cassette with spider, then when the smaller sprockets wear out, buy a Deore or PC950 and just take the sprockets you need from these. Then you still have a lightweight high performance cassette, but only paid £20 to replace the worn sprockets.

njee20

So how many miles has it done? As Cooldad says, asking if it should last longer, when you don't say if you've done 20, or 360000 miles makes it harder to advise.

It looks pretty knackered to me, visible burrs and what not. If you don't want to spend the money put the old chain back on and keep running the old transmission for longer.

bluechair84

well, a very rough estimate might be 1600miles, based on 20miles a week for it's first year and a half and not much more on top since moving to newark.
I can't run the old transmission because the slipping is a bloody nightmare to get a rhythm going on an incline. What I wanted to establish though is if it's likely to be the cassette or something else. But everyone seems to agree it looks worn so I'll pick up a new SLX soon.

njee20

If I got 18 months out of a cassette I'd jump for joy, let alone the amount of time since you moved to Newark. Just do it. HG50 if you're on a budget, HG80 if you've got a bit more to spend, XT if you want to protect your freehub body.

bluechair84

Cheers... with the rate of wear i'm giving my kit I can't justify spending on XT :roll: I'd have a very fancy dust collector in the shed! Fortunately big plans for the Summer. SLX will be the one.

njee20

I'd think of that the other way round, it'll last so long so you may as well get the pricey one! Just get a SRAM XG-999 and have done with it!

bluechair84

yup... if I buy that from the wrong store (ie not the cheapest place) that will nearly double what I've spent on the bike this month... I bet it don't last 5 times longer though