Identifying a worn cassette

drwae

I have been experiencing a problem with my rear shifting which suddenly started a few weeks ago. If I try to shift down to a smaller/lower-teeth gear, sometimes it takes 30 seconds to shift or I will even have to go down two gears and back up one, or down three gears and back up two! :shock:
I replaced all cables and housing on the bike and the problem persisted. I have tried adjusting the gears on the rear derailleur myself and even had it done in my LBS and the same problem persists.
Also, the problem only seems to occur around the middle range of the cassette. I can't say I have ever noticed an issue going e.g. from the largest gear to the second-largest or from the second-smallest to the smallest, but I could be mistaken.

I replaced the chain a few weeks ago it was ~0.85-9% worn as a guess, with the checker tool the 0.75% side went in easily and the 1% side was not quite going in (yes I left it too long).

Is anyone able to tell if my cassette is worn and needs to be replaced? I don't know what to look for, myself.
Here is a picture of my cassette: http://i.imgur.com/jFoSf2y.jpg
I do normally keep my bike cleaner so please ignore the dirt, I've been riding in the rain and all my muc-off stuff is on the other side of the country for now. :oops:

Cheers

svetty

It could be cassette wear but it sounds more like either the cable or the rear mech. Given that you have replaced the cable and housing I'd check the pivots on the mech are moving freely. They may need a dismantle, clean and re-greasing.

Bobbinogs

I would also check the jockey wheels, predominantly the top one (the guide). They can develop a lot of play which then results in lazy shifting both ways. Easily fixed by spending a tenner on a new set. If this doesn't solve the issue then stick the old ones back on and keep the new ones for spare...always handy.
Regarding the cassette, it is very difficult to tell a worn cassette from looking at it. The usual symptoms are poor shifting but also skipping.

keef66

^ wot they said. A worn cassette is hard to spot by eye, it usually manifests itself when you fit a new chain and it starts skipping forwards over the teeth when you stomp on the pedals.

Sluggish gear changes in the direction you describe are usually down to cable friction, often in the short loop of outer near the derailleur. But you've replaced that, so it's either the pivots seizing up in the rear mech, the return spring is knackered, or the jockey wheels are slopping about too much.

Watching the mech during the sluggish gear changes with the bike on the workstand should tell you if it's the mech moving late or the jockey wheels failing to redirect the chain.

drwae

Thanks guys I will check the derailleur next. Just from a quick check of the jockey wheels there is no play in them.
Are these 'shark teeth' i.e. worn cassette? http://i.imgur.com/cORRETr.jpg
Also, when the gears take a long time to shift, I can hear it clunking away as if it's only half-shifted / failing to engage the teeth correctly.

slowbike

looks a bit dirty too - if the rear mech is similar that gunge will result in poor shifting...

drwae

keef66 wrote:

Watching the mech during the sluggish gear changes with the bike on the workstand should tell you if it's the mech moving late or the jockey wheels failing to redirect the chain.

I can't seem to replicate the issue when I'm not actually riding the bike , it shifts fine if I'm just holding the rear wheel in the air and spinning the pedals by hand.

Slowbike wrote:

looks a bit dirty too - if the rear mech is similar that gunge will result in poor shifting...

It is dirty right now but even when I had the whole bike spotless and shiny I had the same issue.