Bent cassette on commuter - what gives?

wolfsbane2k

Hi.
I've got a 7 month old btwin 500se that's done about 800 miles and after a good clean and inspection in the sun today the teeth on the three smaller cogs look twisted by about 15/20 degrees, front edge towards the smaller rings. I don't recall noticing this before, but this is my first proper strip down clean since I've owned the bike, so I'm not sure how much bend to assist with gear changes is normal.

It's a sunace 12-25 8 speed, so not expecting a lot, but 800 miles is to little!

As a precaution I've ordered a new Sora 12-25 8 speed, but want to understand what might have caused this, and how to avoid it in the future. I'm assuming it's heavy changes and possibly a bit too much cross chaining rather than anything else. The hanger, and front chainrings all look OK.

For £15 for the Sora not worth taking it back under warranty, I'm assuming it's something I'm doing, unless it's just too much force for the thing, caused by my weight and a big hill I slog over!
Cheers!

homers_double

Do you mean they sort of lean forwards like a leaning peak?

wolfsbane2k

homers double wrote:

Do you mean they sort of lean forwards like a leaning peak?

No, it's more that they seem to twist up laterally, if you look down on them the edge towards the rear of the bike is pointing towards the wheel by about 20 degrees on a couple of teeth on a few sprockets.

Compared to my 7 year old xt MTB rear cassette which has almost none like this, but has a lot more protrusions & indents in the cassette for transfer assistance.

nicklouse

Pictures will help.

frisbee

In a bike rack at work? Some people seem to be unable to insert their bike into the rack without destroying 3 other bikes, maybe they've managed to damage your cassette somehow.

fenix

I can't see how you'd manage to bend sprockets like that. Are you sure it's not for changing gear?

TBH unless it's causing problem I'd not change it. If it's that bent as you say it must be impossible to change gears.

Paul 8v

I think you're actually Robert Forstermann. That'd do it!

Bobbinogs

I reckon you might have goosed the cogs by shifting under load. There is a technique to shifting mid-climb and it can be done (just ease off, shift crisply and turn the cranks carefully until the chain has shifted across and then put the power down) although sometimes if the road kicks up suddenly and you have been caught out then it is better to try and grind it out until you get the chance to shift safely.

Sounds like you need a new cassette and some practice at shifting. Oh, and avoid cross chaining under load!

wolfsbane2k

Delayed response: sorry.
Having taken the opportunity to take photo's of a new sunrace cassette, it's actually part of the build, just looks odd - obviously didn't look at it that closely before!

fenix

Well i hate to say I told you so but..... ;-)

Glad its all resolved at no cost !

wolfsbane2k

fenix wrote:

Well i hate to say I told you so but..... ;-)

Glad its all resolved at no cost !

Indeed you did!

I was comparing it to an old 9 speed xt cassette on the MTB to start with, which has more ramps than twisted cogs.
However, I did buy a new sora cassette at the outlandish price of £10, which I've still got in my garage for when this does die.

DavidJB

Bobbinogs wrote:

I reckon you might have goosed the cogs by shifting under load. There is a technique to shifting mid-climb and it can be done (just ease off, shift crisply and turn the cranks carefully until the chain has shifted across and then put the power down) although sometimes if the road kicks up suddenly and you have been caught out then it is better to try and grind it out until you get the chance to shift safely.

Sounds like you need a new cassette and some practice at shifting. Oh, and avoid cross chaining under load!

Lol people talk some utter drivel on here. ffs.