RAGE AT MY GEARS JUMPING!

richardjiles

Someone fucking help me its been going on for a year now, my gears wont work, i bought a cassette to fix the problem but then that started jumping again, so i bought a new chain, gear 8 wouldnt work properly but okay, just keep it on 7 for my "high" gear, but I was out tonight and that started jumping!!! I look down and one of the teeth has that fucking shark tooth look!!!! no!!!!! its like my bike is cursed
now here is what I want to know, my other bike, a kona fire mountain deluxe, has never had any gear problems whatso ever, and I have way more miles on those gears
Now the ones on my current bike (Schwinn mesa disc) are the lower end sram ones and so seeing as I used to go up mountains, am I too powerful for these gears?

Oh and dont tell me to realign gears thats not the problem, just saying before you all suggest

Do my cranks look worn to you? best to look on actuall photobucket page

http://i1119.photobucket.com/albums/k63 ... Cranks.jpg

bails87

Bent mech hanger?

Incorrect cable routing?

mrmonkfinger

richardjiles wrote:

i bought a cassette to fix the problem but then that started jumping again

did it fix it for a while?

richardjiles wrote:

so i bought a new chain, gear 8 wouldnt work properly but okay

but other gears were fine? probably misaligned hangar or end stop (H/L) screws on the derailleur

richardjiles wrote:

just keep it on 7 for my "high" gear, but I was out tonight and that started jumping!!! I look down and one of the teeth has that ******* shark tooth look!!!! no!!!!!

so cassette looks worn?

FYI (and it might not be this causing the problem, but...) if you use a new cassette with a knackered chain, the cassette can get knackered real quick. so its always best to do both together if you swap the cassette.


if its not the alignment and the gear hangar & derailleur are both definitely straight, I'd swap both chain & cassette (and chainrings if they look worn) for new. but of course, check the derailleur is set up properly first. end stop screws particularly

Diddly

check chain (get a chain stretch tool), cassette & chain rings. might need to replace all 3 if they all look worn to stop the jumping.

nicklouse

so you use it running poorly and wonder why things wear out fast?

or you have no idea what the teeth should look like you do know they are not the same shape and size?

and after a year you still have not taken it to someone that can?

expaext to replave most of the drive train if you are unlucky.

but most likely a bent mech hanger.

but it may not be.

konadawg

"my gears wont work" etc is spectacularly vague but here's my take on it.

If your chain is coming off the cassette, most likely it is not... (!)

Generally, with a steel cassette, the first to wear and give problems is the middle FRONT chainring, when the chain flies off this, it also comes off the cassette in most cases, and it is hard to determine which end is the problem. But, I have NEVER replaced a steel cassette - maybe I'm lucky - maybe it's not muddy enough here - but I have replaced plenty of front middle rings in the past.

I have seen plenty of guys have their cassette replaced unnecessarily on the recommendation of some dumb bike shop junior mechanic - to no avail - then the middle or the entire crankset is replaced and all is well.

If your shifting is not so hot - have you ever replaced your cables? Outers mainly, but obviously inners are a no brainer so they are done together.

However Sram are generally more tolerant of poor cables than Shimano.

richardjiles

Yeah I replace cables often, wow never thought it might be the middle front chain ring, but here is a few more words on gears 7 and 8 it now jumps, so i moved up to six, thrashed it up a hill and no jumping...

richardjiles

posted new picture please take a look

konadawg

Not easy to tell from a pic - in fact often not easy to tell from looking at the actual thing.

Here's a test. With the chain on the middle - or any ring you are suspecting - bike inverted - rear brake pressed - apply quite a bit of pressure to the cranks, as if you were pedalling. When the rings are worn, the chain will appear to want to lift off the ring at the lower edge (or was it upper?), this will be easily visible, you apply pressure and the chain starts lifting.

What happens eventually and under sufficient pressure is that the chain flies off the ring suddenly and violently, also coming off the cassette.

richardjiles

konadawg wrote:

Not easy to tell from a pic - in fact often not easy to tell from looking at the actual thing.

Here's a test. With the chain on the middle - or any ring you are suspecting - bike inverted - rear brake pressed - apply quite a bit of pressure to the cranks, as if you were pedalling. When the rings are worn, the chain will appear to want to lift off the ring at the lower edge (or was it upper?), this will be easily visible, you apply pressure and the chain starts lifting.

What happens eventually and under sufficient pressure is that the chain flies off the ring suddenly and violently, also coming off the cassette.

WOW! fuck me! it is moving so much on the front crank, can't believe i overlooked the front crank!
alright so I need to know how to replace it cheaply, as this is on my commuter bike, do you think I can just buy some chainrings online? or do i have to buy a whole crankset?

richardjiles

bump - also are we aloud to bump on this forum?

The Rookie

Looking at that photo, you need a whole new chainset as the individual rings can't be replaced, eBay is your best bet, just get a like for like replacement.

snotty badger

IME once one parts worn so much it causes problems it all needs replaced. Otherwise you are just chucking money away.