Hey all,

I recently bought a bicycle that I took to be higher end for an Indian brand. I use it for daily commuting 20km round trip and for riding around just for fun. In the 3 weeks I've owned it I've done about 550km total, on a mix of paved and dirt roads.

The smallest cog on the shimano 8 speed cassette is already visibly damaged. It goes ca-clunk when I pedal really hard/accelerate/stand on the pedals in the highest gear. I generally ride in a high gear. I don't want to just replace the cassette if I don't have an explanation for why this one wore out so fast. I've owned other bicycles in other countries, have always ridden almost exclusively in the highest gear and never run into this problem before.

Any ideas?

visible damage how broken tooth?

does the clunk sound align with where the joining link is when it goes clunk?

is the chain sized properly to the bike?

a tight joining link will cause what you describe.

Given it is 8 speed and new the bike is not on the high end but that does not mean it should not function properly nor that is a poor bike. Often assembly of bikes in general lack proper procedure. Chain Length is key to proper shifting and smooth operation. A sticky joining link or any link can cause jumps especially in a high gear. Often this can be fixed by working the stuck link once found by simply moving it back and forth and using lubricant.

Taking it to mechanic if this is beyond your skill would be wise. A stuck link can damage the cog and make the repair more difficult and costly

If you only care to ride in one gear, why not get a single-speed bike and make it official? With no extra slack chain for the derailleur, you won't have to worry about skipping anymore.

The smallest cog of most cassettes these days is an 11 or 12. That forces the chain to bend at a tight angle around it, and that wears out the chain (and that cog) faster than if you spread out the wear among the other cogs.

Yeah, I had a really cheap single speed for a while. The gear was annoyingly low and I wanted a bike I could use for all of the things I was using that one for- rural exploring over rough terrain, daily commute in the city, and occasional overnight trips hauling some gear. It's been a good bike aside from this one issue. I can do jumps on Calcutta's comically huge speed bumps that most vehicles have to come to a near-complete stop for and it's comfortable on rough gravel roads. I have a tiny apartment and room for only one bike.

It's not very damaged, it just looks worn down and sharpened.

There didn't appear to be a stuck link but I lubricated the chain anyway.

When you ask if the chain is the right size are you asking if it's too long (ie I should take a link out) or if it's just an incompatible chain?

The clunking sound doesn't seem to line up with any particular place on the chain but it's hard to tell as I can't replicate it when the bike is sitting still. It only happens when I'm pedalling hard.

I haven't found a competent bicycle mechanic here. I took it back to where I bought it and the "mechanic" who assembled it had no idea what was wrong.

there some great videos on park tool for repairing your own bike. Have you inspected adjusted your derailleur? Sorry I did not think of that the first round. It will cause what you describe. I am not saying your cog is not worn it would be unusual for it being so new however

here is a link to a video there are tons of videos out there

11T cogs on most cassettes look a little more shark-toothed than the bigger ones anyway. Rarely do they wear out - they get used far less than those in teh middle (3-4-5-6 on an 8-speed). Compare the shape on the smallest cog on this Altus cassette to the rest (sorry about the big pic).

Edit: dang, won't let me post image or other URLS until I have 10 posts.

It seems to me you are far more likely to have an adjustment issue, or more probably a bent derailleur hanger.

Straighten the hanger before trying to adjust the gears or you will be chasing your tail.

And lets try this again

And maybe one last time... here we go. Cassette image


Here's how I do it out on the trail when I take a hit to the hanger. (Hilarious that this vid is done by a young teenager but the advice is 100% solid )

Derailleur slightly out of alignment,,, or derailleur hanger bent? Have you tried adjusting cable tension? I doubt if there is anything wrong with the cassette.