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XT Cassette Loses It's Battle.....

8K views 85 replies 23 participants last post by  jonshonda 
#1 ·
Against diesel torque.

Maybe 300 miles on this bad boy.

The bike was just sitting there....and all of the sudden POP, crash, grind. It was broken. :p

Something look funny?

002 by jonshonda187, on Flickr

Broken

003 by jonshonda187, on Flickr

Yup...it broke

005 by jonshonda187, on Flickr


006 by jonshonda187, on Flickr
 
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#7 ·
Had that happen to me, I don't know, maybe 6-7 years ago. XT cassette snapped the same way. But I had a lot more than 300 on mine. I push the big gears, not a spinner, but have not have it happen again. Changed to Sram after that, and had no problems since. Back on XT for the moment, so will see. I don't anticipate any problems.
 
#9 ·
The power you generate on the bike has very little to do with weight or size. If it did, pro cyclists would all be 6'6" and 400lbs. If it did, 300 miles would be normal for a cassette. It isn't.
So - what were you doing? Mashing the same big gears up every hill? Hucking big jumps with a too-short chain and bad landing technique? Bad spannering?
Materials do not just give up and fail - something has to be putting them under unusual stresses and that isn't usually from riding a bike using smooth gear changes and a flowing technique.

I've just read your other discussions of this on other threads:

The past year has seen; 5 bottom brackets, a x9 crank set, hope pro2 fh body, spesh seat, one pedal, two broken spokes, two cassettes, a few different seat post clamps, cracked (in three places) frame, specialized seat post, one chain, and more hours maintaining that i would care to admit.
Bad spannering or user error - no doubt. That sort of failure rate is way beyond normal.
 
#11 ·
TooTallUK, I cannot tell if troll or serious?

The power you generate on the bike has very little to do with weight or size. If it did, pro cyclists would all be 6'6" and 400lbs..
You are stating that a 150lb rider standing, mashing up a hill, will generate the same forces on the drivetrain as a 275lb rider? The physical act of me standing up and applying my weight (weight only) to a crank arm = nearly double the force of a 150lb rider doing the same. Heck, the force required to even get me up a hill is nearly double.

The reason pro's are not 6'6" and 400 lbs also has a lot to do with physics. Easy comparision. A cadillac vs. mini cooper on a road race course. Cadillac requires lots of power to get up to speed, keep up to speed, brake, turn. It needs a much larger moter, much heavier components, much more room to move around, larger brakes etc....
A Mini Cooper is small, nimble, weights much less therefore requires much less to move it around a track.

According to your logic, you are implying that the same force required to move 150lb load is equal to the force required to move a 275 lb load? That is false. If we lived in ZERO gravity, this would be true. I am not riding a moonlander, so that logic does not apply.

So - what were you doing? Mashing the same big gears up every hill? Hucking big jumps with a too-short chain and bad landing technique? Bad spannering? .
The situation is rooty rocky flat to large steep hill. Standing on this is common for many riders here, as it is also rooty and very rocky, so sitting is difficult.
Bad spannering (had to look this up) is not out of the question, but I have a pretty new KMC chain, and the cassette was hanging on a brand new PRO 2 hub, tighten down to spec.

Materials do not just give up and fail - something has to be putting them under unusual stresses and that isn't usually from riding a bike using smooth gear changes and a flowing technique. .
Materials just don't give up and fail. I will spread the news to engineers everywhere, their worries are over!! :madman: :nono:

The stresses you are reffering to are simple. I am using a cummings deisel on a drivetrain mostly designed for a Honda four cylinder. :thumbsup:
 
#12 ·
As a 250lbs+, 6'7" tall, 21 year mountain biker, I am not shooting blind here. Aluminium doesn't just fail, steel doesn't turn to cheese - it does not just 'give up and fail'. Something has to happen in order to make it fail. Too many big riders blame their size for what is user error.
 
#13 ·
As I said - materials do not just fail - you have to do something to them in order to fail.

Your track record of multiple bottom brackets etc tell me that poor maintenance has a bigger part to play than you weighing a little more than me.

a drivetrain mostly designed for a Honda four cylinder
Rather than just guessing, do you know the actual numbers for the design of a drivetrain, or any other part for that matter? I've not seen anyone come up with actual numbers for much, but an average bike chain will fail at about 2000lbs load - which you are not generating. So many people say it isn't designed for 'us' but I have yet to see numbers to back that up.
 
#14 ·
jonshonda's 9:ZERO:7 speaking. I can confirm that jonshonda does in fact follow good maintenance practices, keeps me clean and well lubed in all the right places. He is hard on me sometimes, but that is how I like it. I can also confirm that jonshonda was standing and mashing at the time of my cassette failure. No wrong doing was occuring at the time of failure.

Straight from the horses mouth. What other proof do you need?
 
#65 ·
#dead!!!!! . I died laughing after reading this reply ....hahahahaha I too have snapped sram cassete, xt chains......... no offense 250lbs in my opinion is like a baby clyde..lol...they still fit into the markets weight margin..but 330lb cleary does not.. ive had to go hd (heavy duty) on a lot of parts just because size does matter
 
#16 ·
Actually, you guys argue over a false dillema.

Materials do fail on their own. Just like assembly may be faulty. For example a bit too little preload of the rivets on the cassette carrier will suffice to cause, over time, damage like in OPs pictures. Even the best QC cannot account for all flaws in a product. That is why warranties exist.

Granted, equipment with flaws that would not bother 150lb rider, may surface when abused by a clyde. However, most bicycle parts are way overbuilt for their intended purpose. No manufacturer will risk 50% failure rate at a cost of 20 or so grams.

In my opinion the cassete should be warrantied.
 
#17 ·
Actually, you guys argue over a false dillema.

Granted, equipment with flaws that would not bother 150lb rider, may surface when abused by a clyde. However, most bicycle parts are way overbuilt for their intended purpose. No manufacturer will risk 50% failure rate at a cost of 20 or so grams.

In my opinion the cassete should be warrantied.
Shimano agreed that it is a warranty issue.

Engineers design the product with a certain safety factor for its intended usage. The higher the safety factor, the higher the cost and weight ( depending on material selection). If the intended design was for a certain range of rider size, the safety factor will be based off the range. The designers aren't creating cassettes for the heavy riders, because that percentage of riders falls well out of the bell curve based on the typical rider.
 
#20 ·
Yeah clearly certain brands of parts are designed for certain things. Saint stuff will handle more abuse than XTR, for instance. And, yes, some parts do break when you are 'just riding along', but it seems like the concern is the volume of parts that are being broken. I would say that something would need to change, be it the type of parts you are using, or riding habits.
 
#21 · (Edited)
Got everything bolted back together and hit the trails. Lately I have been getting funky noise coming from the crank set area (only while on the granny gear). So I took the ring off, cleaned, greased, and applied lock tight to the bolts (I have been noticing them losening up after each ride).

90% of the ride went off without a hitch. Then I noticed the chain was getting bound up on the granny ring (aka CHAINSUCK!!). I know I put it on correctly and it is bolted tight. Switch to the big ring.... boom, issue gone. No noise, no binding.

Looks like I have a worn out raceface turbine chainring? How is that user error?
 
#25 ·
I was kinda joking about the user error part.

Chain line may be poor. I will have to take measurments to determine if I should remove one spacer from the drive side.

Chain gets a mineral spirits bath followed by Pro Link Gold fairly often. I did inspect the links that were binding up and they appeared to be moving freely.

Chain length was determined using the Park Tool diy section, and verified ok by LBS.

I have a long cage X9 rear der which is less than a year old. I will inspect it for function. What would help me determine if it is not functioning properly?
 
#29 ·
I actually broke an XT cassette in that exact same fashion last month. It was the same cog that pulled off. At the time I was standing up to muscle out the last 20 feet of a steep climb. I'm 250#. Shimano warrantied it. No abuse. It would seem that that particular part of the cassette body is not up to the force that a clyde can put down.
 
#32 ·
Think about "torque". You can be a professional cyclist or just an average joe that weighs 300# and mashes the crap out of the pedals... Where is almost all of the torque at? The chainrings! The cassette sees some force, but really with the chain tracking through the guide wheels(jockey wheels) and then up and around the cassette, doesn't see nearly as much force as the chainrings. So to see a cassette come apart like that after 300 miles is pretty interesting.

I'm 6'2 250# and I have over 400 miles of training and xc-racing on my SLX cassette and it still looks like new.
 
#33 ·
Ummm...I don't think that is logical. I put power through the pedal, crankarm, chainring, chain, and into the cassette to turn the rear wheel. I am sure the chain gives up a little power through friction, but the cassette is going to see just as much if not more torque. The lowest (largest cog) on the cassette will apply the greatest amount of torque. Think of the largest cog as a long breaker bar, and the smallest cog as a short breaker bar. You want to break a bolt loose, which breaker bar do you choose? THE BIG ONE!!

Long story short, the cassette gets diesel torqued.
 
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