Bicycle Mechanics - Cassette question for a Mountain Bike

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Dman777
12-01-05, 12:24 AM
I have a 2005 6500 Trek mountain bike and I have been rideing it for about a year now. I mostly ride in gears 4-8 and the teeth have worn down on the rear Cassette to the point of needing replacement. The bike came with CASSETTESRAM 850 11-32, 8 speed. I am thinking about the dishing out the cash and getting Shimano XT cassette. If I get a higher quality cassette like the Shimano XT will the teeth last longer or will I just get better performance without the teeth lasting longer?
Thanks,
-dman
Evidently you need to invest in some chain lube as well. Replace the chain while you're at it. The wear won't automatically be reduced by throwing money at the thing. The SRAM 850 is a fine cassette in it's own right even if it is a cheaper model
HillRider
12-01-05, 07:47 AM
SRAM cassettes are fine and you won't get better wear or better performance from a Shimano cassette. However, compare prices as Shimano's lower line cassettes may cost the same or less and perform just as well as XT.
Raiyn is correct. You NEED a new chain too and should take better care of it. Lube is cheap, metal is expensive. If you wore out a cassette in a year either you do very high miles, ride in extremely abrasive conditions or do no maintainance on your chain.
BTW, what do you mean by "gears 4-8"? The five smallest cogs or the five largest cogs? If you are wearing out the five largest, that really implies difficult riding conditions and poor maintainance.
Al.canoe
12-01-05, 11:31 AM
I really like the 12 to 34 XT. My wife uses one too.That said, the bigger two cogs bend easily (I sometimes shift when out of the saddle on climbs) and I'm on my second unit because of that. That's of course a 9-speed with a very large cog. I don't think the 32's have the problem.
Next time I may try the new (2006) SRAM PG 990 11-34. They've changed the gearing a little more to my liking, though I have no use for an 11.
I put about 1200 miles on the XT I bent. No sign of cog wear. I ride in really bad sandy conditions mostly, with some mountain terrain. I use a wax lube and the basic Park chain stretch measuring tool.
I have read that the cheaper SRAM Cassttes do wear quickly. Note the 2006 SRAM unit's appear to be much higher quality than before.
Al
The wear won't automatically be reduced by throwing money at the thing. The SRAM 850 is a fine cassette in it's own right even if it is a cheaper model
I have put a custom cassette together a year+ ago, using two higher-end 9-speed Sram cassettes. As I did not think the whole thing completely through, I had two throw in a couple of smallest Shimano cogs. Recent behavior of my drivetrain suggested that some of the cogs have worn out. Subsequent measurements of the wear with the Rohloff tool have shown that all the medium down to small Sram cogs had to be changed but not the smallest Shimano cogs. Nominally, the latter should go first.
I'll be now taking a good break from the Sram cassettes.
Dman777
12-01-05, 02:16 PM
Yeah, it was the four smallest clogs that were wore out and had to be replaced. The bike mechanic said the chain was still good and had about a couple of months of life in it left. I ride my bike everyday so I don't know if the smallest clogs wore out from a lack of lubrication or just me rideing. I took the bike to the shop almost every month for maintence so it did get lubed once in awhile.
Yeah, it was the four smallest clogs that were wore out and had to be replaced. The bike mechanic said the chain was still good and had about a couple of months of life in it left. I ride my bike everyday so I don't know if the smallest clogs wore out from a lack of lubrication or just me rideing. I took the bike to the shop almost every month for maintence so it did get lubed once in awhile.
The smaller cogs generally wear out sooner because for them the given tension in the chain is spread out over fewer teeth. For the smallest cogs, this is partly compensated by the fact that one tends to use the middle cogs more than the edge cogs, but normally still not enough to prevent the smallest from going first.
There exits a brand making apparently more durable cogs than Shimano:
http://www.bbbparts.com/products/bike_parts/cassettes.html
duckliondog
12-01-05, 09:18 PM
Typically, you don't pay for strength, but for light weight. My LX cassette is all steel, and tought as can be, but it weighs a ton. My XTR is full titanium, so it actually wears faster (though not fast enough for me to have noticed anything), but it's like a feather.
I have put a custom cassette together a year+ ago, using two higher-end 9-speed Sram cassettes. As I did not think the whole thing completely through, I had two throw in a couple of smallest Shimano cogs. Recent behavior of my drivetrain suggested that some of the cogs have worn out. Subsequent measurements of the wear with the Rohloff tool have shown that all the medium down to small Sram cogs had to be changed but not the smallest Shimano cogs. Nominally, the latter should go first.
I'll be now taking a good break from the Sram cassettes.
My experience has been exactly the opposite. My SRAM cassette has outlasted all previous Shimano offerings by nearly a 2 to 1 margin.
I won't be purchasing another Shi*No cassette anytime soon
The bike mechanic said the chain was still good and had about a couple of months of life in it left. Applesauce. If the cassette is worn down in the gears you use the most you need to replace the chain as the chain is what causes the wear on the cog. Chains are (generally) cheaper than cassettes. Your wrench must be an absolute carpet smoking whiz to be able determine that you can get "a couple more months" out of a chain that's already torn up a cassette
I ride my bike everyday so I don't know if the smallest clogs wore out from a lack of lubrication or just me rideing. I took the bike to the shop almost every month for maintence so it did get lubed once in awhile.
"Once a month maybe" ain't going to cut it. If you're riding everyday you need to clean and lubricate a lot more often than that (depending on the conditions you ride in)
Dman777
12-02-05, 01:17 AM
Whats the best way to clean a chain before I relubricate it? And are there any other metal parts that I should lube often so the metal doesn't grind away?
Whats the best way to clean a chain before I relubricate it? And are there any other metal parts that I should lube often so the metal doesn't grind away?
Everything that's metal to metal and or threaded should be greased unless it came with a thread locking compound.
You don't need to spend a ton of cash for grease as commonly availiable Marine Trailer Bearing Grease ($3 at Home Depot) works perfectly well for this purpose
http://www.bikeforums.net/showthread.php?t=139241
as for the chain cleaning it gets beat to death around here so I'd suggest that next time you:
http://img245.echo.cx/img245/9869/search7ro.gif
Repost of the chain cleaning method that's been posted a gazillion times already by me
You'll need a few things.
A SRAM power link (makes chain removal a snap)
A plastic container (I'm partial to Country Time Lemonade powder containers but 20 ox Pepsi bottles work well with the wide mouth)
Some degreaser (Simple Green works well as does the dollar store's Awesome Orange))
A toothbrush (One that you no longer use for your teeth)
Water
A large rag of some kind
Remove the chain and place it in the container, then fill the container 1/2 to 3/4 full of degreaser.
Seal and shake for a minute or five.
Remove the chain.
Use the brush to get any residual gunk off (there won't be much)
Rinse the chain using water.
Proceed to do a general drying of the chain using the towel (It doesn't have to be perfect as you'll let the rest air dry.)
Reinstall and relube the dry chain
As for chain lube I've been using Boeshield T-9 for a little while now and I've been impressed with it.
Typically, you don't pay for strength, but for light weight. My LX cassette is all steel, and tought as can be, but it weighs a ton. My XTR is full titanium, so it actually wears faster (though not fast enough for me to have noticed anything), but it's like a feather.
Cogs thickness is about the same within a given speed for different manufacturers and even between different speeds the differences are not that large. Once it is steel, the differences may be in admixtures and in manufacturing. Besides you pay for finish, spider, shape details, spacers and retaining ring. In my case, all were steel and I was avoiding spiders preventing cog swapability. Extra holes in one cog or other should not impact teeth durability.
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