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  1. #1
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    Which cassette, XTR or XT?

    Sorry if this was asked before, but what was the main reason for XTR using titanium for the 4 largest cogs? Was is just for weight savings? Or are they more durable than the XT equivalent. (XT is what, alum? Steel?)

  2. #2
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    Besides some weight savings, actually not much unless you're a weight weenie, the benefit of ti is strength.

    When cranking up some steep hill, think of the force on your drivetrain. The largest cogs take a beating, along with the chain, chainrings, cranks, the whole bike for that matter. Especially if you're a big dude, standing and grinding. Some have actually bent XT cogs when grinding uphill. The small cogs don't have that same kind of torque on them.

    But wow, the price of those XTRs!! Forget it. I've never bent a cog. I'd rather go through two XT cassettes for the price of one XTR.

  3. #3
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    it's just weight and probably and effort to make it more expensive.

    Ti is not as strong as steel, for the same dimensions. That's why they don't use it in the smaller cogs - larger cogs have more teeth to spread load around, a Ti 11t cog would wear to the point of being unuseable in about a week (if you ever really used it). XTR is very slightly lighter, will not last as long and costs a hell of a lot more than XT. Bascically IMO you'd be a fool to ride an xtr cassette unless someone was paying you to.

  4. #4
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    If you're looking to build a racebike as light as possible XTR is the way to go. The 11-34 is almost 60g lighter than any other cassette of the same size. Not huge but a fairly significant difference for just a single component and its purpose. For anything else its really just a total waste of money.

    Besides the 4 Ti cogs the finish on the steel cogs is a little better. Instead of the chrome plated finish which chips off over time, the XTR uses some sort of coating which prevents the steel from rusting and also seems to shift slightly more smoothly and quietly.

  5. #5
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    A buddy of mine swears by his xtr ti cogs... he wants all ti... he says they will "never" wear out. He runs big ring a lot and uses the ti gears to save his drivetrain, beyond that, just replace the chain every 700 miles. Me, i'll wear anything out, so I stick with the cheapo sram stuff for the everyday bike, xt prices are out of my league for a part that i'll need to replace every 2 or 3 months.

  6. #6
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    Quote Originally Posted by HillbillyBiker
    A buddy of mine swears by his xtr ti cogs... he wants all ti... he says they will "never" wear out. He runs big ring a lot and uses the ti gears to save his drivetrain, beyond that, just replace the chain every 700 miles. Me, i'll wear anything out, so I stick with the cheapo sram stuff for the everyday bike, xt prices are out of my league for a part that i'll need to replace every 2 or 3 months.
    I would have thought that big ring would give less torque than small ring, therefore causing less stress on the cogs?

    But apart from that, its consistent with my gut feeling + my understanding of Ti (which could be wrong) in that Ti is harder than steel. Am I correct, or waaay of mark?

  7. #7
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    Yeah, my buddy is a tig welder and knows metals, ti is harder and tougher, he was just telling me last week he has a thin sheet of ti, like 20 guage and it can't be bent by hand, whereas 20 guage steel can be easily bent... i don't know what the means regarding wear on bike parts but he uses the xtr for the ti rings, not because of weight but because they last much longer than normal rings.

    yeah, definately, the bigger the ring the less wear cause the load is spread out. Some guys I know will run 2 chainrings and adjust the chainline so they can run big-big combo for climbing.

  8. #8
    PCC
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    This article relates to bike frames but applies here as well, to a point.
    http://www.sheldonbrown.com/frame-materials.html

    How fast or slow a part wears is influenced by its hardness, measured in Rockwell ratings, not anything listed in the above article, unfortunately. Hardness can be changed by heat-treating the part or by annealing it (annealing softens the metal). Certain anodizing processes can harden certain alloys, too. I'm not sure how accurate this is but steel can be heat-treated to a higher Rockwell rating than titanium or hard anodized aluminum so it will have better wear characteristics. Titanium is next then aluminum.

    Titanium sprockets are for weight savings and that's it. Steel makes the longest wearing sprockets as long as the manufacturer heat-treats it correctly and uses a good quality alloy to begin with. The reason XTR cassettes are so expensive is that titanium is an expensive metal to process into a usable alloy then requires more effort to create a part with. In its softened state, titanium is harder than a quality steel in its softened state but the steel can be heat-treated to a higher hardness.

  9. #9
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    The level of hardness of both materials depends on how they are treated. However, Ti can NOT be heat treated to reach anywhere near the level of hardness of steel. Thats why titanium is useless for applications such as knife blades for example (not to be confused with Ti coating).

    The Ti cogs on an XTR cassette will NOT outlast the steel ones on an XT. They are softer. Anyone with such an idea needs to do some quick research understand they are waisting money if thats what they expect. XTR cassettes are meant to be lighter, thats it. The steel cogs also have a slightly better treatment that makes them smoother and quieter but this will not really affect durability. That said and putting it into perspective an XTR cassette with proper chain care can last for a few years with no problems. While the Ti cogs do wear down a little faster than the steel XT ones they will still last a almost as long under the right circumstances. Don't expect them to wear down in 4 months or anything like that. After all, chainrings are made off aluminium alloy and can last years with proper care.

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