# Dura-ace 7900 10 Speed Cassette 11-28



## Nickbar (Dec 22, 2009)

Hi there

Where can I purchase the above at under $200?


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## Clevor (Sep 8, 2005)

Nickbar said:


> Hi there
> 
> Where can I purchase the above at under $200?


Try ChainReactionCyles. Last I saw DA 7900 cassettes were going for $150-160 price range, but to get the free freight you have to purchase at least around $240.

You ARE aware the Ti cogs wear faster than steel cogs?


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## Nickbar (Dec 22, 2009)

*Dura Ace Cassettes*

You have lost me?

Please explain what you mean by Ti cogs been faster?


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## DaveT (Feb 12, 2004)

Nickbar said:


> You have lost me?
> 
> Please explain what you mean by Ti cogs been faster?


The last four (the four biggest) cogs on the Dura Ace cassette are made from titanium. Ti cogs are lighter than steel cogs but will wear faster, sort of a 'race-day' cassette. Kind of makes them somewhat impractical for everyday, all-weather use in some folks eyes. You may be better served by using the same sized cassette in the Ultegra 6700 level, you can find those for around $70~$80 easily. The weight difference between the 7900 and 6700 cassette is about 2 ounces (56 grams).


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## Nickbar (Dec 22, 2009)

Thanks, but i was under the impression that Titanium was harder than Steel?

But as it happens i have since bought a Sram steel cassette due to price difference, and if it's harder, that will be a bonus.


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## Clevor (Sep 8, 2005)

I have a Dura Ace 7800 12-25 and weight is 189 gms. The same cassette in Ultegra 6600 is around 237 gms, so maybe 48 gms difference here. If you do a lot of climbing, you'd like to minimize bike weight but then again, you will probably be spending a lot of time in those four Ti cogs , so to me, it's not worth it from the standpoint of wear.


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## Clevor (Sep 8, 2005)

Nickbar said:


> Thanks, but i was under the impression that Titanium was harder than Steel?
> 
> But as it happens i have since bought a Sram steel cassette due to price difference, and if it's harder, that will be a bonus.


There is a misconception about titanium. I've dealth with it in regards to automotive racing applications, e.g., Ti valves and connecting rods. It isn't all that much lighter than aluminum, but of course aluminum is softer than steel. Ti is prone to galling. I don't think you can heat treat it as you can do steel, so you can make steel 'harder'.

I have one Ti bike. It's great for bike frames since you don't need to paint it, it hardly scratches, and it has a maintenance free finish. You can accidentally nick the frame with the end of an Allen wrench (how many times have that happened to us on carbon fiber frames!), or drop a chain repeatedly and it has no affect on the Teflon-like surface.


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## asad137 (Jul 29, 2009)

Clevor said:


> There is a misconception about titanium. I've dealth with it in regards to automotive racing applications, e.g., Ti valves and connecting rods. It isn't all that much lighter than aluminum, but of course aluminum is softer than steel.


Actually titanium is heavier (denser) than aluminum.

And a lot of people confuse (tensile) strength with hardness. They're independent properties.

Asad


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