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Old 08-04-08, 03:18 PM   #1
tlarwa
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DA 7700/XTR Road Combination - Need Confirmation

Hi,

I've read a ton of posts on this, and am so confused I just want to make sure I'm heading down the correct path. I just had a hip replacement, and am looking for some lower gearing on my Waterford 2200 so I can sit in the saddle longer while climbing. The Waterford folks have confirmed that the position of the front derailleur braze-on will prohibit the successful tuning of the DA 7700 front derailleur with a compact crank (which was my first thought), so I'm moving on to other ideas. It looks like my next option is a MTB rear derailleur with a 11-32 or 12-32 (or 34) rear cassette. This way I can use my existing DA brifters, front derailleur and Truvativ Rouleur 39/53 crankset, while gaining some lower gear options. I really don't want to go the triple route because of all the parts that I'd need to replace. I am running 9-speed DA, by the way.

So, if I want to stick with XTR (just to keep it "high end" with the DA stuff), which model # 9-speed rear dearilleur and cassette should I look for? And does the rear dearilleur need to be short, medium or long cage?

Thanks!

Tom
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Old 08-04-08, 03:38 PM   #2
Al1943
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It will work. A 12-34 will give you the lowest gearing for hill climbing, I don't see any reason for an 11 cog unless you plan to race down a steep hill. If you run a 53-39 chainring set and a 12-34 cassette you'll need a chainwrap capacity of 36 teeth (53-39) + (34-12) = 36. Shimano mountain rear derailleurs are available in either "top normal" or "low normal". Either will work very well. Road derailleurs are high normal so if you want the shift levers to work the same way as your road derailleur you'll want the high normal. Based on Shimano specs any of the XTR derailleurs will work. For a triple you would need the long cage. Some models seem to have some carbon fiber parts.
http://cycle.shimano-eu.com/catalog/...=1217887172313

You'll want the chain to be long enough to handle the big ring - big cog combination just in case you accidentally get cross-chained in that combination. so you may need to add a link or two.

Functionally the mountain derailleur and cassette will work perfectly on your road bike. The downside of running a mountain type cassette is the big ratio and cadence jumps when shifting (and a small weight penalty). This can be a problem when riding in a fast pace group where you're trying to match speeds with others and ideal cadence is critical.
I'm surprised that the derailleur can't be lowered enough for a compact crankset. Usually a braze-on type front derailleur can get down low enough for a 50t big ring. On my wife's bike I had to grind and file the slot low enough for a 49.

Al

Last edited by Al1943; 08-04-08 at 04:01 PM.
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Old 08-04-08, 03:52 PM   #3
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What you propose will work perfectly. I've done it on several of my bikes and my wife is running the same setup on hers for the last few years with no issues. You will need the long cage rear derailleur.

You can save a few dollars by using XT quality cassette and rear derailleur in place of the XTR components.
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Old 08-04-08, 06:03 PM   #4
tlarwa
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I'm surprised that the derailleur can't be lowered enough for a compact crankset. Usually a braze-on type front derailleur can get down low enough for a 50t big ring. On my wife's bike I had to grind and file the slot low enough for a 49.
Al
I was hoping it would work, as I'd like to try a compact crank, but the Waterford folks (who are very helpful, by the way) confirmed that it wouldn't with this statement (and I quote):

"That is correct. Your frame is set up for a 53t outer ring and the boss is set at 146mm. With the 50t compact ring, the boss will be centered at 140mm. Your current boss will run out of range as the minimum (inner) chain ring size at the 146mm location is a 50t."

So, it looks like the XT or XTR option is my next move. Hopefully my new hip will respond well and I'll get my former cycling strength back. If that happens and I start to ride in serious group rides again I'll just switch back to my current set-up.

With a 53/39 combo up front, which XT/XTR cassette configuration would have the closest spacing while still affording me some decntly low gears for climbing? 12-34 or 12-32?
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Old 08-04-08, 06:06 PM   #5
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Shimano mountain rear derailleurs are available in either "top normal" or "low normal". Either will work very well. Road derailleurs are high normal so if you want the shift levers to work the same way as your road derailleur you'll want the high normal. Al
Does "top normal" equate to "high normal"?
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Old 08-04-08, 07:59 PM   #6
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Does "top normal" equate to "high normal"?
Yes
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Old 08-04-08, 08:02 PM   #7
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With a 53/39 combo up front, which XT/XTR cassette configuration would have the closest spacing while still affording me some decntly low gears for climbing? 12-34 or 12-32?
12-32

The 34 would give you a lower gear, either will work for you.
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