Re: Shimano D/A RD-7700 for 10 spd?
Originally Posted by Lonnie Utah
That combination of teeth is out of specs. The total chain link uptake capacity for the 7800-ss (which I currently have) is 29. If I wanted to run a 12x27 rear cassette with the 50x34 compact double that I have it works out like this
50-34 = 16
27-12 = 15
16+15 = 31
With the longer cage derailluer the capcity goes up to 37 so it would work better.
From what I've been told here, there is no reason you can't run the short cage deraillure out of specs, but it is at your own risk. That's most likley what I'll do. Either that or sell the 10spd ultegra 12x27 and get a 12x25 instead, bringing the system into spec. But I didn't think that combination was THAT much more benificial that the 11x23 that's on there now, so why spend the money? Honestly I've cranked up some pretty steep stuff with the 34x23 (10% for more than 1 mile) and while my cadences have been low, it really hasn't been that much of a problem. It would just be nice to have a bail out option. Anybody want to buy a 10spd cassette with less that 5 miles on it?
Sorry, let me try this again ...
There is little reason that I can see why you can't swap the 11t pulley wheels in your 7800-SS rear derailleur with the 13t pulley wheels from your 7703-GS rear derailleur other than the psychological trauma a (temporarily) cannibalizing one to benefit the other ...
I think the 7703-GS cage is fractionally longer (is that right), so your increase in chain capacity will only be the 4t differential in the pulley wheels ... that gives you a theoretical capacity of 33t if you change both pulley wheels, and 31t if you only change the trailing/"lower" pulley wheel (see attachment
The particular pulley wheel (sorry the pic is so small) is from a cheap mega-
rear derailleur ... the particular 13t pulley wheel's bushings were too wide because it was for a 7-speed derailleur & it needed to be narrowed to fit the 950 cage, but the teeth were fine. I wanted to "test" fit the 13t pulley wheel before buying a 13t pulley wheel from a 7703 rear derailleur for the above pictured XTR rear derailleur ... but, it works so well, that I figure "why bother until it wears out?"
alternate anchoring SHOULD BE viable, and you have nothing to lose by trying it other than the time it takes to remove the 7800-SS rear derailleur from your bike and putting the 7703-GS rear derailleur on in its place.
If the rear derailleur cable is anchored as shown in the hubbub.com position, it will NOT slip ... at least MY limited experience is that should not be a concern.