Equinox

I have a DA 7800 12-27 10sp cassett that needs replacing. I see they have a cs7900 10sp 11-27 cassette. Would a lot of adjustment be necessary if I put that one on? Will my existing chain be OK, because it is new?
Thank you

joejack951

You shouldn't need to make any derailler adjustments to run the 11-27. Your chain should not have the be adjusted unless it was sized for the small/small combo with no room for error. You can quickly determine if you'll need to shorten your chain by installing the cassette and shifting into the small/small combo. If the chain is still tensioned by the derailler and the upper jockey wheel is not touching the chain, you are fine.

As a side note, there's no reason that you have to use a Dura Ace cassette to replace your old Dura Ace cassette. Ultegra or 105 will work just as well with a slight weight penalty. For the price of a DA7900 cassette, you can buy 2 or 3 Ultegra or 105 cassettes.

Equinox

Joejack:
Thank you. I think I'll look into those other cassettes.

Garfield Cat

Equinox, I tried 11-28 Ultegra on my Dura Ace 7800, with a new chain. Works well.

joejack951

I just installed the same Ultegra 6700 cassette on a friend's DA7800 bike this weekend. No problems at all.

HillRider

+1 on the Ultegra or 105 cassette. You should be able to find a 12x27 in either model if you want to stay with that range.

There is a very small weight penalty but the cost of either cassette is much lower than Dura Ace, there is no performance or shifting penalty and the larger cogs are more durable since they are steel instead of Ti. Unless weight (or snob appeal) is your overiding concern, either Ultegra or 105 is a more sensible choice.

joejack951

This is currently one of the best deals going for an Ultegra 6700 cassette (especially with the extra 10% off coupon and team points): https://www.performancebike.com/bikes...0_20000_400189

Shimano seems to have dropped the 12/27 option for Ultegra 6700 though so if you want that combo in non-DA, you'll need to find a 105 or Ultegra 6600 cassette, or use SRAM.

HillRider

OT: [rant]What is with this insistance on 11T small cogs on road bikes? How many riders, even fairly strong ones, using typical road cranks (50, 52 or 53T big chainrings) can make any use of the 122 to 130 gear-inch high gear they produce? Using a 12T is a reach for most. An 11T on a MTB with a 42 or 44T big chainring may make some sense but not on a road bike unless you are National Team or ProTour material.[/rant]

joejack951

There is another use for those little cogs which is extension of the top end range of the inner ring (or middle ring on a triple). Especially with the changeover from 42 to 39T inner/middle rings in the past few years (and the compact double), those desiring to stay in one ring for most of their cycling have either needed to learn to spin faster or use smaller little cogs. I'm a holdout using 42T middle rings to avoid the hassles of quick wearing 11T cogs that I'd otherwise want.

HillRider

That's another thing, why the insistance on staying in the middle or inner ring for so much riding? A 39/11 is 95.7 gear-inches and a 53x15 is 95.4 gear-inches so why not use the 53/15 and be easier on the drivetrain?

A 39/11 combination is the worst kind of cross chaining, the very thing we warn so many riders against?

Al1943

I think a 12-27 would be the better choice. That would give you the 16 in the middle and closer ratios on the top end.

joejack951

A cassette starting with an 11T means that each of the first few cogs is 1 tooth smaller than a comparable cassette starting with a 12T. So at the same level of cross-chaining, you get a higher gear using a cassette starting with an 11T even if you never use the inner/middle ring with the 11T (for a small trade off in spacing of the big cogs).

Equinox

So I put the 11-28 Ultegra cassette on. No problems at all. I do notice a little more chain noise than with the dura-ace cassette. Do you think that will subside after break in?

HillRider

There shouldn't be any more noise. Changing cassettes often requires minor limit screw and/or cable tension adjustments to compensate for small position differences. Also, be sure the b-screw is set far enought in to keep the derailleur's jockey pulley clear of the 28T cog.

Equinox

So I'm enjoying m new cassette, except for one problem. the shift to one of the cogs is balky. It is the 13 toothed cog. All the othert shifts seem fine. I did not have a torque wrench, so I really cranked the lock ring. Could I have over-tightened it?

Al1943

Are you having trouble shifting from the 11 to the 13 or from the 14 to the 13?
You may need to add or reduce shift cable tension.

Equinox

It is from 14 to 13, I've played with the barrel adjuster, and every other shift is good. why just the one shift?