Rear cassette ratio?

[volklpowdermaniac]

I have a 2005 trek oclv full carbon with full ultegra components. Love the bike. Just had a spring tune done and it looks like I will soon be in need of a rear deraiuler. It's currently a 2x9 but the new ultegra RD seem to be 10 speed only so ill need to change out the rear cassette as well. My plan is to do a new ultegra rd... A new ultegra cassette, new chain and new 10 speed rear shift lever. What gear ratio in the rear cassette do I want to go with my standard 53-39 ( I'd like to go compact double but with the rear parts wearing I have to hold off for now) so given that front config. What gear ratio in the back... I live in summit county Colorado so routinely riding swan mountain, vail pass, Hoosier, independence freemont but also all the flats in between... I don't know what others consider hilly but I like to think this is a reasonably hilly area.., thoughts?

[volklpowdermaniac]

I will ask, and this shows my mostly limited knowledge a) can you still find a new ultegra/dura ace 9 speed derailleur out there b) can you use a 10 speed deraileur on a 9 ring cassette... I only ask because it looks like the shifters might make this prohibitively expensive... So staying with a 9 ring cassette would be ideal

[reynolds.trailrun]

As far as I know, The 9spd and 10spd indexing for road rear derailleurs are the same unlike mtb. I have a used Ultegra RD 9/10 speed for cheap (Came off of a Trek 2200 that was a 9spd). Gave to me so $30 shipped (sound reasonable?) or $45 for RD + cassette (I can check the ratio when I get home tonight but think it is a 12-25)? Or you could just buy a new RD and still use your shifters with a new cassette/chain/chainrings. Still costly but saves a bit on the brifter (brake/shifter units).

To answer your first question, I would suggest 11-25 or 12-28 for cassette combination if you are looking for a wider range with a preferable gear for climbing. Or if you have a long/SGS RD you could use a mtb cassette for an even wider ratio like an 11-30 or 11-32. I am not all that much of a fan for the wide range feeling when shifting on the road. The huge jump feels great on the mtb. On the road I do not like it that much.

[TomCrac]

Depending on how big you want to go in the rear will impact the size of the rear deraileur. The larger the rear, the longer reach the rd will need to be able to suck up chain. Your lbs will know.

[smslavin]

What gear ratio in the back...

i run an 11-23 with a 53-39 up front. i don't have much difficulty getting up stuff. 25 might be nice if and when you hit stuff in the 12% range.

[jamal]

Do you know what's on there now?

I'm happy with my 11-25 cassette on a compact. I haven't ever needed an easier gear and since I've started riding with a cadence sensor I've stopped considering going to a standard crankset for now. Spinning faster is more efficient and you can generate more power. 100rpm in the 50x11 is like 38mph.

An new ultegra RD will accept a 28t rear cog, so I would go with either an 11-25 or 12-28 cassette, depending on how much climbing you do and how strong your legs are. 53x12 is shorter than 50x11 by a little bit, but I really don't find myself wishing for another gear. 11-28 would get you the full range but results in some pretty big gaps.

[volklpowdermaniac]

Thanks for all the info. The prohibitive cost here is the 10 speed shift levers... So I guess the question is will a new "10speed" ultegra deraileur work with a 9 speed cassette.. If so that would make this parts replacement a lot cheaper.... So far from my limited searching on teh webz it seems like it might

[XtrPickels]

Just go with an 11-28 (THey do not make a 12-28 ultegra).
Smslavin is a beast with that 23. Significantly more beastly than me anyway.

[jamal]

There's a 12-27 105 cassette, and sram does 12-26, 12-27, and 12-28.

But I am pretty sure you can use a 10-speed derailleur with 9-speed everything else. Here's an official shimano chart I found that seems to say so:
http://bike.shimano.com/publish/cont...ty%20Chart.pdf

[El Chupacabra]

Thanks for all the info. The prohibitive cost here is the 10 speed shift levers... So I guess the question is will a new "10speed" ultegra deraileur work with a 9 speed cassette.. If so that would make this parts replacement a lot cheaper.... So far from my limited searching on teh webz it seems like it might

Mrs. C. is using a 9-speed cassette on her road bike, which came with a 3x10 drivetrain -- we didn't swap anything else to use the 9-spd cassette, so the 10-spd rear shifter and derailleur seem to be fully compatible with a 9-spd cassette.

We did this so she could get really low gears for climbing: used a 12-32 SRAM mountain bike cassette.

[bigwaterbird]

There's a 12-27 105 cassette, and sram does 12-26, 12-27, and 12-28.

But I am pretty sure you can use a 10-speed derailleur with 9-speed everything else. Here's an official shimano chart I found that seems to say so:
http://bike.shimano.com/publish/cont...ty%20Chart.pdf

+1
I have used 9 and 10spd rear derailleurs interchangeably; it is the shifter that determines how far the derailleur travels each click, not the r.d. And as stated above, depending on your gearing you may need to step up to a GS (Medium Cage) rear derailleur.

[kidwoo]

If you want a brand new ultegra 11-25 cassette, let me know. I got it as part of a kit and it's not big enough for what I got it for.

Or trade for an 11-28........

[RShea]

As you have found out the switch to 10 speed shifter is more than most want to spend. Stay with the 9 speed cassette (last one I got was 11-23 last season- local shop had it in stock) but the 25 or 28 if you really think you will want a wider range and still think about going compact for the front. Much better use of funds than 10 speed upgrade. For the rear cassette if Shimano does not have the ratio that you think would be best, check SRAM. I was leaning toward SRAM until my shop stated they would have to order the one I wanted in 9 speed.

[L7]

I haven't read all this but I certainly think it's worth going compact with 10 speed. What sold me was realizing a 50 -11 is a bigger gear than a 53 - 12. I don't put an 11 on the 53 anymore so what's the point in staying with that. The compact gets rid of some overlap and gets you more gear on both ends with tighter shifts. 50 -34 and 11 -23 works great and I still have the 12 -25 for real steep stuff. The derailleur shouldn't matter as long as the cage is long enough. It's the shifters as far as 10 speed vs 9 and the chain.
I have a lightly used 9 speed cogset 11-23 I think and a moderately used 12-25 if you really want to stay with that.

[volklpowdermaniac]

I ended up with a new 10 speed rear derailuer. New 9 speed 12-27 cassette and new chain. Old derailuer was kaput. The new one however seems to be skipping a cog on its way down from biggest to smallest. It's skipping the second largest cog. Going from 27 directly to 23 or whatever. Brand new rear derailuer so one hopes its not bent , what else could be the culprit?

[reynolds.trailrun]

How long since cable/cable housing? If this is pretty old then it might be time for that. Try putting a thin layer of dry lube on the cable. If this helps significantly then you need new cable and cable housing.

[jamesp]

Aren't 9 speed & 10 speed different shifting ratios, ie der has to move different amounts to shift?