Of compact cranks and cassettes - another gearing conundrum
Calling all gearing/component gurus...
I ride a Cervelo that came with a standard 53/39 and 12-25, and it's served me just fine. The deraileurs are DA, the crank is FS-K and the cassette ultegra. I experimented with a 12-27 rear last year from SRAM, and despite the claim of compatibility, it really was just "almost" compatible. I had all kinds of minor troubles with it. I gave it up after never being able to adjust it so that I could both get into the 27 and not skip gears in the middle. I had a couple of good mechanics give it a go..not just me.
Now I'm considering going compact. I don't want to be ridiculously cheap, but I am trying to keep costs reasonable (whatever THAT means!). That probably means sticking with Shimano to assure compatibility with the rest of my drive train, unless you know of a better alternative.
I've looked at gearing, and what I think I'd like is 50/34 normal compacts in front with 11-25 in the rear. I do like to pedal downhill when I can, so I'd just as soon have the 50/11 as a top gear over the 50/12, which is obviously a (small) downgrade from what I have now at the top end. We have tons of rolling hills in my part of the world [midwest], so getting that speed down the top of the hill is kind of a big deal. So here are my questions:
- It looks like both R700 and the ultegra 6750 are compatible with my setup. The latter appears to be a $250 or so product, and the former appears to be only about $150, yet the online reviews I see say it's an older piece by only a couple years, and approximately the Ultegra level before there was an Ultegra compact. What gives? Is it cheap because it's been discontinued or am I misreading things? Is the R700 crap? Are these good choices in the first place?
- I'm annoyed that you have to buy 11-25 as DA, not ultegra. :-( I don't want to spend $300 on a cassette...
- The cheapest solution is - I think - not really a solution. I think you can buy a new 11-tooth ring and a compatible ringlock, but I gather that's not compatible with the 12-25 hub. Can someone confirm? I really don't think I'd have a problem missing my 12 in favor of the 11, since I use the 53/12 combination only when flying anyway, and usage of 53/13 is probably even more rare for me.
- Can I buy a "normal" ultegra 6600 11-23 cassette, and then cannibalize the two cassettes to give me the 11-25 that I want? I know the last few (largest) gears are a single piece, but can I reasonably use the 21-23-25 (or whatever it is) single piece and then choose whichever sequence I want after that if I use the 11 lockring and 11 smallest cog? (e.g., skipping the 12 or 16) That's still about a $75 solution, but a lot better than $250-300
Or am I just being a dope in the first place and just buy the compact front and don't worry about it?
Thanks for your wisdom!
Comments
http://www.slanecycles.com/bike-parts-bike-components-cassettes-c-6_123.html?page=3&sort=20a
Thanks for the tip. I hadn't seen the 6700 11-25 before anywhere. I should learn to look harder! I stand corrected completely on that point. It is available at a few sources I now find. I failed to search that part and just looked at a few suppliers that didn't happen to stock it. Thanks/sorry.
The other question, though, still stands - about R700 vs Ultegra cranks. :-)
BTW, the 6750 vs. 6700 is just telling you it's a compact (i.e., 50-tooth on the large ring) crank. The triples have numbers that end in 3 and the standard ones end in 00.
I can't speak to prices of cranks, differences between them, etc. But I think you should go with the 25-12 in Ultegra or whatever is cheaper vs the 25-11. I ran compact + 25-12 for years, in all kinds of riding conditions. You'll spin out (120+rpm @ about 39mph vs 42-43mph with the 11). That's plenty fast.
The 25-12 will have a tigher cadence ratio than the 25-11 and 98% of time you won't feel the need for the 11t. For me it's nice to have because I have long descents where I can wind it up to 45mph+ and I like to keep pedaling comfortably on these downhills when I'm above 36mph, just because. But these are long downhills, 3-16 miles, not a very common riding situation for most.
I also used a R700 for all of last season until I got my quarq this year. It's an awesome crank for the money, the only reason to go with the more expensive crank is weight, which means very little.
We do have local 35-48 mph hills, but they're not nearly as long as Rich describes: just steep rollers, etc...but I do feel better being able to engage the gearing for longer. I'm not trying to top 50. Well maybe once, just to say I did. :-)
I have had a couple rides on it here locally, and I've intentionally chosen to go out over the rolling-hilliest routes around here. (Sorry, no MOUNTAINS in my neighborhood). So far, I'm very pleased. A few observations:
1) As my season has progressed, my cadence has gone up anyway. So far, no issues with the 12-25 being too "low" a gear on the 12-side. Can easily pedal for long enough bursts into the upper 30s mph at 110-115 rpm
2) I love the gearing in the 18-25 mph range. I think I have one more functional gear in that range than I did before (with 53-39), and I can do a lot less big/small-ring switching... That is a surprising big benefit!
3) Sounds strange to brag how FEW watts I can use to climb the local hills, but that was the point, now, wasn't it..... Haven't stood up on the bike since it was installed. The one last challenge on that point (spinning easy up the hill) will have to wait until after my A-race (longest/steepest hill too far away for taper time).
4) Quality of shifting up front especially is noticeably improved. Not yet sure whether this is just from someone who knows what he's doing tuning everything up just right or actually from the new crank vs my old FSA, but either way, it's a nice benefit, especially before the big race.
5) Can't imagine ideal standard-to-compact adjustment time would be more than a couple weeks given my experience so far. I get one week, and I'm confident it'll be fine. It just works.
Again, Rich, great recommendation to go 50-34 and 25/12.
But addressing the cassette:
I kept looking at charts and wanted to go 11-25 (or 11-26), but I already had the 12-25 obviously, and I noticed a pretty big gap in the 20-22 mph range (90 rpm). This convinced me to give the 12-25 a chance for a while to see if I really needed the 11. (In effect you trade an 11 for one of the middle cogs going from 12-25 to 11-25.) I know I've only had this a few days, but so far I'm ok with losing the top end a little bit for the reasons I stated above.
This graphic tool is very helpful for visualizing where the gear gaps (and high and low end velocities) will be:
http://public.tableausoftware.com/views/bikegears/CompareBicycleGearing
It likely shifts better in the front as lots of people claim that the FSA cranks are not as good a quality as the ultegra ones. Assuming that you had the gossamer ones that cervelo specs on lots of bikes they are certainly less expensive than ultegras. That said it is more likely do to being adjusted better. I have used super cheap cranksets and never noticed any problems with shifting.
As for the cass - 50-11 is a taller gear than 53-12. As for big gaps in the cass I have never noticed the differences except on the really high and low ends when running 12/27 - 12/25 - 11/23 - 11/26 ... maybe I just do not pay enough attention but really does not seem to matter. I know that climbing with a 26 or 27 is a hell of a lot more fun than with a 23 though. Lately for non race day [and non whiteface stuff] I have been riding all the time with 11/23. Figure it goes with the hurt myself in training plan...
Last year, I mostly used a SRAM 12-27 cassette with my 53-39 and we (me and the LBS) could never get the drive-train really well adjusted...kept hesitating and/or jumping. Problem instantly solved (OK, 5 minutes....) when I went back to an ultegra cassette. This solution seems much better both in terms of shifting and gear coverage.