Compact Cranks

<<Living in he Rockies, a compact is great.......gearing for you is the only important part.>>

I guess to get a gearing advantage over running a double 39-53 with a 12-27 cassette, at least as far as having both a lower low end and a higher high end is concerned, one needs to run a Sram 11-25 or 11-26 cassette in the rear with the compact 34-50 chain rings, correct? Last time I purchased a bike, when I was briefly considering compacts, I mistakenly thought I either had to go with a Shimano 11-23, and give up a little bit of low end compared to standard 39-53 with a 12-27, or go with a Shimano 12-25 cassette and give up high end compared to a standard 39-53 with a 12-27. Are a lot of you with compacts, such as the Rocky Mountain rider above, going with the Sram cassette alternatives? I live in the Rockies too. I think if I got a compact I would probably want to run a Sram 11-25 cassette.

Edit: I just noticed when I was searching to see whether Shimano was offering anything higher than a 23 cog with the 11 cog yet, that a lot of people have been building their own Shimano 11-25s to go with their compacts by switching out cogs in Shimano cassettes.

chainstay said:

<<Living in he Rockies, a compact is great.......gearing for you is the only important part.>>

I'm using a Shimano 11/23 cassette with an FSA 50/36 crank. I'd want to go lower if I were climbing Smuggler's Notch in Vermont or Mt. Washington, but most climbs in the Rockies are not hellishly steep, just sustained

oldbobcat said:

The main case for compact cranks is that you can get most of the lower ratios of a triple without the complications of the triple.

That is what I initially thought the point of a compact was too, but in your case, your compact's low gear only matches a fairly standard low gear on a fairly standard double---that is a 39-25 gear. Your lowest gear is actually slightly higher.

oldbobcat said:

I'm using a Shimano 11/23 cassette with an FSA 50/36 crank. I'd want to go lower if I were climbing Smuggler's Notch in Vermont or Mt. Washington, but most climbs in the Rockies are not hellishly steep, just sustained

I live near the Wasatch mountains and the Uintah mountains. I don't know whether or not I am doing climbs any steeper than you, but regardless, I use my low 39-27 gear fairly frequently on the steeper sections of some of the climbs around here. I also try to keep my cadence to at least 70 on climbs, while subscribing to that theory that faster cadence is easier on the knees. Regarding the top end, it is fairly easy to spin out my 53-12 on some of the descents here if I want to.

A compact 50/36 crank with a Sram 11-26 cassette sounds like it could be interesting to me because it gives a little bit lower gear than the 39-27 does, and it gives one little bit higher gear than the 53-12 does. JMO.

oldbobcat said:

I'm using a Shimano 11/23 cassette with an FSA 50/36 crank. I'd want to go lower if I were climbing Smuggler's Notch in Vermont or Mt. Washington, but most climbs in the Rockies are not hellishly steep, just sustained

What is hellish, 12 to 16% is a bit of hell for me and a lot of them around the rockies.

chainstay said:

That is what I initially thought the point of a compact was too, but in your case, your compact's low gear only matches a fairly standard low gear on a fairly standard double---that is a 39-25 gear. Your lowest gear is actually slightly higher.

I know, and I like it that way. I also like being able to single-step on the first eight cogs. I am not in any kind of competition to match low gears with anybody.

So has anyone on here tried, for example, a FSA 50/36 or 50/34 compact crank with Shimano Ultegra or Dura Ace derailleurs, Shimano chain and a Sram cassette? I wonder if all those different brands shift and work smoothly together?

chainstay said:

So has anyone on here tried, for example, a FSA 50/36 or 50/34 compact crank with Shimano Ultegra or Dura Ace derailleurs, Shimano chain and a Sram cassette? I wonder if all those different brands shift and work smoothly together?

Well I guess no one has tried a FSA 36/50 crankset, 36/50 Dura Ace, 36/50 Ultegra crankset or Sram 36/50 crankset with a Sram cassette, because near as I can tell, Campy is the only one of the big four crankset manufacturers offering cranksets in the 36-50 configuration.

chainstay said:

Well I guess no one has tried a FSA 36/50 crankset, 36/50 Dura Ace, 36/50 Ultegra crankset or Sram 36/50 crankset with a Sram cassette, because near as I can tell, Campy is the only one of the big four crankset manufacturers offering cranksets in the 36-50 configuration.

My FSA Gossamer (cheap) is 50/36.

chainstay said:

So has anyone on here tried, for example, a FSA 50/36 or 50/34 compact crank with Shimano Ultegra or Dura Ace derailleurs, Shimano chain and a Sram cassette? I wonder if all those different brands shift and work smoothly together?

i've got k-force in 50/36, though the 36 was not the off the shelf configuration. i run that with sram force, kmc chain and depending on the wheels either sram 1070 or ultegra cassettes. shifting is fine.

--brett

sideshow_bob said:

i've got k-force in 50/36, though the 36 was not the off the shelf configuration. i run that with sram force, kmc chain and depending on the wheels either sram 1070 or ultegra cassettes. shifting is fine.

Ok, thanks! I didn't see 36-50 cranks mentioned on the FSA website as a choice for their higher end cranksets, but now I see 36T is listed under their chainring offerings.

melslur said:

Tim's avatar is from a tv show. Note the 4th line in "Character Summary":
en.wikipedia.orgBubbles %28Trailer Park Boys character%29Open ↗

Just having fun.

That explains it! I don't get Canadian TV so I never got to see the show. I just thought that was a real picture of Tim😄 !

chainstay said:

So has anyone on here tried, for example, a FSA 50/36 or 50/34 compact crank with Shimano Ultegra or Dura Ace derailleurs, Shimano chain and a Sram cassette? I wonder if all those different brands shift and work smoothly together?

My Cervelo tri bike comes stock with an FSA crank (the SLK). When I bought the bike I wanted to swap out the crank for a compact. My LBS did not want to sell it to me with the FSA compact (34-50) due to shifting complaints they had with the bikes they had set up that way. This was mostly due to the braze on front deraileur mount (on Cervelos) being to high (even in it's lowest setting) to be close enough to the large chain ring for ideal shifting. Still with the shimano compact (and a spare set of pedals for the coast difference!) I haven't had any shifting problems. Another solution would have been a compact specific front deraileur.

Generally speaking, you can't go wrong if you stay within a brand but I think in most cases you're fine swapping brands for cranks & deraileurs. The deraileurs are "dumb" in that they just move the amount that the indexing on the shifter tells them to.

I have a good friend who just found the used bike (high end frame) that he is interested in, except that it is built up completely with Dura Ace 7800 double, and he is used to triple for the Rockies. The bike is such a good deal that I told him I thought he could buy the bike, then purchase a Shimano FC-R700 compact 50-34 crankset (I found a new one online for $176 USD), bolt it on to existing DA 7800 hollowtech bottom bracket, and then run the new Sram 1070 11-28 10 speed cassette in the back and achieve the same wide range of gears he previously had on his triple. However, now I am worried whether the standard DA 7800 double derailleur has the capacity for this and whether this combination, 50-34 with 11-28, can be expected to run smoothly. The bike has a clamp on derailleur, so there will be no problem adjusting the height of the front derailleur. Other than the wider gear jumps which some people don't like with wider spaced cogs on a cassette, does anyone see any problems with running this 50-34 crank 11-28 cassette combination?

Thanks for your answers! 🙂

That's along my line of thought too. If someone is thinking about ground clearance at those sort of lean angles they're thinking about hospital visits too!!:o

artemidorus said:

Why does a compact crankset give you less ground clearance? 😕

There is an alternative between compact and triples....I've got a 38 front and 27 on the back on my geared training bike and that gives me a 38 inch gear whereas a 36 / 25 gives a slightly higher gear than that. I run a 50 big c/ring so lowered my front derailleur to suit. Works well🙂

You could give that a try for less expense and minimal changeover🙂