Thoughts on mid-compact cranks?

[sweet_johnny]

I'm in the process of upgrading my Zank from 10 (non-yaw) to 11 speed and am having an internal debate with myself about whether to ride a standard 53/39 or a mid-compact 52/36. I've been riding a 52/36 for a while and here are my general thoughts:
- I spend a vast majority of my time in the 52. It's not THAT hilly in the Boston area, so unless it's steep or I'm tapped, I'm in the big ring.
- The little ring feel really sloppy. I get chain rub against the big ring while in the 36 x 14 or 13 and the 36 x 12 is unridable (Admittedly, this could be from being mis-adjusted). I feel like I have a lot of chain slop at the 36 x 12 end and the chain is tight as hell at the 52 x 26 end.
- Shifts from the little ring to big ring are not very smooth.

I do realize that I could ride a 53/36 with a 11-28 and be at the same gear ratio, but there is something really nice about the tighter cluster of a 11-26.

What are other people's experiences? Did SRAM get it worked out with 11 speed?

[chiasticon]

<obligatory doesn't shift well because Sram something something remark>

I've been running force 22 with 52/36 and 11-28 out back for a year and it's shifted great, with no rubbing. all my bikes have been on the 22 yaw FD's for a few years now and they're way better than the earlier stuff. 52/36 is a great combo; I like 50/36 too, but I'm a spinner and don't race.

[stien]

My brother loved Red 10 with yaw, so I'd imagine 11 was even better or the same. He complains that 9000 has rub sometimes and misses his yaw.

I wouldn't generalize and say that all mid-comapact cranksets have rub and/or shifting issues. It's heavily groupset, chain length (tightness), and frame size dependent. We use them exclusively now and haven't had any of the issues you speak out. Then again we are running 11s Di2.

[Lovetoclimb]

I spent many years riding and racing in Cincinnati OH and Northern KY on a 53/39 & 12/27 Campy setup. Some good 3-5 minute climbs around there with some seriously steep pitches scattered about but my youthful exuberance and joints were always up for it. After a year of living in Asheville and the proper mountains I switched to a 52/36 up front and was in awe that I could sit down on 20 minute climbs if I wanted. On the heavier of my 2 road bikes I finally switched to a full compact up front and was even happier. Of course over time I have gotten substantially slower because I now have increasingly easier gears at my disposal but since I no longer care who I am keeping up with it doesn't really matter. Having set up a few SRAM 22 drivetrains it has been my experience that no matter what the extreme ends of the gear spectrum rub on the yaw FD. Maybe because there is no true trim position on either front ring, or because I don't know what I am doing, or because SRAM engineers are a bunch of hacks, but Shimano and Campy both nailed the mid compact drivetrain regardless of cassette size in the rear.

If you're intent on sticking with SRAM you may consider the 53/39 up front and 28t or even 32t in the rear. I have had people visit that throw a 32t max cassette on and can sit and spin up some vicious grades in their 39t chainring with that range.

I really wish SRAM would use some of their tech budget to make a series of mechanics oriented videos like the Shimano STEC program. Especially with the Etap program rolling out to shops.

[shovelhd]

I'm in the process of switching from a 53/39 to a 52/36. If I don't like it then I can always go full compact. This is on 9070 Di2.

[eBAUMANN]

50/34 is terrible, for me, riding around NE, its just bad.

52/36 is great. 52 is big enough to go fast, 36 is small enough for when you need it.

53/39 is also great. just gotta have the legs to push it.

32t has no place on a road bike. Unless you are over 50 y/o or 220lbs. Then its acceptable.


As far as rub goes, no reason to be riding 36/11...once its start rubbing, its time to upshift. this is called cross-chaining, it is frowned upon. :no:

If you shifting is bad and not smooth, its probably because you are riding SRAM. If you arent riding SRAM, your bike needs a tune up.

[batman1425]

Sram Yaw eliminated FD rub, but the chain will still rub on the inside of the big ring when cross chaining. The amount depends on your frame geometry, chainstay length, etc.

But, as Eric said, if you hear that, it's time to shift up.

[benb]

50/34 is terrible, for me, riding around NE, its just bad.

52/36 is great. 52 is big enough to go fast, 36 is small enough for when you need it.

53/39 is also great. just gotta have the legs to push it.



Pretty much agree with all this living in the same place. There is a little more to my opinion though.

Right now I just swap wheels on my All City Space Horse for different applications. I keep one set for wheels with off road capability and one set for go-faster stuff. The off-road wheelset I have a 11-30 cassette on. The on-road one I have a 12-25.

What I have found is that the 12-25 is really annoying with the 50/34. You very frequently find yourself hitting hills and if they're bigger or you're tired all of a sudden you are spending a lot of time in 50x21 or 50x23. Or if you use the small ring you're finding yourself in 34x13 or 34x12 a lot.

Then when you need to shift down all of a sudden you need to switch rings.. but because the gap between 50 & 34 is so big you need to change 3-4 cogs as well to get to the right gear (because it's a tightly spaced cassette). It makes it quite challenging to perform the whole shift quickly and smoothly. It doesn't help if you have 10-speed shimano shifters that only shift 2 cogs at a time too!

Meanwhile with the 11-30 cassette I just bang up all those hills in the big ring no problem, 50x28 gets me up a lot of hill, and I don't find myself often hanging out in the zone between the 2 rings, and even if you are, a 2-cog shift on an 11-30 often is a 4-tooth jump so you can bang out the ring + cog change quickly and smootly. Meanhwile the 34 is sufficiently low for off-road duties, carrying a load, or pulling a trailer.

Then you go to a fast bike and 53/39 just rocks because you're on a closely spaced cassette but the rings are closer together so you can rapidly change the rings + cogs at the same time, you get the best of both worlds. Ironically on a light/fast road bike there are lots of hills around here I feel like I can go up just fine in a 53x23 that I would have trouble getting up in the 50x23 on the Space Horse since it weighs 25lbs.

[Mark McM]

50/34 is terrible, for me, riding around NE, its just bad.

52/36 is great. 52 is big enough to go fast, 36 is small enough for when you need it.

53/39 is also great. just gotta have the legs to push it.

32t has no place on a road bike. Unless you are over 50 y/o or 220lbs. Then its acceptable.


As far as rub goes, no reason to be riding 36/11...once its start rubbing, its time to upshift. this is called cross-chaining, it is frowned upon. :no:

If you shifting is bad and not smooth, its probably because you are riding SRAM. If you arent riding SRAM, your bike needs a tune up.

Comments about chainring sizes are meaningless without specifying rear sprocket sizes.


But I'll add my own comments. Many times switching to compact cranks is actually changing the wrong end of the drivetrain. It is usually better to first look at changing the cassette before changing the crank, for several reasons.

As an example, I had a friend who's bike had a 53/39 crank and an 11/23 cassette. He felt that he didn't need a gear as high as a 53-11, but wanted a lower gear than a 39-23, so he was interested in replacing his standard size crank with a 50/36 compact crank. It was pointed out that he could get the same gearing range the for less money by simply replacing his cassette with a 12/25, which would also give about the same step sizes between gears. He was unconvinced - compact cranks were New! and Improved!, so they must be better. It was further pointed out that the larger cassette would also be more efficient* and be more durable** than the compact setup. But facts didn't sway him, because all the bike magazines were raving about how fantastical compact cranks were, and he ended up spending a chunk of change for new cranks/chainrings, plus a new bottom bracket since his old BB wasn't compatible with the new cranks.

Despite my friend's follies, it is better to first optimize the rear cassette (based on gear step sizes and derailleur capacity), and then think about the appropriate chainring sizes.

*It has been shown by several tests that larger sprockets are more efficient than smaller sprocket, for the same power, so a drivetrain that utilizes a larger sprocket/chainring for the same ratio will have less energy loss. The increase in efficiency more than compensates for the slight weight gain.

**It has also been demonstrated that larger sprockets/chainrings wear more slowly than smaller sprockets/chainrings, plus the lower chain forces will also result in slower chain wear.

[sparky33]

Did SRAM get it worked out with 11 speed?

I cannot add anything to the sensible comments here on gearing, but I can say that SRAM 11 speed works well. I could ride all 22 ratios without any fuss, and the levers are nice to work with. The price points are very good too.

I have 2 Red22 bikes and a CX1 11 speed.

[FastforaSlowGuy]

Remember that chain rub is partly a matter of CS length. Tolerances get tighter as the CS gets shorter.

One of the reasons I like the new 4 arm cranks is the ability to easily swap chainrings.


Sent from my iPhone using Tapatalk