Different Ways Of Crankin'

Is "Super Compact" the future for adventure/gravel bikes?

I am in the midst of considering parts for my build of the forthcoming Black Mountain Cycles MCD frame and fork. So far I have wheels lined up, through axles, a head set in mind, and now I am considering crank sets and bottom brackets.

That link above takes you to the frame tech page for the MCD and there will see that the maximum chain ring configuration is 46T/36T, or a standard CX crank set ring combination. This is what Ive used most often and what I will likely do again. However; if you haven't noticed, there is a move afoot to bring radically different gearing to gravel and adventure bikes, spearheaded by FSA, who provides a LOT of OEM parts to builders.

Their idea is called "Super Compact" and it is wide range double chain ring set up. I know a lot of you think 1X is the solution, but a LOT of riders don't like it. Too big a jump between gears, for one thing, but there is more to it than that. However; I am not delving into that subject just yet.......

Super Compact gearing is kind of like what the old randonneuring gearing was like. Basically you have a "drive" gear, (outer chain ring) which you use more often. The inner ring, the "bail out gear" or "grannygear", was used on steep climbs or when there was a tough headwind or like circumstances where a low gear was desirable. The modern form of this gearing utilizes wide range rear cassettes to keep jumps between gears closer and more efficient.

I tried such a set up on the old Gen I Fargo, using a 48T outer and a 28T granny, if memory serves. Modern Super Compacts wouldn't have that much disparity between chain rings, but it is close. FSA is pushing 48T/32T or 46T/30 as options I could use. My experiences with this sort of gearing wasn't positive. Oh, it's just fine when you are in the big ring, but when you dump out to that smaller inner ring your cadence goes haywire and I, at least, lost a ton of momentum when I switched gears. As a "native single speeder", I loathe losing momentum. So, that was a big reason I bailed on that experiment with that gearing.

New Ultegra CX crank set

This is why I am seriously leaning toward going to traditional cyclo cross gearing, which is 46T/36T. I like to use an 11T-36T cassette with that gearing, and I have a few reasons why I really have gravitated toward this gearing. Of course, the minimal jump between chain rings helps preserve momentum, which you probably already guessed.

The other reason that is important to me is probably pretty weird. I admit to a bit of a "Princess and the Pea" syndrome here, so bear with me on this one. See, I have very often been riding and thought, "Dang! This gear feels awesome today!" I can feel more power and just a more efficient pedal stroke many times in certain gear combinations, and probably 99.9% of the time when I bother to check, I have a dead straight chain line.

You may think, "So what?", and I get that, but a straight chain line is the most efficient one to pedal in. This is maybe something I tuned in to from my single speed days, but cross chaining makes me feel like I am working harder, many times. Not always. But every time I feel awesome about a gear, it is a straight chain line. So, I don't like the thought of running a "drive gear" and a "bail out gear". When the chain starts climbing the cassette, I like to switch to an inner chain ring and not jack my cadence up way over 100/minute when doing so. Obviously, I also can keep the chain straighter.

Now, some of you may be thinking, "Aha! We should still be riding triple chain ring cranks!" I would partially agree with that. In fact, I set my Badger custom bike up with a triple. That said, these newer gravel bikes, by their nature, are trying to also give us the shortest chain stays, (not really that necessary) with the widest tire clearances with an eye toward 650B mtb width tires. (Again- not all that necessary) So, triple cranks are a non-starter there.

I know that I could maintain a straighter chain line with a triple, but to some degree, the narrower chain rings and cogs we run now in combination with the best materials technology cyclists have ever enjoyed make a triple crank not quite the "no-brainer" that it used to be.

I haven't gotten back to that 1X commentary yet, but I'll save it for another day. Suffice it to say that since both SRAM and Shimano have filed patents and are working on chain sets that adjust for chain line misalignment inherent in 1X set ups, you can bet that your 1X system has too many inefficiencies. Otherwise, why would they bother? 

Stay tuned.........................