shydroxide

I'm looking to buy a cyclocross bike as my first real bike after a long period of not riding... more than 10 years (I'm 28 now).

I've spent the last year getting into shape (went from 270-160 lbs. by eating less and hiking, running and lifting) and I'm interested in riding for fitness, to see more of the area I live in (the Okanagan valley in British Columbia, Canada) and to participate in cyclocross racing (which to me seems like a mix of a bike race and something like Tough Mudder, which I loved when I did it in September). Terrain here is a mix of flats and long hills, but I also want to ride trails and some offroad (nothing seriously gnarly). For this reason and because I'm not drowning in cash, it seems like a CX bike is the best choice as it should be versatile enough to do most of what I want to do with it. I don't at the moment plan to do any serious road racing or participate in a triathlon.

That being said, one of the things I've found is that most CX bikes that are positioned more for the "commuter" have 50/34 cranks, and those that are more "race" oriented have 46/36 cranks. On the face of it it seems like the compact crank would be more versatile as, given an identical cassette paired with each, the compact provides a higher top gear and a lower bottom gear.

That being said, it limits my bike choice quite a bit (unless I want to immediately replace the crankset or chainrings upon purchase) as more than half of the bikes in my price range (<$1500CAD) ship with a 46/36.

In general, do most semi-fit cyclists find that 46x11 is insufficiently high for road riding on flats? I can see where you would be able to spin out on a steep downhill but I'm not as worried about that. It is also my understanding that the 50 is too big to be of any use in an actual CX race, but couldn't I just stay in the 34 for the whole race or would that be too low to be competitive?

DirtRoadRunner

You won't spin out a 46x11 until over 30 mph - so it really isn't an issue on flats, but can be an issue on long descents. I personally think a 46t big ring is perfect for a general mixed-purpose riding bike. It isn't ideal for 100% road riding, but works well if you plan to ride a mix of road, singletrack, and gravel.

For the little ring, a 36t may be great for CX racing, but is actually a bit high for hilly riding or singletrack - if you get a bike with a 46-36 crankset, I recommend swapping the little ring out for a 34t to get just a little more low gear for off-road or long climbs (a 34t ring is the smallest you can fit on a 110 bcd compact road rank).

shydroxide

Thanks very much!

Alias530

46/36 is ********, gap is too small

46/34 with 11-32 or 11-28 would be better

Alias530

Actually 33 is the smallest for 110bcd but it's uncommonly made

gregf83 

46/36 will be fine. You'll never spin out on a steep hill as you just need to get up to a decent speed an coast. The only potential problem would be if you were on a slight descent with a tailwind where you could reach a high speed while still pedaling but those conditions are rare and it's a moot point if you aren't racing or riding with a fast group.

I commute on a 1x10 setup with a 42 front ring and a 12/26 on the back. It can be a little tough on a slight downhill with a fast group but as I mentioned those conditions are rare. My crank recently broke and I bought a replacement 46/36 so I think I'll add a front derailleur and have a wider range.

nfmisso

+1, and maybe 11-36 cassette to give you the lower gears. The 11-36 may drive you to a different RD, which is somewhat problematic with Shimano 11 speed road shifters, for Shimano 10 speed road shifters, you can use a Shimano MTB 9 speed RD such as a M592. SRAM is easier.

gamby

46/34. Best of both worlds. Seriously.

unterhausen

46/34 means you have to buy a chainring. I wish 44/34 cranks were available, but I guess that the racers want those 2 teeth in the front

DirtRoadRunner

Chainrings aren't too expensive - I bought a FSA 34t ProRoad ring for $30 new. A few weeks later, I saw someone selling a slightly used one for $5 at a swap meet. They are also very easy to install - 15 minute job tops, with the only special tool being a chainring nut wrench.

Kopsis

500W in the flats with no wind will get you to roughly 30 MPH. A 46/11 at 110 RPM is about 37 MPH, so a beginner shouldn't really have to worry about spinning out. For actual CX racing, the 36/46 is popular because it works well on a wide range of courses. Are there better setups for specific types of courses or mixed CX/road use? Yes, but as a beginner you really don't need to worry about that. Pick the bike based on fit and feel and don't worry about the crankset. You can get by just fine with either a CX or Road Compact for now. It will take at least a season of riding before your ability reaches the point where you need to start optimizing things like gearing.

Kopsis

That's what I thought when I first saw it. And though those elements do exist, there is a huge skill component that isn't obvious to the casual observer. No amount of brute force will help you keep the bike upright navigating a sandy or muddy off-camber turn. Likewise, mounts/dismounts and barriers require achieving a high level of finesse while operating deep into VO2 max territory. It's a huge amount of fun and I highly recommend it, but if you're going to try it, skill training will be far more beneficial than having the perfect gearing.

justin1138

i've had my cross bike for about 1 1/2 years now (would still consider myself fairly green) and the 46/36 has been fine. for everything. as a newbie, i don't think i would have noticed the difference if my bike came with different chainrings.

GravelGuy

For all around riding I'm in the 46-34 camp.

For a long time I was riding 50-34 but found (or felt) that I was spending a lot of time in the 50 and working the larger rear cogs for my general riding. By switching to the 46 I spend more time in the middle and smaller sized cogs, which for some strange reason makes me more comfortable. And I have no worry about spinning out a 46-11 unless I'm in some sort of free fall.

fietsbob 

The 46-36 is a Cyclo-cross gear , the 50 34 is a road 'compact double' gear .. now with 12 t cassette cogs either will be high enough.

get one set and get 2 extra chainrings for the other ..

RR3

I have both a 46-34 and 50-34 setup for long distance endurance riding. I hate the 50-34 because it usually requires a double shift whereas the 46-34 has more flexibility. Dropping off the big ring onto the smaller ring is usually perfect with the 46-34. If I want to stay in the big ring, 46x25 is a fairly usuable climbing gear. I sometimes wish for more top end but rarely.

Darth Lefty 

Gearing threads are fun!

46-36 makes a nearly perfect 2-step shift with an 8x11-28 cassette. One front trigger = 2 rear push, one front push = 2 rear trigger. Both triggers = one rear push, both push = one rear trigger. Added speeds to the cassette are to the top/small end. The middle and low/large end, where you do that double shift, stays the same. This is about the same story as the middle & top rings of a MTB or hybrid.

50-34 gives you 3-step gearing and a wider range, esp at the top. Do you need a wider top range? The top gear on a C&V 10-speed is around 52/14. You need a pretty steep slope or strong sprint to top it out. I guess pros sprint in 53/11.

ThermionicScott 

+1 to this. A 50/34 crank and 11-X cassette would have mortals like me cross-chaining the vast majority of the time. Since weeding out gears over 100" on my bikes (through shrinking the big ring and/or switching to cassettes with bigger starting cogs), I've been a much happier rider, and never miss those super-high gears.

A 46/34 makes far more sense for recreational riders than a 50/34, to say nothing of a 53/39...

Andy_K 

Another vote for 46-34. It's a great combination.

winston63 

Interesting and timely discussion! I've currently got a CX bike with a 46-36 and I've just decided to go to a 34 chainring to give me a little lower gearing for all round riding. I admit I rarely want more on the top end, but 36/25 is a bit tough on some of the hills I face.

grolby

Good grief. We're talking about a 2-tooth difference at the bottom end and 4 at the top. The latter will be noticeable, the former won't make a big difference. Everyone here is WAY over-thinking this.

What you should do is get the bike you like best. Completely ignore which crankset it has. The difference is small, and if you want to change it later, a 50/34 and 46/36 stock crankset will each accept the same chainrings. But just get a bike that appeals to you. If the gearing isn't low enough, get a bigger cassette. These are close enough together that for general riding you really shouldn't even be considering it.

Andy_K 

"If you want even the nerds to consider you a nerd, try getting enthusiastic about bicycle gearing." -Ken Kifer

I agree that you shouldn't choose a bike based on which crankset it comes with, but having the right gearing options can make a big difference in your bike riding experience. Also, all else being equal, it's cheaper to convert a 46-36 to 46-34 than it is to convert a 50-34 to 46-34. And since we have reach near consensus () that 46-34 is the way to go, that's worth considering.

As noted early and often in this thread, shifting from 34 to 50 and vice versa is awkward and inconvenient. Other than shifting, the only difference I notice between a 50T big ring and a 46T big ring is that I have more cogs that I never use with the 50T ring.

As for the low end, the difference between 36-whatever and 34-whatever is somewhat small, but when you need a lower gear you really need it. Someone on bikeforums once observed that any time you need a 34T ring you almost always really need a 30T ring. I agree with that, which is why most of my bikes have triples. My primary gravel bike is also my primary CX race bike, so it's the only bike in my fleet other than the singlespeed that doesn't have a triple (because triples suck for racing). Instead it has the afore-lauded 46-34 double. I recently took it out for a particularly hilly gravel grind, so it currently has a 13-30 cassette. (FWIW, more teeth on you big cog makes more difference than few teeth on your small chainring.)

DirtRoadRunner

Agreed - when you are going up a 25% grade on loose gravel, near the end of a long ride, every tooth counts. It can be the difference between walking (3 mph) or staying on the bike (5 mph).

FWIW, I've been loving my Sugino OX801D with a 46/30 combo. I rode some gravel this weekend with some guys on traditional CX gearing (46/36 up front and a 12-25 in the back), and I was happily spinning up steep hills, seated, while they were having to get out of the saddle just to keep going in their lowest gear. Unfortunately, a 46/30 crankset is hard to come by, but I did previously ride a 46/34 for several years and found it acceptable for all but the steepest of hills. We have lots of really steep, albeit short (100-300 ft high) hills around here, so the 46/30 provided to be a worthwhile upgrade for me.

grolby

I am not disagreeing with anything you have to say here, but we're talking about a first major bike purchase for someone, here. Not only do we not really know how the OP will be riding this and what their needs are, THEY probably don't know either. Maybe he/she will be riding in the big ring all the time and 50T feels great. Maybe they'll have to switch back and forth between the big and small rings a lot. I don't know. No one here does. The options being presented here are all but functionally identical if you don't have a basis of experience to choose between them.

Andy_K 

Now you've done it.... That's a new component at the top of my wish list!

I've been looking at mountain compact doubles for a while now, trying unsuccessfully to convince myself that the chainline would be tolerable. That Sugino fixes the problem.

I've got a 50-39-30 triple on my commuter, but 99% of the time I ride it like a 39-30 double. I spend most of my time in the 39T ring, but the hill at the end of my commute is 15-20% and so the 30T is barely low enough. Once in a while I'll take the scenic route and get a long enough stretch of road that I'm spinning out the middle ring and need a little more. A 46-30 double could be just what I "need". My touring bike has a 44-36-26 triple, which is a fun novelty, but more than a little pointless weight.