What are the differences (and their practical implications) between a 29" mountain bike and a cyclocross bicycle?

Question

I am considering the purchase of a bicycle for riding off road, and have heard a lot of buzz about 29" mountain bikes. However, I am not particularly interested in technical riding - although I would like to be able to ride through most things, even if I have to do so slowly.

I am leaning to a CX bike because I am familiar with the handle bars and geometry. However, the 29" also ride very smoothly. I can see that the tires, handlebars, suspension, and geometry are different, but what are the consequences of these differences that I need to consider?

Mountain Bike:

Cyclocross Bike:

Answer 1

There are a few very good answers on here already, however, I feel that a few pointers have been overlooked.

Height

I am not sure whether 29-ers suit all riders. Height comes into it, a 29-er imposes a high handlebar and heavier wheels than a 26" MTB. IMHO you need to be 6" or taller for the big wheel to make sense.

Standover height

The distance between you and the top tube is important on a MTB, regardless of your skill level. Most MTB's have a 'compact geometry' with big seat-post. Out the saddle it is useful to not have a 'five bar gate' between your legs, so, if you do go for the MTB, err on the smaller rather than the larger frame. You don't get this with CX bikes as a rule, although I would not be surprised if Giant do make one.

Brakes

Most 29-ers (if not all) come with disc brakes. CX bikes can come with discs but that is the exception rather than the rule. Disc brakes give much better stopping power, with little need for the rims to clean first. This gives you much better control.

History

Cyclo-cross pre-dates MTB-ing by some decades and the bikes for the sport evolved from road bikes. Meanwhile, the MTB evolved from a few Californians wanting to have fun, any notion of competition came along later. They were not tied down by UCI rules and UCI rules have always served to hinder rather than advance bicycle design. CX bikes are essentially a legacy product, for a 'formula' sport, not 'pure evolution'. They were not that popular before the mountain biking boom and have not been subsequently. Meanwhile, the separately evolved MTB is the 'weapon of choice' for many, many cyclists and CX ideas such as drop bars have not lasted long on MTB's (they have been tried by Johnny Tomac and Specialized did make a 'Rock-Combo' model with them, this was short lived). Wisdom of the crowds is that the MTB rocks off-road.

Suspension

For a long time I thought Suspension was a solution looking for a problem. However, there is suspension and there is suspension. A full suspension top end bike by the likes of Cannondale is amazing off road, you can roll over anything without losing speed or control. Cheap suspension is no good at all, i.e. the effort you get on a £300 MTB, perhaps useful for going up a kerb but that is about it. Modern, expensive full-suspension bikes are ridiculously light for how much is going on and a delight to ride. Well worth the investment, unless you are going XC with a bit of road to get to the trail in which case a hard-tail with front lockout is better for the ride as a whole.

Other uses

If you are a road-bike person then you probably carry nothing. Sometimes it is useful to have a bike you can carry stuff with. An MTB is really well suited to putting a rack on the back and carrying stuff. That may be just a trip to the shops or a long distance tour. Whatever your choice - CX or MTB, do look for those magical eyelets on the rear dropout for putting a rack on there. It may not be what you want to do now, but down the line it just might well be.

Answer 2

With a mountain bike (26" or 29") you've got

Suspension: basically, suspension lets you get into more trouble. There's terrain you'd need to bail on (or crash on) without it.

Flat bars: Beneficial for two things (IMO)—maneuvering and lifting the front wheel to clear obstacles. Wider bars give more leverage, which may be useful on, say, a very rocky trail, and will attenuate small, unintended steering inputs on fast descents, which also may be a good thing.

More upright position: Also good for lifting the front wheel (less weight naturally carried on the handlebars), looking around.

Fatter tires: can handle more varied terrain.

I'm a roadie. I don't ride CX, but as far as I can tell, a CX bike is "road-plus" in terms of its capabilities. Put slicks on it and it is a road bike. For grass and dirt, it's fine. For riding over exposed tree roots and big rocks, not so great. A mountain bike is really better suited to off-road riding if that's where you'll be spending the majority of your time with this bike.

Answer 3

Here in Belgium the Cyclocross is used a lot. The championship is a very popular winter sport, and is covered live on national television. It is specially suitable for the terrain here. Flat terrain with a lot of mud and sand.

The cyclocross bike cuts through the mud, and rides on the solid undergrond of the mud, where the MTB floats on the mud. The brake system (cantilever) is more capable for dealing with mud as disk brakes. And they are a lot lighter, specially compared to the 29-er.

The MTB has sturdy tires and suspension, and smaller gears. It is more suitable for rocks, climbing and downhill.

On the organized tours (flat and muddy) here you see a lot of MTB-26's, and a few 29-ers, since they are more comfortable to ride. There are about 2% cyclocross bikes. They are mostly a bit faster, but this could be due to the rider.

Even on the terrain that the cyclocrosser is made for, some "pilots" complain about their wrists after 2 hours of cycling, since they have no suspension and more weight on their arms. Tree roots an stones give more punctures.

Conclusion: On sand, grass and mud the cyclocross bike is a bit faster as a 29-er, but not as comfortable. On rock, steep hills or longer off-road rides the cyclocross bike is not that good.

Answer 4

I own a 29" MTB and a Cyclocross and while I use the CX for winter commuting, trips to the zoo and riding through the park, the 29er is basically for singletrails and mountains only. I rode most of the trails I ride on the 29er with my CX, too (pretty hard work though :) ), but I HATE riding the MTB on the road. So basically I would ask myself, do you want your bike strictly for "sport" in the mountains and woods? Go for the MTB then. Or do you want a versatile bike for everything including some mild wood & trails? That would be the CX.
I also think a 29er is a much better choice of MTB if you take longer trips or end up on roads once in a while.
I hope this helps!

Answer 5

Comparing a 29'er and CX is like comparing apples to oranges. The 29'er is a special variation of the Mt. Bike. The CX is a completely different beast.

Extending what Traimax said, I think you may have narrowed this down the the wrong choice ( a "false choice".) (And I have ridden a CX bike (my first bike out of college, 18 years ago) and currently have a Mt. Bike (similar to the above) and a road bike (similar frame to your CX above but with very thin tires). I could not easily (and thus never did) ride my CX bike off road. I could have ridden it on a flat, smooth dirt/cinder trail but not on a gravel trail (if the gravel was more than 1" or so deep).

The differene b/t a 26" and 29" is minimal (in my very limited experience riding one a few times) unless you're riding on very rough stuff and then it just means you get over stuff a little easier, but I suspect it won't be the difference b/t being able to do a particular trail or not. However, the difference between skinny and wide tires is enormous. It can easily be the difference between being able to do a trail or now if that trail is muddy or has a lot of gravel.

I'd recommend flat (mt bike) style handle bars and wide(r) tires. I don't think the suspension (of a mt. bike) matters much unless you're riding on rough trails. And you do save some weight and a lot of cost by leaving out the suspension. If the two options you presented are your only options, I'd say go for the Mt. Bike. (It'll cost more but give you more flexibility).

If you have other bike options then:

The bigger decisions are:

• Drop handlebars (style in your CX photo) vs flat (Mt Bike style).

  • I don't think there is much advantage (despire your experience with it) of drop bars unless you're doing a lot of road riding. Even on my road bike, I'm usually not in the drops, I've got my hands on the horizontal bar above it. In fact, most modern Road Bikes I've seen have a style of shifter that is integrated into the brake levers so that you can shift from the drops or the flats, so I think a lot of people spend a lot of time on road bikes on the flat portion of the bars (not in the drops).
  • There are a lot of advantages to the Mt. Bike style handlebar. It gives you much better manuverability, control and levarage. You can pop the front wheel over a rock (or more easily bunny hop over a stream or mud on a trail, or a curb on the road) and your hands are more solidly on the bars.

• Thin tires or Mt. Bike style wide tires. Thin tires are faster b/c you can inflate them to a higher pressure and thus get less rolling resistance. That is their only advantage and it really only applies on flat pavement. (Might apply on hard packed ground but your reduced traction offsets this, meaning you're going to have to brake in turns. So I'd say the speed advantage is a wash unless its smooth ground with good traction (i.e., paved). Thin (skinny) tires give you less traction and sink into gravel or soft ground. As TrailMax said above, you can always put slicks (smooth tires) that are thinner on the Mt. Bike (although not quite as thin a tire as you could on the CX boke) but you can't put much thicker tires on the CX bike.

Answer 6

I would say 29" in mountain bikes is a buzz word indeed. If this is your first mountain bike, do not make it 29". The selection of bikes, wheels, tires are quite limited comparing to 26".

Decision MTB vs. CX is entirely up to you. All depends on what do you mean by off-road. Off-road can be country roads or Alps singletrack, or downhill trails.

From my experience wheel size is not the major factor in being able to ride off-road. It is all depends on rider technique, bike can only help. If rider is afraid going down the slope, no bike will get him down.

If I had to choose between MTB or CX, I'd go for MTB with the following reasons:

• Cyclocross bike is not quite road bike and not yet mountain bike.
• You can put slick/thin tyres on MTB and it'll be rolling better. But you can't put fatter tyres on CX.
• If you want rougher terrain, MTB can go anywhere, with CX you'll struggle.
• I guess you already own a road bike, why not try something new?

Hope this helps.

p.s. my opinion is biased towards MTB, as I'm MTB rider for more than 12 years.

Answer 7

I have a cyclocross as my commuter, and a 26" MTB bike. I rode a loaned 29er for a mtb race this year, and while trying it out in the city, I noticed that I could hit the square curbs in the neighborhood and flow over them, much better than the 26" bike. No need to hop the front wheel.

If this will be your only bike, go with the CX. They are usually built with the CX racing in mind, which means running reasonable good when its crufty dirty. Means that you can get away with less maintenance if necessary, compared to a pure road bike. You can put skinny tires on it, and its a road bike. The extra brake handles on top give you more positions for riding comfort. I find that you can feel all the bumps in the pathways (like frost heaves and root bumps). This could be because I have skinny tires at 120psi, and the carbon fiber fork does not absorb much of the bumps. You can catch the front tire in wider cracks, and hitting a root at an angle can be dangerous.

If you have a road bike, and are looking for a second bike, go with the 29er. The wider softer tires, combined with front suspension, makes most bumps disappear. The upright riding position is quite comfortable. If the trails you want to ride have roots or rocks, the skinny tires on the CX require a skill level that you dont need to have on the 29er. The wider tires take more energy to move and keep moving, and the tread will have higher rolling resistance, so it takes more energy to go the same distance.

Final test before you buy. Borrow one from the LBS, and ride it on the trails you are interested in.

Answer 8

There are a lot of factors to consider, many of which are touched on above.

I have both a 29" MTB and a CX, and I it's usually pretty clear which one I should be using given terrain, distance etc.

For me, it would mostly come down to this factor—what sort of surfaces you're expecting to ride most of?

You noted:

I am not particularly interested in technical riding–although I would like to be able to ride through most things, even if I have to do so slowly.

What is rideable on a CX isn't just about how "technical" it is—the tires are much smaller in volume and surface area, so this changes what surfaces you can (comfortably) ride. For example, there are a number of what many people would consider "non-technical" trails around where I live (e.g. firetrails) that are too rocky to realistically consider the CX.

So, I interpret your comment as that are looking at some light gravel, dirt and grass surfaces, and not singletrack (where tree roots, rocks etc. are a significant factor).

Some things to consider:

• Tires: As has been noted by others, MTB tires will tend to be larger volume. There are also a lot more "tubless ready" options which can improve traction and performance in off road use for MTB (very few options are available for CX based on my experience). The larger tires, with lower pressures, will "smooth out" rough surfaces significantly, even if you went with a non-suspension front fork, making rides more comfortable on rougher terrain. You will also hold traction longer on an MTB when climbing on loose surfaces.
• Riding surface: If you're riding significant sections of rocky roads/off-road sections (i.e. not small gravel/stones, but rocks > 5cm in size and/or significant drop-offs etc.) the MTB would be the best option. Also, CX bikes are not as "forgiving" on the body if you have a lot of bumps and irregular surfaces over the duration of your ride. To my understanding, CX races/bikes are typically used for shorter stints in the saddle (e.g. races around 1hr in length) and you will fatigue (i.e. in the arms etc.) more quickly on a CX when not on relatively smooth surfaces. I've also noticed that my elbows get jarred on some surfaces on the CX, that I wouldn't even notice on the MTB (even when in the "attack" position, with elbows held loosely).
• Braking on downhill: I've found that braking on a rough/off-road down hill is harder/less comfortable on the CX than it is on the MTB. This is in part due to the location of the brakes on the bar but also the position you need to hold on the bike (which has been noted by someone earlier). As I'm used to a flat bar setup (even my old road bike was a flat bar) I'm still getting used to when and how to use drops—so this may be a rider experience thing. But the MTB is definitely easier to handle in this regard.
• Weight: the CX is likely to be lighter (sometimes significantly) than an MTB due to tires, suspension, dropper posts etc. If you do a lot of climbing, or have to carry the bike any distance, this may be a factor.
• $$: The distance between a CX and a hardtail in terms of cost is not a lot, but you are paying more for suspension and other ruggedised componentry on an MTB. The gap widens if you are considering a dual-suspension bike (which I assume you're not given your description).
• Gearing: My experience is that CX bikes tend to be geared more towards performance/speed, whereas MTB is more forgiving on climbs (unless you're looking at a 1x11 setup, which I don't suspect you are). I run 2x10 on both bikes, but the MTB has a lower "granny" gear than the CX. It doesn't sound like you have a lot of off-road climbing (otherwise you probably would have mentioned it in your description), so this probably isn't an issue for you.
• % of Road vs. Off-road: The MTB can ride anything the CX can, but if a majority of the ride is on tarmac (sealed surface road), the MTB is definitely not the right choice. While the CX is a bit more limited in the surfaces it can cope with, it is way better on the road in my experience. The amount of road riding you do will also influence tire choice—a lot of tarmac you'll want to consider a file tread pattern, a lot of off-road more "knobby" style patterns. In my experience there are more "road friendly" CX tire options than in the MTB world (I was looking to convert a hardtail to a hybrid at one point).

One thing I'd suggest is that riding style on a CX is more like MTB than road riding in terms of stance and general riding technique. So if you're coming from a road bike, this may take a bit of getting used to.

One last thing: I'd suggest an addendum to an earlier commenter's note about 29" wheels only being suitable for taller riders. Frame size is a much bigger factor than wheel size AFAICT, but I've noted some manufacturers will offer a 27.5" in their small frame. So I would regard this comment only if you are considering small frame sizes.

That said, if you are considering 26" MTB, I would recommend considering 27.5" instead. Manufacturers seem to be standardising on 27.5" or 29" configurations.

Answer 9

CX bikes are really intended as special purpose bikes (Cyclocross racing), however plenty of people do use them on the road. I would bet very few people use them where mountain bikes typically go. As someone else said, comparing a CX to a MTB is like comparing apples and oranges.

If you could shed some light on where you plan to do most of your riding then the choice might become more clear.

Answer 10

Many answers but none seem to focus on practical implications

First consider what a CX is designed for. It is design for maximum speed on what is basically light trails. CX is also designed to be shouldered. Most CX courses will have a run up that requires the bike to be shouldered.

A mountain bike is designed for wide range of trail conditions.

A 700 and 29" is the same diameter (ISO 622). The mtn bike will have larger diameter tires. Most CX will go up to 38mm but some pure race only 35mm.

You definitely give up stand over with a CX. Since the CX needs to be carried they make the triangle big - more room to shoulder and less distance to the shoulder. On a slight fall the extra clearance can sometimes be VERY valuable.

On a light trail speed advantage goes to CX. That is what CX is designed for. You don't need a shock and a shock absorbs pedal energy and adds weight. Smaller tires are more efficient. Larger triangle is more rigid / weight. Drop bars are more efficient. At speed you have better aerodynamics with drop bars.

Clearly on rough (rocks or roots) the mountain bike has an advantage. Bigger tires and a shock.

On a climb the geometry of the mtn is more efficient. Don't ask me why but I can tell you from experience it is.

Drop off. This is the big difference. On moderate to steep decent the mtn is way better. You can get you weight (butt) back and still be on the brakes.

On the road CX has a huge advantage.

There is a CX course near my house and I train on my rigid fork mountain more than my CX. The reason is the downhill is just so much more comfortable on the mtn and I am just training. My times vary by less than one minutes on a total of 50. So about 2%. The mtn is faster up and down the hills. And the CX is faster on the flats. You see a few mtn bikes in the lower classes of CX and for people that don't have decent technique a mtn is better (easier descents).

There are some trails by my house and there are only few sections I can ride on my mtn but not on my CX. There are some drop offs I ride on the CX but much more comfortable on the mtn.

For people that say apples and oranges I don't agree. My CX has about the same feel and balance as my mtn. My road has different feel and balance.

For light trails definitely CX. But a mountain is not wrong. With a mountain you have the option of more technical stuff if you decide to in the future.

Answer 11

• I am currently running a Trek Superfly 5, with some cheapy 700cX43mm hybrid tires at about 80 psi. It has a lock out front fork with
  100mm of travel and disk brakes for handling. It is running a 3 by 10 gear set that is a little slow for road biking but will climb over
  anything (especially with some low pressure knobbies). The bars are a little wide for road use but other than that is seems to make a great commuter vehicle. It rolls well over any terrain I will encounter.
• This is a versatile machine: lock the front for the road; unlock
  the fork for grass fields,sidewalks,and nasty roads. All I need to do to make this a super fun trail bike is a simple tire switch.
• The most important deciding factor is the tires. What I am essentially riding is a hybrid with high end components and this
  is because of a simple tire change. Anything from your CX to a
  hybrid to a XC 29er will likely do what you want. The question is how road or trail specialized you want to go in the geometries.
  The speed on road or trail is mostly just a matter of tire
  choices. (The XC29er has the most wheel choices though.)
• My vote goes to the 29er.

This is 2015 though so things in the MTB world has come a long way.