03 August 2010

bikefix Exclusive: One Reviewer’s Take on the 29er vs. 26er Debate

I recently got a kind of garbled question after reviewing a pair of Edge handlebars. This person asked a few questions, one of which was how I like 29ers over 26ers (if this sounds foreign- I’m talking about wheel diameters). This is, of course, one of the big questions (and debates) occurring in the mountain bike media and world right now. I thought I would take a stab at clearing the air, since I seem to be one of the few people who enjoys both wheel sizes.

One of the things I hear proponents of 29ers saying all the time is “there is no comparison, they are just better and faster” or something along those lines. This just isn’t true. Don’t get me wrong, many times it is true. In fact it may be true more often than not, but the blanket statement isn’t correct. 29ers tend to be faster on many trails, but that’s what it comes down to, the trail. If trails are tight, really technical, and have long uphills and long downhills, 29ers don’t shine quite as brightly. A large part of this is because hardtails don’t do as well on really technical climbing, and most 29ers out there these days are hardtails (for reasons we will discuss below). So half of the 29 vs. 26 arguments come down to what trails you like to ride or what type of trails are even available to you. If you live in Wisconsin or Kansas, you might feel that 29ers are vastly superior- and for you, you’d likely be right. The problem is that some of us live in places where we have trails that show the strengths and weaknesses of both. We, Albuquerque riders that is, have a foothills trail system that 29ers absolutely fly on, but we also have trails in the Otero area that will punish 29ers (hardtails in particular). We actually got a former racer and 29er fanatic to ride this area and he admitted that he could see where a 26 inch wheel would be beneficial. Trail type is important to keep in mind when discussing 29er vs. 26er.

One of the big untruths spreading around the internet and in print is that a 29er has a larger contact patch with the ground. Here in the US, pressure is measured in PSI, which stands for “pounds per square inch” and can be understood to be a measure of the amount of weight that can be supported by a square inch of tire. Basically, if you are riding with the same pressure in your 26inch tire as you are in your 29er, the contact patch will have the same area. A 29er will have a differently shaped contact patch of course, and this could be either good or bad, but no study has been done on this aspect. My impression is that the 29er will have a longer but slightly narrower and longer contact patch and the 26er a shorter but slightly wider patch. It then seems that the 29er might give more forward traction while the 26er might give better cornering traction, but I am just theorizing here. My editor-in-arms feels that the opposite is true because he can corner better on some 29er tires than on identical 26er tires. This is an interesting observation and maybe he is right, but there are too many variables and we haven’t even tried to figure out a way to test this. His observation could be something as simple as the fact that the circumference of the 29er tire is effectively turning slower than a 26er at a given speed, which means it won’t break away as quickly, or maybe it just feels faster, or perhaps the tires aren’t as identical as we thought. The point is that the contact area is the same, even if the shape is different. Interestingly, the trend on in the road world is towards shorter and wider contact patches. HED have done research that suggest that such a contact patch can significantly decreases rolling resistance and enable riders to run lower tire pressures.

We’ve also heard it said that 29in tires are less prone to pinch flats than similarly-sized 26in tires. Because the ability of a tire to stand off the sort of impacts that cause pinch flats is directly related to the cross section of the tire (generally its width, but here really the distance from the tread to the rim), the pressure being run, and the construction of the tire (especially the stiffness of the sidewall), we’re going to call BS on this claim. The 29er’s lower approach angle has very little impact on how a tire ‘looks’ to a square-edged rock or curb- that rock has to travel through the same amount of tire either way.

Frame builders have to make some compromises when they build 29ers. On hardtails they are mostly minor and some are getting sorted out. Nobody we can think of has quite figured out how to make great 29er full-suspension bikes though. Yes, they are getting better, and there are some examples out there that are very nice and fun to ride, but unless you are about 6’1 or taller, compromise is the name of the game with full-suspension 29ers. This is part of the reason there aren’t that many suspended 29ers on the market- packaging already complex and flex-prone suspension systems as well as larger wheels is a challenge. The gap is narrowing, but there are mechanical realities about long, unsupported spans that make working around a bicycle’s fixed points (cranks, saddle, handlebars) that much harder. In a weight-obsessed industry (obsessing over weight is we’ve argued against), there is also the unavoidable fact that a 29er will weigh more than a comparable 26in bike. Sure, there are 21lb full suspension 29ers available, but those are so far outside of most riders’ financial reality that they may as well be imaginary.

There are also a couple of other minor niggles with the 29er format. The first is that the lack of true UST tubeless tires and wheels. We are huge fans of tubeless tires here at bikefix, and there just aren’t that many options for 29er. Yes, there are a lot of riders doing the “ghetto” tubeless thing but that is very hit and miss, as even its biggest supporters will admit. The second thing is that, like frames, 29er wheels are inherently weaker wheels. This isn’t a very big issue because people seem to have accepted higher weights so we aren’t seeing many breakages, but it is a fact nonetheless and something to think about if you are a beefcake or tend to be hard on wheels. The exception that proves this rule is the three years’ use that Marc has gotten out of a 1600g 29er wheelset built using sensible hubs and road rims.

I’ll be honest and say that, despite having owned one, I haven’t yet spent a lot of time on full suspension 29ers, but I’m keenly aware of the limitations of the hardtail 29ers which I own- and the knowledge that the full suspension 29ers have even more limitations. One of the bigger issues with 29ers is the height of the handlebars from the ground, and relative to the saddle. The larger size of the wheel adds to the length of the fork, this in turn raises the cockpit. For those of us who are medium to short in stature though, the saddle height doesn’t change much, and this means it feels kind of low compared to the handlebar height. This discrepancy is hard to overcome as most frame builders have come to realize that there is a limited range of heights from the ground that a bottom bracket can be, and still ride well. That is why you see many of us 29er owners (myself included) trying to lower the bars in some way. Many riders use inverted stems (which I personally dislike) and others try all kinds of different handlebars, or really short forks (rigid ones even). In an attempt to combat this problem, designers started building shorter head-tubes on their frames so they wouldn’t ride as high. This however, allows more flex to creep into designs that already had flex issues due to the taller wheels and places even greater stresses on head tubes, headsets, and steerer tubes. The new generation of suspension forks with tapered steer tubes will help this a lot, but the issue remains for now.

Another issue that exists with 29ers and in particular FS 29ers is the length of their wheelbase. If you try and keep it shorter to feel more nimble, you run into a bevy of problems- tire clearance, chainring clearance, and downhill ride characteristics to name a few. The further back you push the wheel from there, the less nimble the bike becomes. The extra room needed on a suspension bicycle exaggerates this. This makes the bike more stable though and that is a good thing, and I embrace that. That is also one of the many reasons 29ers feel different than 26ers. In turn, I feel that is the single best attribute that a 29ers have- they feel different. It is a very different ride than a 26in bike, and I dig it for that. I think that’s why so many people that have been in the mountain bike industry for so long are into 29ers- they dig it man! This feature alone is well worth all the growing pains that 29ers have gone through (and will continue to go through).

In the end, you may live in part of the country that favors one wheel size or the other, or like me, you may dwell in a region that has trails for both. I’m just tired of hearing that 29ers are the “answer” or that they “destroy 26ers.” While we’re all for people being enthusiastic about their bikes, 29ers are not the magic bullet that some claim. They are both great and if you are an enthusiast who rides in a variety of terrain, you will probably end up with a bike of each.

charlie

This is just the beginning of the conversation. bikefix would like to invite anyone to weigh in on Charlie's points with their questions or opinions. Let 'em rip...

6 comments:

Anonymous said...

I generally agree with this point of view. However, I do believe that a longer contact patch (assuming a constant surface area) will provide more lateral friction (better cornering). For example, the skid of a sled is harder to move sideways than along its length.

David Benoff said...

Cool article, but I'd go back and omit the bit about Hed and rolling resistance.

Hed's claims about reduced rolling resistance have to do with the straighter sidewall profile you get with a wider rim, nothing to do with the contact patch.

Hed's claims about RR are likely bogus anyway. They won't release data to back them up. Good discussion here:

http://www.biketechreview.com/forum/1-general-discussion/26305-wide-rims-and-rolling-resistance-shootout

bikefix said...

David,

It's interesting that the people in the thread you linked use rollers for efficiency measurements. It's a good way to isolate out a number of variables, but as road texture and aerodynamics come into play, I'm sure things get a whole lot cloudier... HED should come up with that white paper, though- they're opening themselves up to criticism there.

marc

kippsters said...

I would just like to start off by saying my 29er makes me coffee every morning before I ride, and I now clean most techie sections one handed. But going from a 26 hardtail to a 29 FS, over two years ago, here are a few observations. In slow, technical areas especially going down, the 29 suffers. It is not as stiff and the lack of precision is noticeable. That being said, instances where there is a bit more room or a straight drop I like the wagon wheels and feel faster and/or more confident. On tech uphill, I think it is a wash, but I have never owned a really nice FS 26. I think you nailed it when you said it boils down to feel and what you like. I demoed or borrowed 5 or 6 FS bikes before I made a decision and I picked the RIP 9 because it felt fun, and other than the Maverick, was the only bike that felt really efficient and climbed well. I tend to like faster flowey downhill, not super technical slow stuff, and that matches up with what 29ers do best. I do wish the bike were stiffer, and the geometry were a bit different, and that the headtube didn’t oval, but the bike is fun and capable. What I really need is the budget for two FS bikes and then it would be a non-issue.

Adam Simpson said...

Good article, Charlie. I'm glad you gave the straight-up meat and potatoes strengths and weaknesses of 29ers. I've been riding 29ers for a few years now and I've ridden an enormous variety of terrain on both my hardtail ('05 Fisher Paragon) and my FS ('08 Niner Rip 9). The number one reason I like 29ers is that they simply fit me better. At 6'2" with long limbs, I have a high centre of gravity. On 26" wheels, I always feel up above the bike. On 29" wheels, I feel more "in" the bike. This outweighs all the other factors of rolling efficiency and traction and attack angle etc. Proportionally, 29ers work better for tall riders than small riders. With tall riders, issues of extra-long wheel bases and too-tall bar height disappear. A long wheel base works better with my high centre of gravity and keeps my front end on the ground on steep climbs. I have more than 1" of spacers under my stem which means that on a 26" bike, I'd have even more. With each North American generation being slightly taller than the previous, more and more riders will feel comfortable on big wheels.
It is absolutely true that 29ers feel more cumbersome in tight, technical sections and some corners, I simply cannot make. But keep in mind, I am a tall guy on a long, tall bike. It doesn't matter what bike I ride, I will always be at a disadvantage in the tight twisties compared to my smaller riding mates.
29ers are also more flexy than comparable 26ers. Long fork legs, shallower spoke angles, shorter head tubes, larger frames. These have all been issues but have become stimuli for R&D solutions that benefit the entire bike industry. We are now able to buy tapered steerer tube forks, stronger head tubes (see Intense, Niner and Lenz), tougher rims and in 2011, larger-diameter forks.
I was hoping you would have touched on the claim that 29" wheels make a hardtail feel like a 2"-travel 26er. Bogus!!! Trust me, if you wheelie-drop a 20" rock, there will be no mistake that you are on a hardtail. If you slam your rear wheel into a big rock or root, it will be painfully obvious you are still on a hardtail when your rear tire pinballs off it and tries to either compress your spine or throw you off the trail. Big wheels are not a substitute for suspension!
During an MTB trip in Pennsylvania a few years back, we went to an area called the Laurel Highlands. This is where rocks were invented. The trails were covered in jumbles of random, angular, pointy rocks. We asked the guys in a nearby bike shop in State College what the bike of choice was for the area. They said that a rigid, single-speed 29er was best. I think they drank a little too much of the 29er cool-ade.
Here's a little stat from TrekWorld: over 60% of hardtails that sell for over $800 US ($1000 CDN) are now 29ers. 29ers are selling for a reason. They've matured to the point where they are now more fun to ride than a comparable 26er.

bikefix said...

Adam,

Thanks for the well thought-out comment on 29ers. It is very true that at your height and above, 29ers take on a different roll- that of the bike that finally fits well. I did mentioned this in my article, but perhaps I didn't follow it up enough. Although they still have a few of the same issues (like wheel strength) they are much more of a normal fit for folks who are taller. Outside of people who are quite tall, the key issue remains the kind of terrain that you usually ride, because that tends to determine what type of bike or wheel size works best.

I do realize that technology is quickly making full-suspension 29ers much better, but it hasn't yet solved all the issues that they have (maybe soon though)- especially if you are vertically challenged. All that being said, I know a few very tall guys who feel comfortable on, and still rip on their 26ers too.

I'm not surprised to hear your statistics and I'll assume your statistics are true, but the problem with statistics is we all make different inferences from them. You see a product that has "matured" enough that they out-sell their 26er sibs. That may be true, but I see it as a product that puts a new grin on my face. Like I said before, it's different and fun (and often better), but it's the "different" that hooked me.

-charlie