It doesn’t seem that long ago that 26” was the standard size for mountain bike wheels, the default setting… and we were happy. Then along came 29” and then 27.5” (650b) wheels and the mountain bike world was sent into a spin.

Back in 2009 26" wheels were the standard size for mountain bikes, but things were about to change.

Why 26” wheels? It was a case of ‘what was available at the time’ when when the founding fathers first starting building mountain bikes in the late 1970s. The only decent tire that could be commonly found in bike shops was the 26” x 2.125” Uniroyal Knobby, so that was it, mountain bikes were built using 26” wheels.

The 29” INTENSE 2951 downhill bike was ahead of its time in 2009.

There have been deviations along the way, 24” wheels made an appearance, and then early combinations of 29” and 26” wheels together, but it wasn’t until around 2010 that full 29er bikes started appearing in any large numbers. There had been experimentation of course, with smaller brands trying different wheel sizes out, but none were widely adopted until this point (and don’t forget that we at INTENSE had a prototype 29” downhill bike in 2009, the 2951). Then a few years later brands decided that the inbetweener size of 27.5” was the perfect combination of the two. The 27.5” or 650b size had been around since the 1950s, being widely used on utility and tandem bikes in France, and the idea was that it took the good things from both 26” and 29” wheels and put them into one, a good compromise.

Before we go any further it’s interesting to look at the way in which wheels are measured, because it is slightly obscure. Take 26” wheels as an example. The wheel itself is not actually 26”, that measurement refers to an approximation of the wheel with a 2” deep tire on it. A 26” wheel is actually somewhere in the region of 22” rim to rim. Add 2” of tire on either side and you have a 26” wheel… kind of. In the real world that measurement is 677mm, which is closer to 26.5”. It’s the same with 27.5”, the wheel is 23” rim to rim, then with a slightly deeper tire you have 27.5” diameter (702mm). So a 27.5” wheel is actually only marginally bigger than a 26” wheel – the difference in the diameter is just 25mm (1”), that’s just 12.5mm all the way around.

From 26”, to 27.5”, 29” and now ‘mullet’, World Cup downhill racing has seen it all.

The difference between a 27.5” and a 29” wheel? Around 38mm (1.5”), so a bigger jump, but add a Plus sized tire to a 27.5” rim (like the 2.8” Maxxis Minion found on the rear of our Tazer) and you actually have roughly the same diameter as a 29” wheel at 740mm. So in reality a 27.5” wheel isn’t half way between a 26” and a 29” as its name would suggest, it is marginally closer to the smaller 26” wheel size.

SO WHICH IS BEST, 27.5” OR 29”?
What a question. First we have to look at the differences between the two. Let’s talk about 29” wheels first. OK, so they are big, really big, and that means that they roll over stuff really well, whether that is a rock or a hole, they smooth out the terrain, they also carry speed really well, and generally fly around the place and make life easier. There is an efficiency both up and down. And because the tire is bigger it has a larger contact patch (the part of the tire that is in direct contact with the ground) than smaller wheels/tires, and that helps with stability and of course grip.

INTENSE Factory Racing team rider Aaron Gwin back in 2019 on board the 29” M29 in Andorra.

On the downside they don’t accelerate as quickly, turn as sharply or feel quite as lively as smaller wheels, and they can a have a slight neutral feeling to them. Because everything is bigger there is also some added weight compared to a smaller wheel set up. And then there is the issue of of ‘bum buzzin’ for smaller riders when things get steep. If you are shorter than around 6’ and like to hang off the back of your bike on steep descents, or tuck over jumps and obstacles you may find that the rear tire ‘buzzes’ on your backside. It is just the way it is.

Are 27.5” wheels more playful? I think IFR rider Seth Sherlock (on a Primer 275) would say so.

Bikes with 27.5” wheels are more nimble and playful, they accelerate and decelerate faster, love tight and twisty corners, are easier to manoeuvrer, in theory the smaller wheels also make it easier to ‘pump’ terrain to help you generate speed, the whole set up is lighter and a smaller wheel is always going to be stronger. It is difficult for designers and engineers sometimes to fit everything in on a bike, and a 29” rear wheel needs more space and that usually equates to longer chainstays which then means a longer wheelbase (making a bigger bike). This is not always desirable, with a 27.5” wheel you can have shorter chainstays, which gives you a more lively and playful feeling bike.

Trail excellence, Claire Buchar hauling on the Primer 29.

As with most things in life the idea of which is best mainly comes down to personal choice. Sure a 29er might be faster but the 27.5” is more fun… but what is fun to one person might not be so much fun for someone else! You really just have to weigh up what kind of rider you really are, and what kind of terrain you will mostly be riding on. You can still jump and ride tight and twisty singletrack on a 29er, just as you can go on all-day epics on a 27.5”.

Wheels on the ground or off the ground, Sherlock again on the Primer 275.

I guess you could say that if you do love to jump, ride parks a lot or ride very tight tracks then a 27.5” would be better for you. And conversely, if you like to cover a lot of ground, have a more ‘wheels on the ground’ riding style then a 29er may be better suited. If you are smaller you may prefer a 27.5” wheeled bike, but like we said, it is personal and it depends on a lot of factors. As with all of these things, if you can try before you buy then that will give you a better understanding of what the two wheel size options offer and which you may prefer.

Taller riders, like 6’ 2” Bernat Guardia, will probably feel more at home on 29” wheels, but there are no set rules.

We should mention that if you are new to 29” wheeled bikes that you will need some time to adjust to a slightly different style of riding. The timing changes, when and how you turn into a corner or how much you need to lean over, just subtle things that develop with time on the bike.

Aaron Gwin’s 2019 ‘mullet’ bike from the Mont-Sainte-Anne (Canada) World Championships.

Just to confuse matters a little bit more, there are of course ‘mullet’ bikes… business at the front, party out the back. Mullet bikes have mixed wheel sizes, at INTENSE we like to call these bikes 279(ers). A bike with a 29” wheel in the front and a 27.5” wheel at the bike, giving you the best of both worlds. In the constant search for the ultimate ride, 279 bikes could be just that. The ‘bump eating’ness’ of a 29er on the front, with the playful, nimbleness of a 27.5” on the rear. Some of you may laugh at the thought of running two different sized wheels in your bike, but mullet bikes have won downhill World Cups, World Championships and Enduro World Series races. So like Coke or Pepsi, Mac or PC, Nike or Adidas, before 279 bikes you were either a 29” or 27.5” type of rider, but now you no longer have to make that decision between the two… just go mullet!

At the end of the day it all comes down to personal choice. Ride what feels good to you and suits the type of riding that you do.

Here at INTENSE we have taken the approach that each individual bike needs to be designed around a specific wheel size or wheel size combination. Our Tazer eBike is a 279, and there is no hiding the fact that our INTENSE Factory Racing team has been testing prototype 279 downhill bikes for over a year now (the eagle eyed amongst you may have also seen another prototype mixed wheel bike on social media recently). Our M29 downhill bike is still very much our flagship bike, and don’t forget that 29” wheeled bikes are winning World Cup downhill races, they haven’t suddenly become obsolete, they are as important now as they have ever been. Our Primer Trail bike comes in both 27.5” and 29” specific models, and our longer travel Enduro bikes come in both wheel sizes, the Carbine is 29” and the Tracer 27.5”. At the short travel end of the range we are 29” only for both our Sniper and Sniper T models.

Still can’t make your mind up? Simple, just buy one of each!

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