Over the last few years, wide rims for bikes (road and mtb) have become more common. Back in the day, wide rims were the norm until a certain Mr Bontrager came along and re-rolled Mavic MA-2 rims from 700c to 26″ wheel size. Why? quality and weight: the aluminium rims were much lighter and easily as durable as the poor quality offerings available at the time specifically for mtbs. With wheels, there is always a balance point between tyre performance, weight and durability.
This re-rolled rim heralded a general move to sub 25mm external width rims. Tyres at the time were relatively narrow for the most part and with inner tubes, you were running 25psi+ in order to avoid (frequent) punctures.
Fast forward to Surly releasing the Pugsley with the ridiculous Endomorph tyre. Yes, DH bikes had arrived and wider rims and tyres were not unheard of, but they were too heavy for XC use for the most part. The Endomorph was designed for truly questionable terrain: snow and sand. Even with the 50-60mm trials or the Surly rims of the day, sub 10psi was a *maximum*.
My first experience of a Pugsley was riding hot laps on Shaggy‘s Pugsley at Bristol Bike Fest. The race course is baked dry, usually, in the summer and was very rooty with low amplitude rocks and rough trail in places. On the Pugsley, you could charge into the roots, overtake other racers in the rough next to the smooth line and bomb the descents with abandon.
There was definitely something to this.
In the proceeding years, I experimented with light tyres and lighter tubes as I moved to 29″ wheels. It was’t unusual for me to ride 600g tyres with 100g tubes. I flirted briefly with tubeless systems, but struggled to get my tyres of choice (Continental) to seal well. The sidewalls were very porous and the interface with the rim bead seat was loose.
In the end, I began to use a small amount of sealant inside very light tubes, but I’ll admit I was plagued with punctures.
Many years ago, I had procured a 50mm wide Uma ‘snow’ 29er rim. This was heavy, singlewall and of questionable strength, but it changed the tyre profile out of all recognition and if the interface had been better, I would have relished the low pressures I was able to run with minimal risk of pinching.
I stopped using this set up because the angle of the spokes combined with the relatively noodly rim made me suspicious it would fold in use. That, or the tyre would roll off the rim. Still, it was interesting.
Wider hubs, or at least flange spacing, make all the difference.
When Surly, again, led where others follow and produced the Krampus I knew I wanted to try the new, 29+ wheel size out. The raison d’etre for this frameset was fitting the, frankly, ridiculous Knard 29 ‘plus’ tyre. 700c but 3″ wide. Huge. Having messed around with Endomorphs and then Nate tyres on the front of my bikes for a few years and the brief spell with a wide rim and standard 29er tyre, the likelihood was that it would work well.
It was a game changer.
The full-on fat bike tyres of the time were heavy 1300-1800g. The Knard offered a lot of floatation, shock absorption and did so with a relatively small weight penalty over a normal 29er tyre: they weigh 1000g or so.
Yes, the sidewalls were thin and the tread pattern minimal, but in fairly short order there was reasonable choice on the market and with the Chronicle from Maxxis, EXO sidewall protection. 9psi and 35-50mm rims is a magic carpet ride for a rigid bike.
I started using carbon fiber rims a number of years ago as it is a fantastic material to make a light, strong, stiff rim from and this pays dividends particularly as the rims become wider. Indeed, it allows the whole ‘plus’ tyre thing to be fully realised. One of the main detriments of plus bikes is the added weight of the wheel at the outer edge. With the development of improved tyre-rim interfaces and tyre construction, tubeless is a snap. Light, wide rims paired with wide tyres make for a superb system for covering rough ground.
Lately, for 29ers, I have been looking seriously at Kappius’ offering, the 46mm external/40mm internal, cross country orientated KR-XCW-29, with a weight of 435g +/-15g and a good looking profile to facilitate tubeless set up. I have appended some links regarding the Kappius offering at the end of the post.
Things were turned round again with the arrival of the WTB Trailblazer, a 27.5+ tyre – in essence a 650b bead size, with a 2.8 to 3″ tyre, designed to retro-fit in 29er frames, but offer much of the benefit of the 29+ Knard. In the words of Bob Poor: “the idea was hatched in a seine skiff while catching 20,000 lbs of salmon every hour in the remote waters of SE AK”.
I am very glad Mark Slate at WTB took the idea on and had the tyre mould made. The 29+ is amazing, but in some instances the huge diameter is a slight hinderance. I’m going to come back to this; I have been having some interesting conversations with bike designers on the matter that do not feel concluded and I am also in the embryonic stages of working with Sean at Vertigo Cycles on a 27.5+ bike, perhaps like this one.
As much as you hear complaints that there are too many wheel sizes available at the moment, choice is a good thing to have.
“The wide world is all about you: you can fence yourselves in, but you cannot for ever fence it out.”
― J.R.R. Tolkien, The Fellowship of the Ring