“The wide World is all about you…”

11 07 2015

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.

Syntace offered a simple exlpanation for the benefit of wide rims, which I would recommend reading, here. There is more discussion of value on the Open Cycles blog.

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


Kappius on facebook.

Kappius in Mountain Flyer.

Kappius on Fat-Bike.

Kappius on empty beer.

Kappius on Pinkbike.

Kappius on Vital mtb.

Kappius on Singletrack World.

Kappius on Cycling Dirt.

Kappius review on MarathonMTB.

Kappius on bikerumor.


Facts & figures.

9 07 2015

Spent 10 minutes measuring various wheel/tyre combos. Maxxis Chronicle 29×3″ on Nextie junglefox 50mm is 766mm at my riding pressure (9psi). A WTB Trailblazer on a Nextie 650bx50mm rim is 727mm and a Maxxis DHF 2.5 on a 30mm Enve rim is 742mm. The Nate on a HED BigDeal rim is 737mm at 18psi, which is higher than riding pressure. So it may drop a mm or two?

Why the measurements?

Fox announced a 27.5plus 34 fork recently and Rock Shox announced the Lyrik and Yari in a 27.5plus/29er casting as well.

The Fox is *likely* to have an a-c of ~532.8mm in a 120mm travel setting. This is an extrapolated figure as I could not find an actual a-c. for this fork. The 34 29er version from 2013 had an a-c of 542.8 for the 130mm travel model. Take 10mm for the reduced travel and you get the 532.8mm.

Now, add sag of 25mm, leaving an actual a-c of 507.8mm – but lets call it 508mm.

If I used a WTB Bridger or 27.5×3 Chronicle when they become available, the diameter is likley to be around 737mm or so – bit less than a good sized 29er – with me? so the radius is 368.5. Along with a 508mm a-c height this takes the total to 876.5mm.

The 29plus tyre diamter is 767mm so radius is 383.5mm. 876.5 minus 383.5 = 493mm. The a-c of some readily available carbon rigid forks, more or less.

A frame designed around this ride height could use a suspension fork with a 275×3″ front wheel or by swapping to a 29+ wheel, a rigid fork, with no real change in geometry.

Interesting, eh?

Oh, btw, the vinyl tape dropped 10psi in 24 hours without sealant, with sealant, no drop in 24 hours. Pretty stoked.

Edit: Fox tech specs are here. As you can see, the 120mm fork is 525.5mm a-c. This would put the equivalent rigid fork length at 485.5mm. Not bad at all. Oh, and the Fox 27.5+ fork fits 29+ it seems.

Tubeless tape.

6 07 2015

Forgive me for diving straight back into minutiae.

How often have you been frustrated trying to set up mtb tyres tubeless? Admittedly, recent improvements in tyre and rim interfaces have made a tremendous difference: nowadays, it is not an act of black magic to ditch your tube and have a reliable, burp free system.

One thing I have messed around with over the years has been tape. This is as important as good tyre beads, imporous sidewalls and a good bead shelf design. The usual tubeless manufacturers and indeed many rim manufacturers make rim tape of varying quality and utility.

I don’t like the Stan’s style tapes, generally. Stan’s is plasticy feeling with little stretch and I often find the adhesiveness lacking. For the most part, I have used Gorilla tape. I should qualify that, because they now make a clear ‘repair’ tape as well. I use the woven, black, duct-tape-type stuff.

Mostly, this is due to having early success with the provided Gorilla tape for Enve rims. I use Continental Revo sealant exclusively primarily due to a suspicion that ammonia based sealants are likely to be problematic, eventually, for aluminium nipples. It seems many mechanics complain of Gorilla tape failing in short order, I think likely due to the sealant type. Recently, I have found wheels ‘drying out’ as the sealant presumably cures over time, as the solvent is lost due to the porous, gorilla tape. Certainly the adhesive layers of the Gorilla tape seem to end up sponge-like and are a world of pain to remove cleanly.

The deep internal channels on some of the carbon rims I have used, or the singlewall HED rims with exposed nipple heads, have proven a challenge for non-elastic tape.

After doing a bit of reading about tapes, it turns out that Stan’s and similar tapes are simply packing tapes, available from the likes of 3M. There are various different types of tape and generally 3 types of adhesive: acrylic based, synthetic rubber and rubber.

The surface layer can be one of several, common materials (polyester, polyropylene, vinyl etc) with various conformation properties and elongation. Then there are unusual tapes such as Tyvek tape. It seems acrylic is typically a stronger adhesive.

If you poke around, you can find alternatives to branded tape, such as Tesa 4288 and 4289, which are incredibly similar to Stan’s. These are polyproylene with a rubber adhesive, the difference is how thick they are.

3m 8898 is used in some cases. It is also polypropylene with a synthetic rubber resin adhesive. Some report that it lacks adhesiveness. Clear gorilla tape is extremely sticky, as is Tyvek tape and both have been used to good effect. My concern is getting it off again if needed.

3m 471 is mentioned on some forums: it is vinyl, conformable, elastic but thin. It uses a rubber adhesive.

This made me look at other vinyl tape. I felt 471 would be a good choice but it is very expensive (£28 a roll, though admittedly this is 33m long).

In the end, I decided to purchase some 3M 764(1) which is the more basic vinyl tape with a rubber adhesive. Because I am not using an ammonia based sealant I’m guessing it will stay stuck. I have used it for the HED rims, where it is currently set up with tubes and 2 layers seems to be resisting nipple ‘poke through’. When it comes time to go tubeless, I will peel back one of the layers. It is very easy to work with and the greater elasticity is a boon. Oddly, when I deflated the tubes to inspect the tape, the tyres sucked in as if in a vacuum. I have never experienced this previously and I take it as a good sign that the tape is airtight. I have also just set up a Nextie 50mm wide 650b rim with a WTB Trailblazer, once I picked and cleaned all the Gorilla residue off. It is holding air without sealant currently.

Of course, this would not be quite as complete a preliminary report without some discussion of weight. I know, I know, it’s not much relatively, mud weighs more etc etc, but if I can save 50g at the edge of the wheel, for the price of some tape, that is nothing but a good thing.

The Nextie wheel weighed 1333g complete, as was, with Gorilla tape. Tapeless, it weighed 1278g and with the single layer of 764, it weighs 1295g. Not a huge saving, but the other benefits are likely to make it worthwhile

While we are on about tapes, 3m 8671 seems to be the ‘copter tape of choice. It is available in bike friendly widths and lengths. It is acrylic adhesive, polyurethane tape, 0.36mm thick, puncture and abrasion resistant. Good stuff.

Resources:tesa 4289Tesa.
Viking Tapes.
3M 764 vinyl tape characteristics.
Properties of 3M 741.
Properties of 3M 764.
Exploring adhesives.
MTBR tubeless tape thread.

Capital Trail 2015.

6 07 2015

Screen Shot 2015-07-06 at 13.55.23

Read about it here.