Have a question for Lennard? Please email him at veloqna@comcast.net to be included in Technical FAQ.
Dear Lennard,
My disc brake road bike came with Mavic UST road tubeless wheels, which claim to be compatible with regular (tubed) clincher tires. However, I’ve really struggled to mount Continental GP5000s on those rims (my initial experience running the included tubeless 25mm tires did not make me a convert) — it invariably takes several tries, a good amount of cursing, and in one case thus far, a snapped tire lever. Given this experience, I’m concerned that fixing a flat by the side of the road would be a lot more difficult and time-consuming than it was in the good old days before tubeless. Any advice or special tricks to mounting clinchers on tubeless rims? Are there any rim/tire combinations that are known to be more thumb-friendly? The only non-tubeless-ready rims I’ve seen recently are those new Roval CL/CLX wheelsets, though they look like they share a rim bed shape with some tubeless wheels (center channel, etc.) — any reason to think those would be more clincher and “thumb-friendly?”
Worried about getting stranded by the side of the road.
— Walter
Dear Walter,
In a previous column, I discuss how to mount tight-fitting tires. And here are some in-depth answers directly from Mavic:
From Mavic’s road category manager:
When a tire is hard to mount, there can be two reasons: dimension and methodology.
Dimension
The wheels and/or the tire can be outside of their tolerances.
For wheels, the diameter is fairly easy to control, and rarely do we have a wheel going out of the required dimension. In case of doubt, the Mavic service center can get the wheels back and measure them.
For tires, it’s about the bead diameter and the bead stiffness. It’s easy to measure (although we were surprised to see that not all tire brands have the tools to do it!) but not easy to master at the factory.
Methodology
Most educated cyclists have known how to mount a tire for years and haven’t requestioned their methodology since tubeless wheels have appeared.
But the special inner rim bed of a tubeless rim requires a different methodology, whether you use your wheel tubeless or with a tube in. You’ll find it on this video for tire installation and one for tire removal.
Mounting
• Always finish the mounting of the tire at the valve.
• At mounting, when the last bit of bead is hard to pass over the rim edge, squeeze the sections of tire that are already on the rim to force the beads inside the inner channel of the rim. That will release the tension on the bead and help pass it over the rim edge (00:31 in the video).
Dismounting
• Start by unclipping the beads from the rim by pushing the beads inside the inner channel of the rim, on all the circumference of the wheel.
• Then, always start the dismounting of the tire from the valve.
Of course, it’s OK to use tire levers despite what was said at the very beginning of MTB tubeless in the late 90s.
— Maxime Brunand, Mavic road category manager
From Mavic’s global PR manager:
Brands are now supposed to comply with the ISO international norm (ISO4210-4775/ETRTO).
We know that there are still some tire batches in the shops that are not compliant.
We also had this discussion with some OEM partners, so we had to measure the tires they had and give proof that the problem was coming from their internal diameter.
It’s more difficult to respect the right diameter with rubber than us with aluminum.
You can also understand that if you mix a large diameter rim (due to production tolerances) with a small diameter tire (due to production tolerances too), it will be harder [to mount tires] for sure.
Sometimes, with no clear reason, we experienced that swapping from one tire bead to the other can help as both are not “always” exactly measuring the same diameter (rubber volume/vulcanization discrepancy).
Note down also that all the new models from the 2021 range have a modified internal rim shape to ease the mount.
We removed the lateral humps and widen the central groove to help even more.
Here is some additional info for mounting a tubeless tire following the right tips.
Squeezing the tire all around the rim, pushing it into the central groove, and ALWAYS finishing at the valve are key elements to succeed.
— Michel Léthenet, Mavic Global PR Manager
Dear Lennard,
I read your recent column in which a reader asked about tire compatibility with Mavic UST wheels. It was great that you were able to coax a response out folks at Mavic. I just wanted to add some first-hand experience confirming tire compatibility. I have nearly identical wheels (2018-19 Mavic Cosmic Pro Carbon SL UST) and have been running them tubeless with a variety of IRC (Serac, Boken, Marbella, Formula) and Schwalbe (P-One and G-One Speed TLE) tires without incident.
— Ben
Dear Lennard,
I’ve always believed this to be the best way to ensure a safe installation of a tubeless tire: Mount until they ping into place and deflate. If the tire stays on the rim bead, it is a solid install. I race gravel and endurance MTB, and over the past six years, I’ve mounted dozens of tires on multiple ENVE (hooked and hookless), Reserve, and Roval rims. Gravel, MTB, and road wheels and tires. Schwalbe, Maxxis, Veloflex, Continental, Vittoria, Panaracer. No problems ever on these rims. I use a Prestaflator and compressor. I don’t even need to use soapy water.
I’m facing a problem with three different HED Belgium wheelsets – 2 Plus and the new G. I’ve tried Schwalbe, Vittoria, Continental (tubeless versions), and other tires, and none of them will stay mounted when deflated. The tires are definitely seated when inflated (nice pings, even indicator lines). I’ve tried one, two, and three wraps of tape. HED, DT Swiss, Stans and Muck Off tape. I’ve tried multiple different widths of tape. I’ve tried soapy water and no soap. I’ve tried putting a tube in to get them to seat, pop one side off, and reinflate to mount the other side. I’ve inflated to the max pressure indicated on the tires. I’ve tried new and used tires. I’ve left them inflated overnight before doing the deflate check. Absolutely no luck on all three wheels. The only tires that I’ve been able to get to stay seated are Gravel King SK and one Vittoria Corsa Control TR (but only one of the four Plus wheels).
HED has been very supportive but has no idea what or why this is happening.
So, am I doing something wrong? And if not, is it safe to run a tubeless tire that will not stay seated when fully deflated?
— Joel
Dear Joel,
I’ve ridden plenty of tubeless road tires that wouldn’t stay seated when deflated, yet I was able to ride them without incident. I think there are plenty of rims that would give you this same problem, yet people are also riding them without problems.
You could use a tubeless insert, which would keep the beads in place. That’s certainly the safest way, other than gluing the tire beads to the rim walls.
Back in early road-tubeless days, the Hutchinson tubeless road tires were UST (meaning they held air without sealant), and the Shimano and Mavic rims were airtight without a rim strip and had a ridge on the inboard edge of each bead shelf. On countless airplane flights with my Dura-Ace wheels in an S&S bike case for a coupled travel bike, the tubeless Hutchinson UST tires did not come off the rims. The wheels won’t fit in that case unless the tires are fully deflated. The beads never popped off, which is good, because at the time I never traveled with anything more than a little hand pump, and I would not have been able to re-seat them.
With today’s tubeless-ready road tires, there would be no way I could do this. I find them generally to unseat upon deflation alone, and shoving them flat down into a bike case as small as the rim diameter would certainly unseat any that might stay on when initially deflated.
― Lennard
Lennard Zinn, our longtime technical writer, joined VeloNews in 1987. He is also a custom frame builder (www.zinncycles.com) and purveyor of non-custom huge bikes (bikeclydesdale.com), a former U.S. national team rider, co-author of “The Haywire Heart,” and author of many bicycle books including “Zinn and the Art of Road Bike Maintenance,” “DVD, as well as “Zinn and the Art of Triathlon Bikes” and “Zinn’s Cycling Primer: Maintenance Tips and Skill Building for Cyclists.” He holds a bachelor’s in physics from Colorado College.
Follow @lennardzinn on Twitter.