We recently tested the BMC Granfondo GF01 ‘endurance’ bike and were suitably impressed by its performance.
The broad and absorbent 28c Continental Grand Prix 4 Season tyres played a significant role in the Granfondo’s comfort, its calling card, but we couldn’t help but wonder how it would perform with slimmer, softer, grippier rubber. Racier, in a word.
Enter the Schwalbe Ultremo ZX tubeless. Eagle eyed, as ever, we noted the tubeless compatibility of the Granfondo GF01’s Easton EA90 RT aluminium rims, and acting upon the adage of birds and stones, united the newly arrived rubber with the recently tested bike. Simples.
A note of caution: if your rims are not tubeless compatible – the EA90 RTs are 17.5mm wide internally and equipped with a pronounced bead hook – do not attempt to run tubeless tyres. A failure at the speeds and pressures associated with road cycling would result in a nasty dismount at best.
Our fat-tyred friends have embraced tubeless almost unanimously, a technology with a multitude of claimed advantages including greater puncture resistance, no sudden loss of pressure in the event of a puncture, and greater traction and grip from running lower pressures without an unacceptable increase in rolling resistance. Too good to be true? We’ll find out in the weeks ahead. For now, here are the vital statistics.
Dispensing with the need for inner tubes should yield weight savings, so we began by weighing the Granfondo’s supplied set-up: a combined 760 grams for Continental Grand Prix 4 Season tyres and the supplied tubes.
Their replacement, the Ultremo ZX tubeless, equipped with Stans No Tubes valves (more of which below) and 40ml of sealant in each, tipped our scale at 710 grams, yielding a scant saving of 50 grams from the total bike weight. We’ll be looking elsewhere for performance gains.
Having removed the rubber supplied we the GF01, we set about mounting the Schwalbe Ultremo ZX tubeless. You can read our step-by-step guide here. It’s also impossible to overstate the importance of reading the manufacturer’s supplied instructions, even if doing so is something you usually resist with every fibre of your being (like I do).
Schwalbe insist that to avoid damage to the carbon bead, tyre levers should not be used. In the absence of a pair of Easton tubeless valves (the wheels were supplied with a test bike equipped with a clincher set-up, remember), we used the aforementioned Stan’s No Tubes, which appear to have worked well enough, despite the absence of a compatibility list from the packet.
The fit proved sufficiently snug, but not so tight that we couldn’t fit the tyres without levers or the supplied bead lubricant. We needed neither. Having mounted one side of the tyre to the rim, we poured in the Schwalbe tyre sealant. This can be a messy process, and care is required not to distribute it everywhere but the inside of the tyre when mounting the opposing bead.
Having done so, we inflated the tyre to the maximum pressure of 120psi to make sure that the bead was correctly seated (you can normally watch and hear it popping into place). Schwalbe claim a minimum pressure of 70psi, which should offer a suitable range for experiments on a speed-comfort axis.
Checking tyre pressure is part of our pre-ride ritual, and having done so, we were impressed by the degree to which the Ultremo ZX tubeless have retained their pressure, losing no more than a conventional clincher set-up.
Out on the road, the Ultremo ZX tubeless have thus far delivered a supple and lightweight feel; in the case of the latter, greater than the narrow weight saving over their predecessors would have had us believe. The rolling resistance is significantly reduced, and the wheels have felt quick to spin up in a sprint. The grip has so far proved excellent, and we’ll be experimenting with tyre pressures to see what can be achieved in terms of both adhesion and comfort.
In summary, this has been an encouraging start to our experience with a technology that has been slower to gain acceptance in the world of road cycling than it has off road.
We’ll report our progress in the coming weeks. Check back soon for a full review.