Tubeless is great, until it isn't

15/02/26 16:54 Filed in: Riding

I've been running MTB tyres without tubes for close to 20 years. I can count on one finger the occasion(s) that tubeless failed me on the fat tyres.

Road is different. Pressures are higher. And in Canberra, the number of items lurking on main roads that cause punctures is also way higher than any off-road scenario. The lure is strong. I used to interrupt road rides with nauseating regularity to replace a punctured tube. The combination of my weight and the glass fairies doing their job well meant never a month went past without a flat. Sealant should fill in any small holes - usually without the rider even noticing. That's the theory. Ride along secure in the knowledge that only a massive failure will spoil the flow. The reality is that I've had numerous occasions where all the sealant has leaked out of a small hole without sealing it or the sealant has dried up and even a tiny hole leads to a failure.
I thought I was pretty safe using Pirelli Cinturato 28s - they rank high on the puncture resistance list and also low for rolling resistance. I haven't had a ride spoiled while on Cinturatos. But I recently found a thorn in one and when I pulled the thorn out, no amount of holding my thumb over the hole while keeping it at the bottom of the wheel (where sealant will pool) could get it to seal. Not that much leaked out, but when opened up, there was hardly any free sealant inside.
Since I hit the kangaroo, I've not been keen to ride along the river because of all the 'roos along that stretch. Instead, I've been enjoying riding home on the road. But as mentioned, Canberra roads are a field of glass. (So ironic that a thorn caused the problem.)
I solved my problem in the short term by replacing the tyre with the one spare I had on hand, filling the tyre with the prescribed amount of sealant, and pumping it up. My intention is to clean up the old tyre, patch the hole with a patch and reintroduce it to service in a few months.

Pressure is the enemy of sealant sealing. Twenty psi in the MTB tyre is fine. Seventy psi in the road tyre is the limit. Less would be better. I would like to upsize my tyres (again) to downsize my required pressures. Not only for the peace of mind I'd get, but also for the smoother ride.

Michael Hanslip Coaching

If you want to go faster, you have to pedal harder

Tubeless is great, until it isn't