Fast-Rolling Rubber

17/01/23 12:20 Filed in: Gear

As long as I have been riding a mountain bike, I have been attracted to a fast-rolling rear tyre. I am quite sensitive to the perception of rolling resistance in a bicycle, and lowering it always seems better for me.
Low rolling resistance rear tyres (LRR for the rest of this entry) can be semi-slicks. These tyres have almost zero tread in the middle (the slick part), where the majority of pedalling takes place (ie, with the bike upright). But they have some cornering knobs on the sides that only come into play when the bike is tipped over for a bend. They can be quite large (check out the Minion SS from Maxxis), but even if they are small (I’m looking at you, Thunder Burt from Schwalbe) the lack of inner knobs can make them dig in quite well.
[Incidentally, when they first came out I bought a Thunder Burt once to try. I got about 4 km into my first ride when one of those tiny cornering knobs ripped off the tyre leaving a hole behind which my sealant wouldn’t seal. Schwalbe said “no warranty” and I couldn’t reliably patch it. That’s about $20 per kilometre!]
The ones I have the most recent experience with are the Pirelli Scorpion “R” tyres (in both XC and Enduro guise). They are not really semi-slicks because the knobs in the middle, while optimised to lower rolling resistance, do provide some bite for both pedalling and braking traction. Maybe a meta-slick? I installed a Dissector on my DH bike this summer because I couldn’t find one of the aggressive tyres I have used in the past. The Dissector isn't really either of these because the middle tread knobs are quite large, but few in number. It is not a clearly defined category; it's a gradient.
When the going is fast, such as descending a steep hill, I usually want for more rear tyre. I think Sam Hill might be fine with the slightly loose feel of even a brand new LRR tyre – but I am not. There is this one particular left turn at Thredbo that can be taken quite fast. On my Slash, with the Scorpion Enduro R rear tyre, I have to dab the brake to get around without sliding. On my DH bike, with the Dissector, I do not have to. Both the tyres and the bikes are enough different to not attribute it all to the tyres, but I believe with two "front" tyres on either bike (Scorpion Enduro M on the Slash and Assegai on the DH bike) I could go even faster.
When you are playing off the chairlift and especially if you aren’t racing, does anyone really care about rolling resistance? I think I will not in future.
On my trail bike I recently replaced the Scorpion XC R tyre with a Scorpion XC H tyre. Lots of small knobs designed to grip on harder surfaces. I haven’t ridden it yet, but I expect it will hang on better than the R tyre it replaced in all situations. Probably I should have simply matched the front “M” version of the tyre and been done with it!
Great Kiwi rally driver Possum Bourne used to tell amateur rally drivers to spend their money on tyres rather than some go-fast part for their motor. No extra power is getting to the ground if your tyres are rubbish. I think this will be my approach for MTB tyres in the future – not the spending thing because a LRR tyre costs the same as a grippier one – meatier rear tyres just make the bike feel that bit more secure. When you want to get down the hill safely and quickly, the meatiest tyre is always the right choice if you aren’t earning your living on the bike.

Michael Hanslip Coaching

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

Fast-Rolling Rubber