“Most riders should go one tyre size up from what they are currently riding,” says Benni Skúlason, founder and CEO of Icelandic bike brand Lauf.
That’s across the whole range of riding, road and mountain bike, as well as the gravel bikes with which Lauf has made its reputation.
“I’m consistently amazed how long it’s taken people to accept that wider tyres are faster. But people are waking up to it now.
"You see riders at the Tour de France on 32mm tyres. A year or two ago, this would have been considered ridiculous."
Lauf has been ahead of the curve with its tyre clearance across its range, including Its first venture into road bikes, the Úthald.
“The Úthald can fit 35s, but it’s a race geometry bike. Testing shows 32s are the sweet spot for speed, without factoring in that you can ride longer if you’re more comfortable and descend faster if you’re more confident. Even without those two factors, 32s just roll faster,” Skúlason says.
“We have so much data now that is showing that wider tyres are just faster. But it’s a huge struggle for riders to get beyond the speed sensation paradox – narrower tyres give us a feel of speed and it’s really hard for us to accept that this feel isn’t true.
“Whenever you feel noise and vibration and a harsh ride, you feel like you’re going fast.
“It’s taken a long while to break this down. It applies to all genres of cycling: road, gravel and MTB. People just feel faster on narrower tyres, although they aren’t.”
Skúlason questions whether that general feeling is as a result of 32mm tyres being used on wheels optimised for 28mm and narrower tyres.
“Once wheels have been adjusted to work with 32s, maybe we’ll see 35s becoming faster than 32s,” he says.
Skúlason explains that construction is important too: "We’re used to narrower tyres being designed for speed, while wider tyres have been commuter tyres not designed for speed... so we draw the conclusion that wider tyres are slow.
“Use a wider tyre aimed for speed and the picture changes.”
Skúlason sees the move to wider tyres as something that will occur progressively across the whole spectrum of riding.
“The speed paradox is breaking down first in road, then gravel and eventually MTB. I think that’s because it’s so much easier to collect data for road riding.
“There are a million different kinds of gravel, but for road you can more easily standardise the surface. Getting consistent data for gravel is really hard,“ he says.
Is aero really all that matters?
Skúlason sees that ability to quantify the data and produce repeatable measurements as a major reason why bike designers are obsessed with aerodynamics, at the expense of other factors that influence ride efficiency.
“Wind tunnels provide repeatable data, which has led people to focus on the aerodynamic behaviour of bikes and tyres. People are optimising the tiniest details of their aerodynamics, but they’re ignoring the elephant in the room, like what tyre widths are fastest.
“Narrower tyres perform better in the wind tunnel, but not enough effort has been put into considering the other factors which are at play when riding a bike, because it’s not so repeatable.”
Skúlason argues that this myopic focus on aero performance comes at the expense of other important factors which determine a bike's ride quality. While they may be harder to measure, he believes improving rolling resistance and vibration damping benefits confidence when descending or riding in a group.
Skúlason says Lauf's bikes are designed to make the most of the advantages offered by wider tyres: “In Iceland, we have a relatively long history of riding gravel roads and people were settling in on 50mm tyres or so, because they found out they roll faster.
“I think gravel tyres should rarely go below that and in future we’ll see gravel bikes standardise on 50mm.”
As with road bikes, that’s significantly wider than the norm today, with the majority of gravel races riding 45mm tyres.
“I’ve heard people ask, ‘How wide a tyre do I need for this course?’ In that is the assumption that narrower is going to be faster and you should go wider only if it’s too rough.
“This is a fundamental misunderstanding – the optimum tyre width for The Rift gravel race here in Iceland is somewhere around 55mm. The speed you gain from being able to roll over washboard surfaces on wider tyres is huge.”
It’s not just road and gravel tyre width that Skúlason has in his sights.
“Most MTB riders are still riding 2.3-inch or 2.4-inch tyres, but there’s scope to go wider here too.
“It’s like pushing a shopping cart on a rough parking lot. You know how hard it is, but wider tyres at lower pressure will glide over the surface.”
1x13-speed offers drivetrain simplicity without the downsides
Along with wider tyres, Skúlason sees SRAM's new 13-speed groupsets as a key new technology that opens up gravel bike design.
Skúlason argues not many gravel riders love their front derailleur. They add complexity and weight, reduce tyre clearance and are less aero.
Plus, however good they are, he says they're prone to mis-shifts and chain drops – and changing chainrings interrupts your pedalling rhythm.
“The launch of SRAM XPLR AXS 1x13-speed gives people a new opportunity to re-evaluate their gearing choice and finally abandon 2x,” Skúlason says. “For most riders, it combines tight gear spacing with a range that is also wide enough.”
SRAM Red XPLR AXS gives single-tooth jumps between the 10, 11, 12 and 13-tooth sprockets, then two-tooth increments for 15, 17, 19 and 21-tooth sprockets.
That covers the range where most riders spend most of their time, while still offering a range that goes up to 46 teeth for the toughest climbs.
“You have equivalent gear steps across most of the gear range on the 10-46t to a 10-36t road cassette and I don’t hear people complaining about huge jumps with a 10-36t 2x setup,” says Skúlason.
“There’s the high-speed gears with tight spacing for top-level gravel racing, like Unbound, with a 46-tooth sprocket there for the climbs. We’re super-excited to add it to the Seigla.”
Skúlason explains Lauf is all-in on 1x for its flagship gravel bike. “The Seigla was designed for 1x only. Even with 12-speed XPLR 1x, the trade-off was completely worth it for the simplicity, reduced weight, low maintenance and peace of mind of 1x.
“The Seigla also takes advantage of the space freed up by going 1x to supercharge the tyre clearance.”
Skúlason says the 10-46 tooth cassette means there’s no compromise on gear range either: “When we launched the True Grit gravel bike seven years ago, one spec had a 2x11-speed SRAM Red groupset with a range equivalent to a 10-44t. But the new 13-speed has a wider range in a 1x setup.
“We’re super-excited about the new drivetrain. It hits a sweet spot for gravel, offering range plus tight gear spacing.”
SRAM’s Full Mount design also means you ditch the derailleur hanger – often a bike's Achilles heel.
It means no more problems with alignment and limit screws and a derailleur that can be stood on and still shift properly.
“It’s a big move from SRAM to do this because all the frames have to comply with the UDH standard. We immediately decided to go UDH because it makes so much sense to remove the mech hanger. All the tolerance issues with hangers are just removed.
“Without having to factor in variances in third-party components, SRAM can make everything tighter and more accurate, and also squeeze in the 13th speed.
“Is it going to kill the front derailleur? I’m sure not. A lot of people are conservative, they like what they have, they grew up with it and they want to keep it that way.”
Not the end of the Grit fork
So, if everyone adopts wider tyres, will it make Lauf’s original product, its Grit fork, obsolete? Not a bit of it, says Skúlason.
He explains that wider tyres do a great job of absorbing higher frequency vibrations, but there’s a range of different frequencies that a bike needs to smooth out to be comfortable and fast.
“The Grit works even better with these slightly bigger tyres.
“No suspension fork in the world can ever fight super-fast excitation from surface texture/roughness. While Lauf’s Grit forks are much faster reacting than telescopics, due to their much lower unsprung mass and their absence of friction, a suspended wheel simply cannot move its mass fast enough up and down to deal with washboards at speed.
“For washboards and such excitation one needs to rely on tyres. The Grit fork, however, complements the tyres better than a telescopic fork does, as it kicks in at a higher frequency than a telescopic.
"It’s there to deal with the impacts that are not as high-frequency, but potentially bigger than the ongoing surface texture/roughness, such as rocks or potholes.
“Therefore, if riding skinny & hard tyres on a Grit fork, one gets a ‘dead band’ between the frequency that the hard and skinny tyres can deal with, and the frequency that the Grit can deal with. We've found that running 50-55mm tyres at suitable pressures can bridge that gap up to the Grit.”
