The reply to the query could seem apparent. With no air to flee from them, there’s no likelihood that stable tyres, additionally typically known as airless tyres, will ever get a puncture, avoiding an issue that has been the plague of cyclists ever since John Boyd Dunlop patented the pneumatic tyre in 1888.
Strong tyres do thrive on kids’s bikes, though even right here pneumatic tyres – these crammed with air – are fitted to lots of the greatest youngsters’ bikes, even steadiness bikes for the youngest kids. Pneumatic tyres take over virtually fully as soon as bikes are designed for teenagers of round three-years -old.
Strong tyres have by no means been a well-liked selection for bikes designed for adults, regardless of occasional appearances on leisure fashions, and positively not for efficiency bikes. The apparent purpose for that is ‘experience high quality’. Adults experience quicker than three-year-olds, they need to take pleasure in grip and luxury in addition to puncture safety. Can stable tyres ever meet these wants?
A query of suspension
Air crammed tyres may danger puncture, however they do present consolation, management and grip
(Picture credit score: Future)
Tommaso Cappella, Product Specialist at Vittoria explains that the tyre performs two principal duties: to supply traction and to insulate the car from the terrain.
“It’s the solely a part of the bicycle in touch with the bottom; this implies it mainly acts as a suspension which optimizes power switch, securing the transmission of driving forces whereas additionally absorbing the roughness of the terrain.
“The air contained in the tyre works as a spring permitting the tyre to deform with minimal power loss, leading to a extra environment friendly energy switch and management of the bicycle,” he factors out.
Air performs this job very effectively, a stable core to the tyre much less so. It’s comparable with MTB suspension, the place air shocks are in the primary the go-to answer.
“If we take away the air from the tyre and substitute it with another materials, this materials will deform rather than the air, consequently rising the power absorption of the system, leading to larger rolling resistance,” Cappella continues. “In brief these are the the explanation why a stable tyre can’t present the identical consolation, grip and effectivity of a pneumatic tyre.”
Once I examined a set of 25mm stable tyres from South Korean model Tannus just a few years in the past, the distinction in rolling resistance was important, chopping over a mile per hour off my using pace. It wasn’t simply this although; the expertise was a lot much less snug than using a motorbike with pneumatic tyres, even slim ones with tubes.
Tannus acknowledged that the stable tyres examined had an equal deformation to a pneumatic tyre pumped as much as over 100 psi, which is far larger than regular experience pressures, even only a few years later. However whereas older stable tyres had questionable grip, the Tannus tyres I examined had remedied this each on dry and moist roads.
The distinction in experience consolation is simply prone to have elevated with the widespread adoption of 28mm or wider tyres and more and more fashionable tubeless methods operating at decrease pressures, each of which assist to clean out street imperfections. Tubeless tyres additionally remove the frictional losses which happen between the tyre and interior tube once they deform, which has been proven to extend system effectivity.
All of which involves the nub of the issue with stable tyres: there are newer applied sciences on the market which, for almost all of cyclists, present a greater possibility.
Roll flat with out the rolling resistance?
Foam liners, like this one from Vittoria, supply a extra compliant soloution
(Picture credit score: Vittoria)
One other new expertise that appears to offer lots of the advantages of stable tyres with out the downsides is foam tyre inserts.
A few choices are Vittoria’s Air-Liners and the Cushcore system. Tannus too has pivoted to producing liners alongside its stable tyres. All three manufacturers’ inserts are fitted inside a traditional pneumatic tyre and can be utilized when operating tubeless.
Cushcore is principally geared to MTB and gravel riders, though it states that you should utilize its gravel insert with tyres from 33mm large, placing it inside the realm of tyre widths of many fashionable street bikes. Each Vittoria and Tannus promote inserts for street bike tyres in addition to for gravel and MTBs.
Whereas the Air-Liner and Cushcore inserts and Tannus’s tubeless insert sit within the wheel rim mattress, Tannus’s insert for tubed tyres is 15mm thick, sits under the tyre tread and cradles the interior tube, doubtlessly decreasing the possibilities of a pointy object penetrating by to the tube.
Apart from Tannus’s tubed tyre insert, somewhat than rolling on the insert, in regular situations there’s some air between your insert and the bottom, which the manufacturers say ought to permit you to run decrease tyre pressures with out tyre squirm and the danger of pinch flats, rising grip, notably when using off-road.
So these inserts do not do something to guard your tyre from a puncture, however when you do get a flat they’re claimed to offer get-you-home functionality.
We’ve but to check out any of those claims ourselves at Biking Weekly.
Bicyclerollingresistance.com has examined each the Air-Liner and Cushcore inserts in a 40mm gravel tyre and located that they add little further rolling resistance right down to pressures as little as 1.2 bar (18 psi). Drop your strain under this and also you begin to experience on the liner, and the issues of a completely stable tyre emerge.
Cappella says that Vittoria’s analysis confirms this: “If correctly designed by way of materials and geometry, the insert lets you maintain the air contained in the tyre whereas not being concerned (or with negligible impact) within the rolling deformation throughout regular use, on the identical time enhancing the damping and the management within the lateral deformation, leading to larger efficiency and security, by decreasing the possibilities of punctures.
“Final however not least, the Air-Liner insert lets you experience brief distances on a tyre with out air, till the subsequent service level (or till the workforce automobile arrives).”
Tyre liners add a bit weight to your wheel: round 50g per tyre for the Air-Liners and 120g for Cushcore inserts, however when you’re fed up with flats, however nonetheless need the advantages of a pneumatic tyre, this is likely to be tolerable.
Will stable bike tyres ever actually be a great answer to punctures?
“No”, says Cappella.
“Backside line, we imagine the way forward for sportive tyres continues to be pneumatic: that is the most effective performing kind of tyre; whereas stable tyres can scale back to zero the prospect to puncture, they can not present the identical efficiency, management and luxury of a pneumatic tyre.”
