Tech of the Month April: Silca sealant, Allez Sprint, Pirelli year round race tyres and Mohorič's bike mods

The last four weeks have been big on new tech – buckle in for the best of it

TOTM
(Image credit: )

It's been a jam-packed few weeks in the world of bike tech – if all stories were created equal, it would have been extremely difficult picking out which to run with. Luckily for us, at least, there's been some clear corkers standing up above the rest. 

We've got sealants that claim actually work effectively with road pressures, there's race-ready rubber designed to be tough enough to withstand riding in all seasons, and – naturally – we've got Matej Mohorič's Milano-Sanremo bike mods (more than just a dropper) and the alloy superbike launch that's set comment sections ablaze.

There's plenty going on so let's jump in. 

New four season race tyre: Pirelli P Zero Race 4S

Image shows Pirelli P Zero Race 4S

(Image credit: Pirelli)

The first few weeks of spring might strike as a bit of an odd time for Pirelli to bring out some hard wearing and puncture resistant rubber – but perhaps it shouldn't. 

After all, the P Zero Race 4S are billed as four-season tyres, which does include the summer just as much as the winter. 

The tyres are being pitched at those who want a “racing feeling” year round – whilst also not sacrificing puncture resistance to the extent of a dedicated race tyre. These are also the first model to be 100 per cent made in Italy since the company returned to cycling in 2017, being manufactured in the renovated Bollate plant, 10 km from the Milan Bicocca headquarters.

Currently the tyres are only available in 700c x 26mm and 700c x 28mm with a clincher casing and for a retail price of £61.99 / $84.90. Wider sizes and a tubeless ready version will be coming out later in the season, though.

For more information, you can find our launch story on the Pirelli P Zero Race 4S tyres here.

Silca's 'Ultimate Tubeless Sealant'

Image shows Silca's Ultimate Tubeless sealant

(Image credit: Silca)

Silca's perhaps best known for its lovingly engineered pumps, tools and accessories, but the American brand has now applied that same attention to deal to sealants. 

From its extensive testing of other sealants on the market, Silca found that the best performing sealants used foamier liquids and had lighter particles. Foamy liquids are better at transporting and lighter particles are easier to transport – making them much more effective at getting to the puncture site and then plugging it.

Silca claims the sealant can seal holes up to 8mm, but modestly only advertises this as "+6mm". At road pressures of 80 - 90 psi, Silca claims the sealant can still plug holes up to 6mm in size.

While other brands use microbeads, glitter or walnut shells, Silca found that microscopic carbon flakes were the best performer it tested. Silca gets this carbon from recycled sources and, in being bio-neutral, it shouldn't have a detrimental impact on the environment when it does seal the punctures.  

For more information, you can find our launch story on Silca's Ultimate Tubeless Sealant over here. 

Matej Mohorič's bike mods – not just a dropper

Matej Mohorič dropper posts

(Image credit: Getty / Dario Belingheri)

How could we not mention Matej Mohorič's daring descent of the Poggio, using a dropper seatpost to leave everyone in his wake. 

But that's not the only modification Mohorič brought to the start line. Although his Merida Scultura is nominally only designed for 160mm disc rotors, the team managed to source some adaptors enabling him to run a 180mm rotor on the front – larger than many cross country mountain bikers opt for.

Alongside that, Mohorič was also rolling on "secret bearings", which there's, understandably, not a whole lot of information about. What we have heard is that they utilise some of the technology developed for Mag Lev trains and have to be specially inserted into the hubs.

Bike of the Month: Specialized Allez Sprint

Specialized Allez Sprint

(Image credit: Specialized )

With the hype and the reception, there was only really one bike it could be this month: the Specialized Allez Sprint.

Specialized has pitched this as the world's first alloy super bike, and sure enough, it shares its geometry down to the millimetre with Specialized's flagship Tarmac SL7 race bike. 

If you're after that same handling and on-the-bike position as is used by a clutch of World Tour teams, the Allez Sprint does make for a much cheaper proposition, with the frame coming in at £1,599 / $1,700 compared to £3,750.00 / $5,500.00 for the SL7. 

Typically, quite a unique approach has been taken to the construction. The downtube now blends straight into the bottom bracket, eliminating the need for one separate piece of tubing and removing one of the welds. 

The headtube area has been rethought, too, with Specialized moving the welds there  back along the top and down tubes to make the join a little further away from the points of peak stresses.

For more about the welds and the public reaction to them, you can find our article just here. For our original launch story on the Speicalized Allez Sprint and all of the details about the frame, you can find that just over here.

That's all for this month, we wish you the best of spring riding for the weeks ahead!

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Stefan Abram
Stefan Abram

Starting off riding mountain bikes on the South Downs way, he soon made the switch the road cycling. Now, he’s come full circle and is back out on the trails, although the flat bars have been swapped for the curly ones of a gravel bike.


Always looking for the next challenge, he’s Everested in under 12 hours (opens in new tab) and ridden the South Downs Double in sub 20 (opens in new tab). Although dabbling in racing off-road, on-road and virtually (opens in new tab), to date his only significant achievement has been winning the National Single-Speed Cross-Country Mountain Bike Championships in 2019.


Height: 177cm

Weight: 67–69kg