Joly reviewed the 42mm wide SL with an inner tube. He was interested in trying the tire after meeting us at Eurobike.
On the tarmac he had nothing out of the ordinary to report, but for the downhill...
<<In downhill the balance is strangely more mixed: admittedly, the section and the gum of quality offer a grip in curve, as braking, simply phenomenal, but the height of the bike does not fully exploit these assets. It is not the fault of the tire, but if you add the two centimeters due to the cyclo-cross frame and the tire, it is at least three centimeters higher than on a road frame in tire of 25/28 Mm. It starts to do ... In practice, the configuration photographed did not allow me to beat or even approach my reference time in downhill (established with Compass tires).>>
|He noted his 42mm measured closer to 37mm. This was with a narrowish rim with 18mm internal width.|
A 23mm internal width rim should get you closer to 42mm.
On gravel performance:
[On downhill gravel:]
There, it is a new (good) surprise. Once again the flexibility of the tire, and the absence of crampons [knobs] provide much less vibration than my usual tires. If it's obvious on the tar, it's also noticeable on a path. It seems that at equal volume, the absence of crampons provides better contact with the ground.>>
In the end, these Soma Speed 42 mm are the ideal gravel tires for dry conditions.
Their road performances are impeccable, and allow to drive in a group at high speed, as much as on a 150km turn.
But especially their performances along the way are really excellent. The combination of a large volume on a slick tire in my opinion provide the best versatility of a "gravel". Of course some extreme terrain or wet conditions require crampons, but always to the detriment of versatility and performance.>>
The writer makes an interesting note that tires in the 40mm and up range raise the BB of road bikes and CX bikes higher than what they are designed for. And thus you can't corner and steer as confidently, even with the added grip of these tires. Frame makers would need to make frames with lower bottom brackets. This isn't lost on us. We stay pretty conservative on our BB heights. Because ven though we are designing many of our bike to fit 38c and up, we have many customers and bike shops who will outfit our frames with 700x28. This means we can't optimize the BB drop just for the largest tire size, because then the BB height will be too low for more common size tires. For folks wanting wider tires AND the lowest BB height with disc road/CX bike, your main option is to go with a 650b conversion. Second option...a custom frame.