I did my research on these a while back and found they actually increased rolling resistance.

fools

Hmm, what’s your source for that? And compared to what? Did a wee bit of googling and all I can find is road tube comparisons.

It’s not a concern for me (though bloomin bursting for no reason is!) but it’s interesting

I’ll try to find the source for it but it was compared to various XC tyres.

Might be a bit of a pain to find as I was reading German forums – you know what they’re like for chartzzz and proofs. Even found a review the other day testing the G-forces various downhill helmets impart on the user. You never see that in British mags.

I had to double check the date.

FOOLS GOLD.

German mags seem quite into their pseudo-science, it’s interesting reading but sometimes when you take a step back it’s obvious nonsense- like Bike mag melting an icetech rotor in their test rig, which it seems is something that’s never happened in a bike, but still drawing conclusions from their wonky test. Likewise g-force alone is meaningless without dwell times, and the relationship between those 2 and the outcome on squishy humans isn’t something simple enough to cover in a bike mag review- but g-force is a nice simple “bigger/less” number that seems meaningful even when it’s not.

Still, it’s better than “It didn’t fit me therefore I’m taking points off” a la UK press 😉

By dwell time I’m assuming you mean how long the g-forces were applied for. I’m also assuming that if G-forces remained the same for each impact then the helmet with the lower g rating would see the energy of the impact spread out over a longer period of time.

Not a physicist, so I wouldn’t mind knowing why dwell time is so important in a controlled test.

Basically, a lower force for a longer time can be as damaging or more to soft tissue. There was quite a bit of literature on this for motorbikes when the SHARP tests were introduced, lots of CEN vs Snell comparisons.

My own knowledge only goes as far as knowing it makes a difference, not exactly what the difference is… But everyone but Snell seems to agree it’s significant, and that testing without it doesn’t make any sense.

Any update on those tubes, NW? Did they end up back at Merlin?