Brucey wrote:according to these tests;
https://www.fietsersbond.nl/sites/default/files/test_schwalbe.pdfThe standard 30tpi Randonneur (#6 on the list) consumes 35.5W (averaged between 25 and 20 kph @ 4bar)
vs the Hyper version (#13 on the list) which similarly consumes 20.5W.
For nominally similar tyres I find it incredible that there should be such a difference, but there it is. I guess between the casing and the tread differences it all adds up.
I agree,but what also surprises me more than anything on that chart is the differences between M/Racer,Kojak and Hypers,30% is a lot
The Randonneur Pro appears to be slightly heavier than the Hyper and some folk say that it is more puncture resistant.
That's a logical conclusion but anecdotally,my experience is one puncture in 3k miles isn't a bad average IMHO,given that I ride quite a bit off road on stony tracks and bridleways.Though the thicker tread of the Rando Pro may be better for people who ride on flint infested roads and tracks.
Note:-Later I'll post a photo of the offending puncture site later to show how bad the gash is in the casing.
I think like the standard Randonneur, it has a thicker tread than the hyper; it might be that this significantly increases the Crr value even if the casing is otherwise similar.
No doubt IMHO.
BTW although the fietserbond tests give the Grand Bois tyre a lower average Crr, I note with interest that they have (unlike other tyres) averaged this over 4 bar and 6 bar values. Then again maybe this is fair because it is a narrower tyre (30-622) than the others in that table.
I'm not too worried about the Crr of the GB tyre being lower as it costs a fortune for a cycle tyre
,isn't readily available in the UK,it's a narrower tyre anyway,and the Crr difference is negligible.So no (£)pain and not much(if any)gain,comfort may be another issue but it'd have to be a significant increase to offset other the considerations
Anecdotally, I have often run tyres (as a pair) until the tread is worn very thin. When fitting similar new ones, I have often felt that the bike was immediately significantly slower; again I suspect that the tread thickness has a lot to do with it.
Again I agree and I've even read reports of people 'shaving' GB tyres with a belt sander to speed them up
Bonkers doesn't begin to describe such practices IMHO.