Ambodach

I'm "over thinking" this as the world of bike tyres is a good deal more complex than 30 years ago when I bought my last bike, and I've got a deal of catching up to do. I've also become somewhat sensitised to pursuing a reasonable knowledge of bike tyres having suffered a puncture on the road within 3 days of buying a £1k8 bike ! d8veh asked about the rim size and I've now measured that as 20mm. Now although there is a caveat on Sheldon Brown's table of tyre v. rim size, the 57mm tyre is very much larger than he recommends for a 20mm rim, indicating that this will lead to wall failure. I suspect again that this is an economy option by Cube. I've been further sensitised by the LBS where I bought the bike (and was initially impressed with their professionalism) being unable to advise on a suitable on-road tyre because "this is a 29er bike", and recommending that I just raise the pressure in the tyres. As the particular tyres are already poor for road traction, my thinking is that would be a particularly risky thing to do. I hope this will explain why I am "over-thinking". And actually since when was 10mm = 1/4" so please don't troll me unless you can get your facts right.

Thanks for the comments and assistance guys. I looked up Sheldon Brown on tyre sizes http://www.sheldonbrown.com/tire-sizing.html and there's a chart there relating rim width to recommended tyre width. The nuisance is I'll have to take a tyre off the get the rim width - hey-ho. There's probably some normal value but I don't know it and with the sloppy MTB tyres I've already got, I'll be easier enough to drop the front wheel and get the digital calipers out. However I'm not any further forward really on the question of 'wired' and 'folding' tyres - is one better than the other? Lighter? Easier to take off the rim? price? - etc., etc. Some of the Marathon Schwalbe tyre range are available in both, some wired, some folding - and then the Nobbly Nic MTB can be got in either.

I found Hopbackguy's post of a week or so ago about tyres - in his case he was going up from a road tyre to an off-road tyre on a 28" in wheel. I'm going in the opposite direction !! I've just bought a Cube electric MTB and having ridden about 20 miles only on roads on it, and collected my first puncture in many years, I'm not at all impressed with the tyres fitted. They are Schwalbe Racing Rob and Tough Tom, and judging by the retail price, the tyres are one area where Cube have cut corners on the price. Maybe this is a standard practice with bike manufacturers but it's not one that endears them to the purchaser. So the tyres that are on are an MTB type which I find are rated with poor road traction and have a poor grade in protection, so I'm now looking for a road /trail tyre like Hopbackguy. I've done a bit of homework on alternatives but in two areas I need assistance. 1 The existing tyres are marked as 29" x 2.25" and 57 x 622. There are a number of tyres that my homework suggest have good rolling resistance, good road traction, passable off-road and good for protection, but they are all 622 and either 40, 42 or 47. The question is - will these go onto the rims currently carrying the so-called "29er" type tyre. 2 What is the difference between 'wired' and 'folding' type tyres? Many thanks for any assistance Rob

Many thanks for that. I did go back over 10 pages of postings doing a CTRL F search for 'torque' and didn't find anything; that was of course in the post headers and not in the text. I couldn't find a forum search facility as that would have picked this thread up. That solves my puzzlement. I'll pass the link onto the LBS who should have done some homework on this topic as they were inevitably going to get someone coming in with the query about 250W power limit but a 2 to 1 ratio on torque output.

Can someone tell me - because the bike shop can't as yet - how one e-bike can have a power unit which is 250W and gives out 40Nm of torque and yet the next door bike, albeit a bit more expensive, is also 250W but has a torque rating of 80Nm. These are both Bosch powered machines. I'm was an electronics engineeer for 45 years and know enough about engineering to know what torque is and also enough about electric motors to know what 250W means, but I am puzzled as to what element of technology allows a doubling of an output parameter for seemingly no increase in input power. And again because I'm not a 'oily' mechanical engineer, what impact on cycling does this extra torque give ? Thanks Rob