olympic mtb course your view?
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njee20 wrote:Aye the weight difference is more pronounced on road rims too, as the tub rims can be a very light construction, whilst clinchers need a lot of reinforcement to support the tyre bead at high pressure.
It's the opposite on the MTB - rims need to be tougher, and the bead hook doesn't need to be as strong. It's why I don't quite get it myself, but would like to try some!
They a less prone to pinch punctures which when you are bouncing over rocks etc are probably quite likely. Pinch punctures are also pretty much impossible to repair with a cannister as the holes are too big. So for XC racing tubs make perfect sense really (as long as they are stuck on properly).0 -
Tubeless has the same benefits, in fact you're more likely to pinch flat a tub than a tubeless tyre as they've still got a 'tube' in them. Seeing as virtually none of them are riding conventional tubes that's a moot point.
Changing tyres to suit the condition are also pretty common in XC racing, which is an inherent issue with tubs lest you have 5 sets of wheels. Panacea for road racing, less so for XC!
I'm sure the ride quality is better, and some rims are lighter (AX Lightness as used by some of the riders are 230g, the DT ones used by the Swiss guys are very light too), but for the sort of mid-range FRM rims and Racing Ralph HTs, where you add weight, expense and lose flexibility I'm not so sure!
I guess it's a pro vs mere mortal thing!
Do we know what rims Annie Last was running?0 -
So the stickers say anyway... ;-)0
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What do you mean? The vast majority of the Spring Classics used to be ridden on Ambrosio box-section tub rims, but they'd bring nothing to a mountain bike race, being narrow and heavy.0
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I'm really confused by the point you're trying to make? 29er tub and 700c tub rims aren't the same, as with clinchers road rims are narrower, not aware of any of the mountain bikers on 29ers (least of all Miss Last on 26" wheels) using road rims for mountain biking.
Yes carbon rims have been far more prevalent in the classics, Roubaix has been won on carbon rims for 3 years now isn't it? Again though, not the same as the MTBers are on.0 -
Neither of us have any idea about what? I'm really confused!
None of the riders in the Olympics were using road rims! That's very obvious, if nothing else the road guys are all going toward much wider rim profiles - Zipp Firecrest, Bontrager Aeolus etc, and all their rims have braking surfaces.
Annie Last was obviously using the Superlogic MTN wheelset, my comment was tongue in cheek. The Swiss guys have certainly been using some DTs that are significantly lighter than stock, presumably still the case now Schurter is on the 650B wheels, as his rims are obviously not available after market. The Cypriot(s) were on AX Lightness, I forget what else I noticed.
700c and 29er rims are both 622 ETRTO, but the rims aren't really interchangeable, clincher or tub.0 -
I just have no idea what you're talking about :?0
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You're not racing in the world cup ;-)
You need to be wary of pressure limits on those - 120psi in a Crest could end badly! Conversely I'd not put my faith in Alphas to last endless rock gardens!
I did say "not really" interchangeable!0 -
I'm not fat, so I'm not anywhere near 120psinjee20 wrote:You're not racing in the world cup ;-)
You need to be wary of pressure limits on those - 120psi in a Crest could end badly! Conversely I'd not put my faith in Alphas to last endless rock gardens!
I did say "not really" interchangeable!
And there's no pressure limit on tubed setups on Stans rims.
And I don't understand the first point. 26" rims "aren't really interchangeable" with one another if you replace a DH rim with a XC717, because the use of it is inappropriate. You can say that for anything. But 700c and 29" are exactly the same. A 29" rim with a given internal width is completely interchangeable in a "will it fit" sense with 700c rim of the same width. They're exactly the same size. The world cup has nothing to do with it.
"X might not be suitable for XC racing" is an entirely different point.
And what about this from the conversation following on from photos of one of the race bikes:bails87 wrote:Njee: Could they be road rims?
viewtopic.php?t=12871622&p=17798023njee20 wrote:Very possible. They look to be non-eyeletted, which suggests Stan's. Got some photos of Sam from yesterday, will have a gander if there's any more clues (if he raced on them!).0 -
"X might not be suitable for XC racing" is an entirely different point.
Surely that is the point though? You don't see rims marketed as 'ETRTO 622mm rims for road or MTB use", they are marketed as 29er/700c. Marketing solely perhaps, but at the extremes of use they're not really interchangeable, although yes there's a lot of grey area in the middle. ENVE/AX Lightness/Ritchey/DT Swiss etc all do 29er tub rims (which is what was being discussed) and 700c tub rims, they're not the same product.
The inference in this instance, I think, from ddraver was that some of the MTBers on carbon tubs may have been using 'road' rims, which I'm very confident that they weren't. Sam Schultz did appear to be using an aluminium clincher rim, which could have been a road one (it's not), they're not pared down to the same extent - you're talking about a 400g+ rim vs a 220g one. I'd use Alphas on a 29er MTB before I'd use Zipp 303s, for example.
So... there's 2 points here:
1. Were any of those on carbon rims at the Olympic race using 'road' rims - no and I'm not aware of anyone ever doing so at the top level, whilst there's lots of 'black box' type testing programmes I don't think there's the crossover here. There is of course development in 29er rims, but I don't think it consists of using road rims.
2. Could one use a 'road' rim for MTBing? Yes, although they come up narrower than most MTB rims, something like an Open Pro will be alright, although quite why you'd do it is something else. Why don't we see people using Alphas on MTBs? Lighter than most 29er rims? I guess durability.
How many times have I contradicted myself!?0 -
I was just addressing the interchangeability point. A 29" rim can be used for 700c tyres and vice versa. If it's being used somewhere inappropriate then it's a different point. I'm not fussed about the olympic specifics, or "olympicifics"
I didn't think alphas were much lighter than Crests tbh, I looked at them when planning/pricing my CX build.
Just checked, alphas are 5g each heavier than Crest 29ers, and I've weighed the Crests so know the claimed weights are actually a bit high.0 -
Look pretty cool and challenging on the body if done at speed0
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Last round of the NPS series is there, August 18th next year, for anyone who fancies a crack at it!0
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Mmm, it'll be interesting to see what happens with entry numbers etc.0
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Have you signed up to ride the course in october before any of the chicken runs are put in?
Also you have the MSG race there next year too.0 -
I've not, no. I'm not that fussed to be honest. I look forward to racing on it in whatever guise it ends up, but I'm not driving all that way to ride 2.9 miles just in case they change 50 yards of it!0
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LOL yeah i get your point, its not too far for me so i have nothing to loose, plus i'm intrigued to be guided around a race track
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bails87 wrote:
*waits for all the people who said it was really easy to sign up*njee20 wrote:Last round of the NPS series is there, August 18th next year, for anyone who fancies a crack at it!
I will defo be doing it....whatever format it's in.... as will my mrs (neither of us thought it looked easy BTW) 0 -
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I do suspect people will come though, and be bitterly disappointed that it's 20 minutes of riding! With good reason!0
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very true, not enough to travel for an hour plus to do a 20 min lap.
bit like Redgbridge cycling centre, i think it takes me 4 mins to do a lap there 0 -
Thought i'd bring it Alive!
Whos racing there this weekend then?I do science, sometimes.0
