Aerodynamics / Aerodynamic Cost / Aero parts

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  • It all depends I suppose. In theory you are correct.
    Indoor tracks can be incredibly hot and airless. Outdoors can also be hot too, when you spend all day sitting in the sun and warming up/down on the rollers.

    Longest I am ever on the track for is probably 30- 35 mins, which is enough time to overheat for me (have got into the habit of wearing long sleeved baselayer under my skin suit and heavy gloves due to various crashes). The bottle/bike example you give is concerns dehydration, not overheating, no?
    It's also a sweat thing -not much point being aero if you can't see where the wheels are in a bunch because your eyes are full of sweat.

    Obviously for special events indoors you just want to be as slippery as possible, especially a match sprint, or 200m TT. However, being able to take the ear farings off will be useful for bunch races - I always feel a bit cut off when my ears are covered.

  • is overheating/dehydration not essentially the same thing, as while feeling too hot might not be pleasant, I've not heard of that actually inhibiting performance (obviously the resulting sweating and dehydration does) but would be interested in seeing evidence that it does!

    A fair point about sight being a bit more important for bunch racing/the track in general though! I suspect sometimes slightly dodgy sight isn't a hindrance to time trialling based on the danger and ridiculous kit people (including me) are prepared to try to eek out a few extra seconds...

  • Overheating is more of a distraction than performance inhibiter I guess. Sweat is an issue though.

    Helmet thing is about peripheral vision, but also being able to hear where people are. I've never like having my ears covered though - used to hate wearing full face lids for downhill, you just feel cut off from everything.

  • I'm thinking of splurging on some Chinese carbon clinchers. Given they weigh the same, should I get u-shaped 25mm x 38mm rims or v-shaped 23mm x 50mm rims. They'll both go on a road bike and the front will also do TT duties.

  • U-shaped/toroidals [not quite the same, but that's a minor thing].

  • Y U no 60x27mm ?

    If its a good U shape it'll handle like a shallower rim, and the weight increase is minor. Fewer, shorter spokes innit.

  • 27mm is a bit effing wide no?

  • I make 60s about 90g per wheel heavier than 38s. Not mega massive, but significant. Could you even put 23s on 27mm rims?

  • Can you put 20's on any of them? Thinking super thin slicks like open corsa...

  • 60s will reach the magic 3:1 shape though where you suddenly start winning everything.

    Is the rim 27mm at the brake track? Probably not. If not, yes you can fit 23s.

  • I'm not sure why you'd want to do that?

  • For TT's

  • The brake track on mine are 25. They are 27mm at the fattest point.

    90g for 22mm of more aeros?
    Yes please.

  • If it's toroidal and 27mm wide it'll be best with 23mm (or 25mm) tyres or close.

    [ rash statement – 'test everything' is obvs the ideal situation ]

  • 28 actually.


    1 Attachment

    • titanium carbon rim wu6t.jpg
  • Yes ^ this sort of thing. Quite like Zipp 'Firecrest' 404 rims and should work better with 23mm (ish) tyres than 20mm I believe.

  • @hefty

    @Smallfurry 's 60mm profile is the same as I ride, but mine is the clincher version 18mm internal, 23mm at brake track, 28mm at it's widest point - unbelievable cross wind performance.

    Been riding both 23c and 25c on them - 20c is a no go.

  • I have 25mm brake track / 27mm wide at widest point tubs in 80mm with 22mm veloflex records on - look a bit odd but seem to work well :)

  • In terms of aerodynamics. I think the HED boffins state 20mm on that 28mm rim. Which makes sense as that would match the internal profile.

    Not sure that's practical though.

    My rear 88mm is pretty good in a sidewinder too. Catches the air a bit. But seems stable.

  • Probably fast as hell in a straight line, but I doubt the rim would last very long in a real world scenario.

  • Slipping off curbs, or into cracks, hits the rim. My last rims lasted till the brake track was Cooked regardless though.

    I'd be more concerned With leaning into the Extensions on shitty roads, on a high PSI narrow tyre.

    Which is why I have a 23 on the front.

  • In the GT->Suicide conversion thread there's a pic of a LOOK with a massive gap between the aero seat tube and the rear wheel. I thought this would negate the aero benefit but @umop3pisdn disagrees.

    Please can you point me in the direction of the physics/logic why?

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Aerodynamics / Aerodynamic Cost / Aero parts

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