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23 mm vs 25 mm--all rims or just new, wider rims?

Keith WickKeith Wick
in General Training Discussions

With all this talk about 25 mm tires having less rolling resistance and being faster than the 23 mm tires, does that apply to all rims or to just the newer, wider rims that are being made?

trying to decide whether to race the 25's or 23's at IMMT.

Comments

  • Brad MarcusBrad Marcus
    Funny you bring this up. Just prior to IMLP, I ordered some new tires and mistakenly ordered 25mm while I meant to order 23mm's (Conti GP4000s). I ordered them through Amazon Prime and was trying to figure out how to do a return when I figured I'd call the wheel manufacturer of my rims (Zipp). Zipp told me that you will save 2-3 watts by going with 23mm tires on the front and 25mm on the back vs all 23mm or all 25mm. I ended up not changing my tires pre-race because I got spooked in doing so too close to raceday, but it's good to know and I'll try the setup on my next change.
  • Keith WickKeith Wick
    @ Brad--are your Zipp's the older version or the new, wider Firecrests?
  • Brad MarcusBrad Marcus
    Firecrest 404's. Bought them new in 2013.
  • zwubazwuba
    I mounted a pair of brand new GP4000SII 25mm on my FLO wheels yesterday ... looks FAST image
    Had 23mm before which were 25mm width when mounted. The 25mm tires also gained 2mm when mounted.
    Pretty sure 25mm isn't the best choice for all narrow rims (<20mm)
  • tim cronktim cronk
    @Keith... Timely post... I too mounted some gps4000s 25's on my FLO 30/90's yesterday.... Went for a 30 mile ride... Nice ride... Faster? I Cant tell .... I think rim width is very important to the tire debate.... Putting a 23 on a 24wide FLO rim makes it look like a 25 on a skinny rim .... I have been very happy with the FLO wheels and have lowered my PSI from 105ish to 90ish , offering a much better ride and no loss of speed...

    From what I understand the 23's are more aero and the 25's have less rolling resistance? I do think I will continue to race with 23's ... I did run a set of Force/Attack 22/24 tires on my old Reynolds CC's and I liked them, they were fast , but I didnt like the skinny front tire for handling (infact that was the tire I had on when I crashed and broke my collar bone , still not sure but I think a crack in the road was the culprit among my own stupidity). Larger tires go over our ever declining road conditions much better.

    I'm in the process of choosing/buying a road bike and plan to run wide rims with 25's .... Probably FLO 30's... But it more in the theme of comfort and handling than speed.
  • robin sarnerrobin sarner
    Other issue is if the wider tires will fit your bike frame.
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