# 23 vs 25c TUBULAR for racing



## adam_mac84 (Sep 22, 2010)

I understand the 23 vs 25 concept for rolling resistance etc... 

Is there a benefit from 25's in tubular, since the 23c can be run a bit lower without pinch flats (the reason for tubular vs clincher)?

I want to glue up some tubs for racing this year, crits, RR, and a 75% pavement 25% gravel race. The 25's would be great for the gravel race, but how about the others? I currently ride 23's on the road because i have them, but i own and occasionally ride 25's on my CX bike, and like that I can go a bit lower, but it's my first set of tubular ROAD tires, so looking for opinions.


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## adam_mac84 (Sep 22, 2010)

and, anyone mount 23c tires on a 23mm rim? (major tom or similar). I have escapes and toms available


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## cxwrench (Nov 9, 2004)

it really depends on the shape of the tired bed of the particular rim you have. for example, we've been finding that 23mm (not 'c') tires don't work too well w/ Zipp 303 and Bontrager Aeolus carbon rims. the new rims are soooo wide you have to be really careful w/ the number of layers of glue and how you mount the tire. i'm going to try some 25mm tires on a Bontrager rim next week and see how they work. i think the 23mm tires are too narrow for the new rims. i think 23mm tires will be fine on the major tom, i've never noticed any problems w/ them...usually using vittoria cx and zipp tangente(made by vittoria).

oh yeah...i'd probably make the 23/25mm decision based on how much you weigh, and how 'heavy' you ride. if you think you'd pinch flat a clincher on the dirt roads you'll be riding, then go 25mm. it won't slow you down at all, and may actually let you go faster on certain terrain.


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## gordy748 (Feb 11, 2007)

Leonard Zinn has a couple articles that prove the 25s have less rolling resistance than the 23s, though some wheels are designed especially for 23s so the wind turbulence caused by adding 25s saps more power than the rolling resistance benefit. We are talking fractions of watts lost, though.

Last year I went from 23 clincher to 23 tubular to 25 tubular (I'm average height, now 180 lbs). I changed tubbie brands so it's hard to say whether the size difference is really that different. I don't see any difference in the speed during shorter rides but my butt appreciates the extra mils over every bump. This helps me in longer rides as I stay fresher longer.


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## GGW (Jul 13, 2008)

cxwrench said:


> it really depends on the shape of the tired bed of the particular rim you have. for example, we've been finding that 23mm (not 'c') tires don't work too well w/ Zipp 303 and Bontrager Aeolus carbon rims.* the new rims are soooo wide you have to be really careful w/ the number of layers of glue and how you mount the tire. i'm going to try some 25mm tires on a Bontrager rim next week and see how they work.* i think the 23mm tires are too narrow for the new rims. i think 23mm tires will be fine on the major tom, i've never noticed any problems w/ them...usually using vittoria cx and zipp tangente(made by vittoria).
> 
> oh yeah...i'd probably make the 23/25mm decision based on how much you weigh, and how 'heavy' you ride. if you think you'd pinch flat a clincher on the dirt roads you'll be riding, then go 25mm. it won't slow you down at all, and may actually let you go faster on certain terrain.


Can you explain a bit more about the gluing process on these Bontrager ? Just received a pair of D3 and i'm about to install 25 mmm .I've contact Bontrager and they recommend minimum 23 mm ,25 or 27mm.Forgive my broken english .:blush2:


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## cxwrench (Nov 9, 2004)

GGW said:


> Can you explain a bit more about the gluing process on these Bontrager ? Just received a pair of D3 and i'm about to install 25 mmm .I've contact Bontrager and they recommend minimum 23 mm ,25 or 27mm.Forgive my broken english .:blush2:


i do 2 coats on the tire, letting them dry between coats. *re-stretch the tire after the glue is dry*. 2 coats on the rim, letting them dry between coats. last coat on the rim is pretty thick, mount the tire immediately. partially inflate, get it straight. let the air out, and push the base tape into the bed of the rim. inflate to 50-60psi (3.5-4.0bar) and let it dry overnight.


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## GGW (Jul 13, 2008)

cxwrench said:


> i do 2 coats on the tire, letting them dry between coats. *re-stretch the tire after the glue is dry*. 2 coats on the rim, letting them dry between coats. last coat on the rim is pretty thick, mount the tire immediately. partially inflate, get it straight. let the air out, and push the base tape into the bed of the rim. inflate to 50-60psi (3.5-4.0bar) and let it dry overnight.


Thank you it's really appreciated


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## adam_mac84 (Sep 22, 2010)

well, the LBS had some Continental GIRO 22mm tires cheap, so my buddy picked up a pair.

I stretched and inflated one of them over my major tom.

Tire measured 21.8mm on calipers
Major tom 22.5mm (must take off .25mm of the 23mm rim width in the machining process)

that means there is technically .350mm of 'rim overhang' with these tires... should this be a problem? In my mind it seems like it should pose a problem,but I guess the gluing surface is still being glued.

I'm gluing up the tubulars primarily for 1 race, (gravel/paved), so I would prefer not to build up a new set of wheels just for tires, and the price on the Giro through our shop was awesome.

What do ya'll think?

I guess i could rip the tufo's from my wife's training wheelset (GL 330/ULTEGRA 36H), BUT it sure is nice to think about racing my 1530g major toms (light in my world lol)


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## pedalingsquares (Feb 14, 2009)

*New Bontager wheels*



cxwrench said:


> it really depends on the shape of the tired bed of the particular rim you have. for example, we've been finding that 23mm (not 'c') tires don't work too well w/ Zipp 303 and Bontrager Aeolus carbon rims. the new rims are soooo wide you have to be really careful w/ the number of layers of glue and how you mount the tire. i'm going to try some 25mm tires on a Bontrager rim next week and see how they work. i think the 23mm tires are too narrow for the new rims. i think 23mm tires will be fine on the major tom, i've never noticed any problems w/ them...usually using vittoria cx and zipp tangente(made by vittoria).
> 
> oh yeah...i'd probably make the 23/25mm decision based on how much you weigh, and how 'heavy' you ride. if you think you'd pinch flat a clincher on the dirt roads you'll be riding, then go 25mm. it won't slow you down at all, and may actually let you go faster on certain terrain.


 CXWRENCH.. Question, I have a set fo D3 Aelous coming tomorrow. I will be using the 7 on the back and the 5 on the front. You were talking about the rim bed being quite wide. Did you mount up some 25's on those yet and if so how did those work.

I have some Vittoria Evo 25's arriving today to starting gluing. I am employed with a Trek dealer, so I can get better pricing on the XXX tubulars but if the 25's work better on the rims, that is the direction I'm going.

Thanks for the help and I hope the wheels work out great.


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## kbwh (May 28, 2010)

Coincidentally I just glued a Veloflex Extreme/Carbon combo, both 22mm nominally, on a set of Zipp 303 (the "for pavé" version that came out before the current Firecrest). I didn't find the tire bed too wide for these tires at all, following my normal gluing practice.


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## cxwrench (Nov 9, 2004)

kbwh said:


> Coincidentally I just glued a Veloflex Extreme/Carbon combo, both 22mm nominally, on a set of Zipp 303 (the "for pavé" version that came out before the current Firecrest). I didn't find the tire bed too wide for these tires at all, following my normal gluing practice.


the 'old' toroidal 303's were no problem. the 'new' firecrest 303's are wider than the 404 and 808...not a big problem, you just need to be aware of what can happen.


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## ergott (Feb 26, 2006)

@cxwrench

Is it the radius of the tire bed that is too large or just the rim width? Zipp states that their rim was designed around a 23mm tire.

I have no problem using 23mm tires on the Enve Smart rims. The radius matches up.


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## cxwrench (Nov 9, 2004)

they sit on the rim ok, but you need to use a pretty think last coat of glue, and push the tire down into the rim bed really well, and on the narrower rims it seems like pumping up the tire does the trick by itself. i need to try them w/ wider tires, but since zipp supplies us w/ 23mm...it'll have to wait.


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## GGW (Jul 13, 2008)

I wrote to Bontrager about recomended tyre width and here wath they answered .If this can help .

Thanks for writing in. The smallest size tire the Aeolus D3 wheels will accommodate is a 700x23c tire. Any smaller you will risk damaging the rim. We tested the tires in the wind tunnel with a 700x23c and a 700x27c tire and both tire widths performed extremely well with the 23c tire having slightly less drag. Depending on your riding style and preferences, I recommend using a 23, 25, or 27c width tire.

My freind just bought a pair of enve smart system and they recommend him the same tyre width. 23mm that is


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## cxwrench (Nov 9, 2004)

pedalingsquares said:


> CXWRENCH.. Question, I have a set fo D3 Aelous coming tomorrow. I will be using the 7 on the back and the 5 on the front. You were talking about the rim bed being quite wide. Did you mount up some 25's on those yet and if so how did those work.
> 
> I have some Vittoria Evo 25's arriving today to starting gluing. I am employed with a Trek dealer, so I can get better pricing on the XXX tubulars but if the 25's work better on the rims, that is the direction I'm going.
> 
> Thanks for the help and I hope the wheels work out great.


i haven't mounted any 25's up yet, but i'd wouldn't hesitate if i were you. i'm sure they'll work just fine.


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## MattSoutherden (Jun 24, 2009)

23c or 25c? Crikey, them's some small wheels, bro.


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## cxwrench (Nov 9, 2004)

MattSoutherden said:


> 23c or 25c? Crikey, them's some small wheels, bro.


with the number of tire labels out there that have the 'C' in the wrong place, it's no wonder people get confused. 
i know only a few people will read this, but what Matt and i are talking about is this...

rim sizes use the 'number + letter' designation. like: 700 C, or 650 B
tires sizes should be the same, _plus_ the width of the tire in MM, like: 700C x 25mm

700 x 25C doesn't make sense. get the idea?


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## GGW (Jul 13, 2008)

Just glued on last week a set of Vittoria cx 25mm on my D3 5 rims folowing CXWrench advices (thanks again ) and all went very well . the 25mm match the rims very nicely .Went for a 100km in the hills and they are perfect on the climb and descent ,great wheels so far .


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## cxwrench (Nov 9, 2004)

GGW said:


> Just glued on last week a set of Vittoria cx 25mm on my D3 5 rims folowing CXWrench advices (thanks again ) and all went very well . the 25mm match the rims very nicely .Went for a 100km in the hills and they are perfect on the climb and descent ,great wheels so far .


glad to hear that worked out for you so well, great job!


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