Ideal Tubular Tire to Rim size?

Everything about building wheels, glueing tubs, etc.
Zoro
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by Zoro

For tubular glue on only, what is the ideal tire width vs. rim width ratio - 1:1? What is too narrow? Can the tire be narrower than the rim? Feels like a 22 wide tire would be good on a 22 wide rim. There are 25mm rims - should they have 25mm tires? Can a 20mm rim have a 25 mm tire?

I love the Veloflex Rocord 28 (22mm), but seeing these FMB 25 silks that look good, although heavier. The rim coming is 25mm.

Opinions please.

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ergott
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by ergott

Ideal for what? Discussing rim width in a vacuum isn't helpful. For ride quality, I prefer shallow, box rims. For aerodynamics, the shape of the rim is more important than simply making the rim wider. Rims from Zipp, Hed, Enve et al are all 25mm and wider, but it's the transition from tire to rim sidewall that's important. Rim depth also needs to be considered.

Zoro
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by Zoro

Racing - Crit and road.
Last edited by Frankie - B on Mon Nov 25, 2013 10:23 pm, edited 1 time in total.
Reason: deleted the quote.

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ergott
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by ergott

Keep in mind rim width doesn't effect a tubular tire like a clincher. The tubular tire will remain relatively the same regardless of the rim it's glued onto.

Zoro
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by Zoro

I just ordered the FMB competition CX silk in 22.5 (told they are more like 23) and the 25 so I'll mount on the new rim without glue and see.
Last edited by Frankie - B on Mon Nov 25, 2013 10:24 pm, edited 1 time in total.
Reason: no need to use the quote function. you are writing a reply. ;)

Geoff
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by Geoff

@ergott, well, if you run a really narrow (18 or 19mm) TT or track-type tire on a wider rim, you may have a problem with getting a really good glue bond to the outside edges of the basetape, which is a crucial part of a secure glue job. Same goes for running a 'conventional'-width rim and a wide (30 or 32mm) 'cross tire, but at least you can run 'Belgian' tape and it seems to work just fine.

@Zorro, are you running the FMB's on a set of deep Hed rims? If so, you should be fine. The 25mm tires will work great on the back and should protect you from pinch-flatting with the deeper rim. The 22mm up-front works just fine with those rims.

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LouisN
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by LouisN

Zoro wrote:Racing - Crit and road.


I would be scared of running a 20-21 mm tub on a deep channel 25 mm wide rim.
Don't know if it can be dangerous, if the rim can touch asphalt on high speed 90° turns in crits...

Louis :)

Zoro
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by Zoro

These are Mercury M5T - 25 wide. My kid is < 140 # and has ridden OLD Nibble FLYs and Easton EC90s with Veloflex Record 22 - about 120-130 PSI and most races are under 100K. As he is racing longer, and we need new wheels the Mercury wheels look good. They are supposed to be stiffer too for sprints - which matter, and pretty aero, which also matters for his type of riding. The whole 25mm does give less tire selection and they are heavier - tire and rim.

Its all ordered now - cc is charged (kicked in the fraud warning system).
I'll post pictures of the 22.5 and 25 mounted (unglued) when they get here.

Geoff
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by Geoff

Hmmm. I havent riddent those wheels, but saw them up-close at ToC last season. The look solid to me.

I am a bit lighter than your boy, but would still not recommend running the tires that hard. I would recommend 100/110 (front/rear) for road racing and less if the conditions are wet.

Zoro
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by Zoro

From what I've read - lower pressure unless you're Spanish. I guess the 130# Spanish riders like it at 130psi.
My kid is trying to learn Spanish - maybe the pressure will help. I will likely run them higher because he notices it and requests it.

http://velonews.competitor.com/2012/05/ ... ire_218011

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Tinea Pedis
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by Tinea Pedis

Might explain why Euskaltel are so poor at keeping their bikes upright...

Zoro
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by Zoro

Here he was 65lbs, 8 years old in the picture below. Tubulars were at about 65 psi. As these were Tufos, 65 psi and flat feel about the same.

We went to Vittoria Crono EVO CS for about 5 years, inflated to 100, then the Veloflex Record 22 for the past 2 years running @ 120+

Image

Geoff
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by Geoff

Yeah, 130+ psi in a tubular makes no sense. You are doing all that work to get a fast, supple tire. For a light rider, there is no reason (i.e., to prevent the tire from bottoming-out on the rim and risking a pinch-flat) to run them that hard. That goes double for a high-volume rear. You can run 30 psi less without materially increasing the risk of a pinch-flat and have the benefit of better traction, better comfort and a faster tire.

Great pic. My boy will be turning 6 soon and he will fit 'proper' wheels soon. What bike is that?

Zoro
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by Zoro

Geoff wrote:...
Great pic. My boy will be turning 6 soon and he will fit 'proper' wheels soon. What bike is that?

That was an eBay Leader frame with parts from the discard bin. The hardest thing to find will be narrow HBs and Short cranks and short reach brakes. I think those were 155 as I recall.

mattr
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by mattr

Are they 25mm wide at the brake track, or 25mm at widest point?
I've only seen a handful of the modern wide tubs, but they were all bulged below the brake track. Or tapered out from the tyre channel.
So the bit where you glue is still only around 19/20/21mm wide.

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