Tubulars and rim width
08-20-18, 05:37 PM
#1
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Tubulars and rim width
I am delving into the world of tubulars and I am having a hard time figuring this part out. tubular size to rim width. Is there any rule of thumb for rim width vs. tire size with tubulars? About all I could find is skinny rims may not safely glue well to wider tubulars, but nothing on how skinny the rim or how wide the tire. My wheels have Sun Mistral rims (~18.5mm?), and I plan on using some 23mm tires to start with but I run 25mm tires on my clinchers.
08-20-18, 06:54 PM
#2
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I have glued and successfully run 30mm tubulars on very narrow old-school rims. If your glue job is good, then there is more than enough surface area for proper adhesion.
Keep in mind that much of the trend towards fatter tires and now rims are inherent to the fundamental problems in the clincher rim profile. Clinchers need more air volume than tubulars due to propensity of clincher rims to cause pinch flats. So bigger (heavier and less aero) tires. Which requires wider (ditto) rims.
All of this of this is avoided with tubulars. Yet another of the numerous advantages with tubulars.
Keep in mind that much of the trend towards fatter tires and now rims are inherent to the fundamental problems in the clincher rim profile. Clinchers need more air volume than tubulars due to propensity of clincher rims to cause pinch flats. So bigger (heavier and less aero) tires. Which requires wider (ditto) rims.
All of this of this is avoided with tubulars. Yet another of the numerous advantages with tubulars.
08-20-18, 07:02 PM
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I have various that are mostly around 20mm,
but the narrowest (18.8) have the widest tires (33mm CX).
I wouldn't worry about it.
but the narrowest (18.8) have the widest tires (33mm CX).
I wouldn't worry about it.
08-20-18, 09:17 PM
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My observation is that it seems that all tubularsm no matter how wide they are, have the same width base tape - the part which is glued to the rim. My 22mm and 25 mm road tubulars and 28 and 32 mm cyclocross tubulars all fit on the same normal road width rim. I don't think you'll have any troubles.
08-20-18, 09:58 PM
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Not yet mentioned is how well the sew up's base contacts the rim's curve. On a wide rim with a "narrow" tire the rim can have a larger radius then the tire's. So the tire contacts the rim with a small amount of surface area centered on the tire's stitching (under the base tape). With a narrow rim and "wide" tire the tire contacts the rim along the sides of the stitching of the tire and on the sides of the rim. So what we end up is either a single contact/glued band or two bands. Large amounts of glue will help hold the single contact (wide rim/narrow tire) most of the time well enough. But why stand on one leg when you could use both legs (or the sides of the rim and tire)? And while you are trying to corner on that one leg let me toss a few pot holes (or tree roots if CX is your gig) in your path and we can talk again about the lack of more stable tire/rim matches.
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AndrewRStewart
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08-21-18, 09:57 AM
#6
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Old Tubular rims get a second use, in budget Cyclocross wheel-builds..
which typically use wider tires... and several wheels..
which typically use wider tires... and several wheels..
08-22-18, 04:20 AM
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All true, except the rim bed isn't usually a radius curve, it's more of a VEE shape, so narrow and wide tires all contact on the sides and not so much under the stitches.
08-22-18, 05:45 AM
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Although rim width doesn't vary much for tubular rims, the profile of the bed does. I have older rims, like Mavic 330's, that appear curved as opposed to V shaped and more modern Campagnolo rims that have a channel in the base of the profile allowing for the stitching. Being a C&V guy, I can't comment on newer rims, i.e. carbon.
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08-22-18, 05:53 AM
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I first experienced this way back in the 1970s. We still would still see 22mm (aprox) wide sew up rims but as at that era the trend to skinny 21-23mm sew ups was in full force we saw the poor fit and sometimes needed to build up the rim base with rim tape first. Fast forward to a few years ago and the cycling industry had come a full circle and wide rims became the sign of the fast rider, whether they fit the tires used best or not. Most often when one's CX wheels were used with road tires. Andy
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08-22-18, 01:41 PM
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I wish some of my customers used the rims you describe. The Major Toms and a couple of other wide rims (don't remember models now) didn't fit the road tires as you say. If the rims have double ferules for the spokes then these further lift the tire contact from the rim's surface. I'm a strong believer of matching tire and rim intended widths, be they sew up or wired on. Wide sew up rims only make sense to me if used with wide tires too.
I first experienced this way back in the 1970s. We still would still see 22mm (aprox) wide sew up rims but as at that era the trend to skinny 21-23mm sew ups was in full force we saw the poor fit and sometimes needed to build up the rim base with rim tape first. Fast forward to a few years ago and the cycling industry had come a full circle and wide rims became the sign of the fast rider, whether they fit the tires used best or not. Most often when one's CX wheels were used with road tires. Andy
I first experienced this way back in the 1970s. We still would still see 22mm (aprox) wide sew up rims but as at that era the trend to skinny 21-23mm sew ups was in full force we saw the poor fit and sometimes needed to build up the rim base with rim tape first. Fast forward to a few years ago and the cycling industry had come a full circle and wide rims became the sign of the fast rider, whether they fit the tires used best or not. Most often when one's CX wheels were used with road tires. Andy
This is a HED Belgium C2 I built up in January. It's listed as 23mm rim width, and the specs recommend 20mm or larger tires; I have 27mm tires mounted. I was kind of surprised at the bed profile but it makes a lot of sense when I researched why.
Major Tom rims are also listed as 23mm wide, and suggested tire size is 25-35mm... but they're intended for cyclocross so I wouldn't expect many folks would mount narrow tires anyway.
08-26-18, 03:59 PM
#11
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This is a HED Belgium C2 I built up in January. It's listed as 23mm rim width, and the specs recommend 20mm or larger tires; I have 27mm tires mounted. I was kind of surprised at the bed profile but it makes a lot of sense when I researched why.
Major Tom rims are also listed as 23mm wide, and suggested tire size is 25-35mm... but they're intended for cyclocross so I wouldn't expect many folks would mount narrow tires anyway.
Major Tom rims are also listed as 23mm wide, and suggested tire size is 25-35mm... but they're intended for cyclocross so I wouldn't expect many folks would mount narrow tires anyway.
