clinchers vs tubs

[mcshroom]

Is there a reason why they use tubular tyres for racing? I've never used any so I don't now of any differences.

Or do they still use tubs?

[LittleWheelsandBig]

Tub rims are lighter and they are safer to ride to a stop when punctured.

[mark]

1. The flanges on a clincher rim will cut the tire & tube easily when the wheel hits a pothole or other obstacle, causing a pinch flat. To compensate, clincher tires are typically inflated to a higher pressure for a given tire size & rider weight, resulting in a harsher ride, higher rolling resistance and more rider fatigue.

2. When a clincher tire is inflated, the air pressure spreads the flanges apart horizontally. Unless the rim has hook beads and an extra layer of metal in the horizontal part of the "U" (like this: [_] ), the tire cannot be inflated to a high enough pressure to avoid pinch flats without blowing the tire off the rim. When a tubular tire is inflated, the air pressure compresses the rim radially, strengthening it. So the tubular rim can be made lighter than the clincher rim without compromising the durability and reliability of the tire and wheel combination. Here are some rim cross-sections to show what I'm talking about: http://www.velocityusa.com/default.asp?contentID=563 . The "Escape" and the "Pro-Elite" are tubular rims, the others are clincher rims. Notice that the "Escape" is distinctly lighter than clincher rims of similar dimensions.

And yes, I'm told that tubulars are safer to ride flat and are less likely to be damaged while doing so than clinchers.

[mcshroom]

1. The flanges on a clincher rim will cut the tire & tube easily when the wheel hits a pothole or other obstacle, causing a pinch flat. To compensate, clincher tires are typically inflated to a higher pressure for a given tire size & rider weight, resulting in a harsher ride, higher rolling resistance and more rider fatigue.

Surely the higher the pressure, the lower the rolling resistance of a tyre as it deforms less?

[mark]

Surely the higher the pressure, the lower the rolling resistance of a tyre as it deforms less?

Depends on the road surface. On a very smooth surface higher tire pressure/ less deformity will result in reduced rolling resistance. As the road surface gets rougher, the higher pressure tire will be lifted up and over irregularities (as will the attached bicycle and rider), resulting in greater rolling resistance. If the surface gets rough enough, the bicycle with high pressure tires will start bouncing around, reducing control and limiting speed. It's pretty simple to boost the pressure in a tubular tire for extra smooth roads, but reducing pressure in a clincher for rough roads will raise the risk of pinch flats.

[Jakob]

Better ride quality. My theory is that since the tubular is round and in combination with the glue, it absorbs a lot of vibrations better than a clincher.
I started riding tubulars some 5-6 years after buying an old campagnolo wheel on ebay. Plan was to get rid of the tubular rim, but decided to try it out and I've never looked back. I can ride with 100PSI and it'll have the firmness of a 140PSI clincher, without the harshness...and when cornering hard, it feels like it grips the road better.

[giropaul]

1. The flanges on a clincher rim will cut the tire & tube easily when the wheel hits a pothole or other obstacle, causing a pinch flat. To compensate, clincher tires are typically inflated to a higher pressure for a given tire size & rider weight, resulting in a harsher ride, higher rolling resistance and more rider fatigue.

Surely the higher the pressure, the lower the rolling resistance of a tyre as it deforms less?

Would be true - if tubs were made of the same material as a pressure. However, with a tub the fabric can be "finer"; silk in the best tyres; and therefore they deform more, but weigh less.

[Exit Stage Left]

The question is more a case of why would pros ride clinchers? The rims for tubs are more flexible, so they contribute to suspension, as in this video. http://www.youtube.com/watch?feature=player_embedded&v=W1QXKjc1nLY The advantages of clinchers are that they are easy to mend, and are cheaper, neither of which matters at a high level. The principal advantage of clinchers is for use under sustained braking, where glue might melt on tubs. Indurain rode with a front clincher on mountain stages for that reason.

[Ian H]

...Unless the rim has hook beads...

Are there still rims made that don't have hook beads?

[GraemeMcC]

Tub rims are lighter and they are safer to ride to a stop when punctured.

The tyres themselves can also be a lot lighter. For time trialling on "fast" courses, my Tufo tubs are 165g each. And they can go to over 200psi if you can take the harshness.
I ride these on my HED tri/disk set on dual carriageway courses such as L1015, J5/8 or on the A1 in Notts/Yorks.

But anywhere else or whenever its windy, its the lightweight clinchers - Veloflex Masters - on aero rims, at 125psi max, or Michelins at 100psi on rough Cheshire J2&J4 series courses...

[Biggsy]

The very lightest silk tubs aren't always used for ordinary road stages due to their vulnerability to punctures.  Nowadays there are clincher versions of practical racing tubs using all the same materials for the casing and tread, such as the Vittoria Open Corsa, so the differences are narrowing. 

[mark]

...Unless the rim has hook beads...

Are there still rims made that don't have hook beads?

Cheap ones used on BSOs.

[Ewan Houzami]

The question is more a case of why would pros ride clinchers? The rims for tubs are more flexible, so they contribute to suspension, as in this video. The advantages of clinchers are that they are easy to mend, and are cheaper, neither of which matters at a high level. The principal advantage of clinchers is for use under sustained braking, where glue might melt on tubs. Indurain rode with a front clincher on mountain stages for that reason.

Clinchers used this year

http://velonews.competitor.com/2012/07/news/tour-tech-climbing-wheels-for-the-queen-stage-of-the-2012-tour-de-france_229316/attachment/american-classic-mag300 *

At least I assume they're clinchers as American Classic don't appear to make Mag300s in sprint form.

And didn't somebody take the TT World Championship a couple of years ago on some ? Ride quality aside, rolling resistance has been shown to be lower than sprints / tubs for certain high pressure (clincher) tyres when used with a thin 'n' stretchy latex tube. I think Open Corsas usually come out top in this regard.

*On a good day, I can remember how to use hyperlinks.