Tubular or clinchers road wheel

['Dale]

Also the classifieds have alot more carbon tubbies than clinchers as well and cheaper but yes I know tubbies are more expensive but do you really go through a pair that often?

 

Only serious cuts can damage a tubby

And the rubber compound is thicker than a clincher

Tubbies can last long

 

I had to replace mine recently due to a sidewalk cut while clipping a cat eye

[Johan Bornman]

From Mavic

 

This alloy core is wrapped with a 40mm carbon fibre rim. The brake track is then finished with Mavic's proprietary heat treatment process, involving two types of resin in the braking surface. It calls this TgMAX technology, and claims the Tg point (glass transition temperature is the point at which the resin gets hot enough to revert to its liquid state) is able to exceed 280°C. They tested this with a 100kg rider on a 10km downhill

 

These are just numbers they throw out to fill space on the website and to give a scientific flair to their high-tech mumble-jumble.

 

Firstly, they don't say how often the rider applied brakes. He may only have braked once and a peak temperature of X appeared on the apparatus. The number is useless. What is important is how a wheel handles the heat generated at the brake/rim interface.

 

Heat is generated in the softest of the two friction materials, in this case, the rubber brake block. Heat is generated in the block at the actual surface touching the rim, through stretching and breaking the bonds between the rubber molecules.

 

Since rubber is a reasonably good insulator, the heat cannot move backwards through the rubber into the metal brake shoe. It gets transferred to the rim via conduction. If it is an aluminium rim, the rim readily accepts the heat and disperses of it via radiation and contact with air. It is a large heat sink with ample cooling and only heavy overload of the system will cause the input heat to exceed the wheel's capacity to get rid of it.

 

With the same scenario in carbon: the pad generates heat but it cannot go anywhere - not backwards, not forwards, since carbon is a poor conductor and doesn't accept the heat as readily as aluminium does. The result is melting pads and sticky rubber smear on the rims. The solution to this problem is pads that don't melt but sublimate - like wood or cork. It doesn't turn liquid but smokes. This solves the problem of melting pads that cause sudden loss of braking force. But, it doesn't solve the problem of poor braking performance in the first place, and all the subsequent issues of accelerated brake track wear, delamination etc etc.

 

Some wheel manufacturers play around with alu tracks and alu cores, but the informed buyer will be able to distinguish between real heat dissipation and compromised heat dissipation based on the facts above.

 

A simple temperature reading tells us nothing.

[urbanroyal]

And how are you doing Mr Borman...its been some time since you posted ....quiet day in the Scottish meadows I take it ....or is it Ireland....

[Johan Bornman]

Only serious cuts can damage a tubby

And the rubber compound is thicker than a clincher

Tubbies can last long

 

I had to replace mine recently due to a sidewalk cut while clipping a cat eye

 

No.

 

Tubbes and clinchers can be made from the same fibres and rubber. The exact materials are chosen for characteristics other than whether the tyre will be a clincher or a tubular.

 

Tubbies are not made thicker, that would defeat the object of attempting to lower the rolling resistance. If anything, they will be thinner.

 

Therefore, the only way to make them stronger from a cut and puncture perspective is to make them thicker and thicker is bad, in the context of this discussion - performance.

 

Further, "rubber compound" refers to the type of rubber. The compound has nothing to do with the thickness. They make it as thick/thin as they want, irrespective of the compound.

 

Lets not forget that silly gormless ass, Ale Erwin, with his "bolt substance" that was supposedly chucked into Koeberg's turbine by saboteurs.

[Johan Bornman]

And how are you doing Mr Borman...its been some time since you posted ....quiet day in the Scottish meadows I take it ....or is it Ireland....

West coast of Scotland. Beautiful day here. Think I'll go and find meself a nice moore somewhere and go for a wee walk.

[urbanroyal]

Lekka man enjoy ....and please don't be a stranger ....your advice ...always welcome ...

['Dale]

No.

 

Tubbes and clinchers can be made from the same fibres and rubber. The exact materials are chosen for characteristics other than whether the tyre will be a clincher or a tubular.

 

Tubbies are not made thicker, that would defeat the object of attempting to lower the rolling resistance. If anything, they will be thinner.

 

Therefore, the only way to make them stronger from a cut and puncture perspective is to make them thicker and thicker is bad, in the context of this discussion - performance.

 

Further, "rubber compound" refers to the type of rubber. The compound has nothing to do with the thickness. They make it as thick/thin as they want, irrespective of the compound.

 

Lets not forget that silly gormless ass, Ale Erwin, with his "bolt substance" that was supposedly chucked into Koeberg's turbine by saboteurs.

 

Thanx for an expert point of view, JB.

Makes good sense.

Le'me adjust my perspective and head down to EvoBikes for that recent discount on tubbies (since they're not tougher... )

Edited June 15, 2014 by ' Dale

[gummibear]

These are just numbers they throw out to fill space on the website and to give a scientific flair to their high-tech mumble-jumble.

 

Firstly, they don't say how often the rider applied brakes. He may only have braked once and a peak temperature of X appeared on the apparatus. The number is useless. What is important is how a wheel handles the heat generated at the brake/rim interface.

 

Heat is generated in the softest of the two friction materials, in this case, the rubber brake block. Heat is generated in the block at the actual surface touching the rim, through stretching and breaking the bonds between the rubber molecules.

 

Since rubber is a reasonably good insulator, the heat cannot move backwards through the rubber into the metal brake shoe. It gets transferred to the rim via conduction. If it is an aluminium rim, the rim readily accepts the heat and disperses of it via radiation and contact with air. It is a large heat sink with ample cooling and only heavy overload of the system will cause the input heat to exceed the wheel's capacity to get rid of it.

 

With the same scenario in carbon: the pad generates heat but it cannot go anywhere - not backwards, not forwards, since carbon is a poor conductor and doesn't accept the heat as readily as aluminium does. The result is melting pads and sticky rubber smear on the rims. The solution to this problem is pads that don't melt but sublimate - like wood or cork. It doesn't turn liquid but smokes. This solves the problem of melting pads that cause sudden loss of braking force. But, it doesn't solve the problem of poor braking performance in the first place, and all the subsequent issues of accelerated brake track wear, delamination etc etc.

 

Some wheel manufacturers play around with alu tracks and alu cores, but the informed buyer will be able to distinguish between real heat dissipation and compromised heat dissipation based on the facts above.

 

A simple temperature reading tells us nothing.

 

I've had brake pads melt with alu rims but haven't had a issue with my carbon wheels......except braking in the rain.

 

Pretty scary when you can smell the rubber melting and you not slowing down much.

[Johan Bornman]

I've had brake pads melt with alu rims but haven't had a issue with my carbon wheels......except braking in the rain.

 

Pretty scary when you can smell the rubber melting and you not slowing down much.

 

That is pretty scary. I've had it happen to me only in one place, in the Suikerbosrand nature reserve, down the mineshaft. My experience was slightly different from yours. I didn't smell anything (only in my shorts afterwards) but felt a sensation on my thighs like going through a swarm of muggies. Afterwards when I could look and think, it turned out to be rubber sawdust. It seems to me that the rubber melts, gets thrown out by the revolving rim, solidifies in the air and then settles on your (hairy) thighs. It took me a while to figure out what the sawdust was.

The sensation was unpleasant. One second you have brakes and the next, nothing. Common sense overcame my instinct and I released the brakes for a second or two. This helped the rim cool down enough to be below the rubber melting point again and I suddenly had brakes again.

 

More recently, I rode down Huisrevierspas near Ladysmit (?) in the Karoo with a fully loaded rim brake bike and fully expected the same to happen. This time however I alternated between front and back brake and used it differently. I would brake hard for a short section, release, swap sides and brake hard again. This seemed to have done the trick. However, the only way to test that theory is to go back to Suikerbosrand to Knyp-'n-Washer hill and do it with the modified technique. I'lll leave it to someone else to do and report back.

[Johan Bornman]

I've had brake pads melt with alu rims but haven't had a issue with my carbon wheels......except braking in the rain.

cut cut cut cut

 

You won't notice impaired braking performance with carbon wheels except like you observed, in the rain. However, down a long steep hill, poor performance is very noticeable. They just don't stop as quick as alu rims. It's like cars with drum brakes versus disc brakes. The difference is only noticeable if you really push it. Aunt Mabel in her 1100 Yaris doesn't know the difference.

 

The average ZA race just doesn't test the rims to their limits.

[GoLefty!!]

You won't notice impaired braking performance with carbon wheels except like you observed, in the rain. However, down a long steep hill, poor performance is very noticeable. They just don't stop as quick as alu rims. It's like cars with drum brakes versus disc brakes. The difference is only noticeable if you really push it. Aunt Mabel in her 1100 Yaris doesn't know the difference.

 

The average ZA race just doesn't test the rims to their limits.

 

Carbon rims require carbon carbon brake pads. Pretty expensive those are and I don't know of any company that makes something like that. Thats whats helps an Fq car stop. High brake system pressure and carbon carbon pads on carbon disc pads. Wear rate is massive and of course they have very special cooling shrouds,

 

for me, carbon wheels are for race day when you have other soft bodies to fall on top of. For training, I'll stick to aluminium

[SwissVan]

for me, carbon wheels are for race day when you have other soft bodies to fall on top of. For training, I'll stick to aluminium

 

 

The only problem is then u need to change your brake pads when you change wheels, pads used with alu rims have all those nasty little bits embedded in them which could damage your expensive carbon rim braking surface....

 

Not a major issue to change if u have time to spare AND depending on where your brake caliper is located of course!!

 

Spot the caliper

 

 

['Dale]

Swisstop's Blackprince brake pads are reasonably good with my alu and carbon wiele

 

Durability much better after the Yellow

[SwissVan]

 

Swisstop's Blackprince brake pads are reasonably good with my alu and carbon wiele

 

 

 

Do u use the same set of pads for both wheel sets?

['Dale]

 

 

Do u use the same set of pads for both wheel sets?

 

Yebo

[SwissVan]

Yebo

 

Is that a carbon wheel with carbon brake surface?

 

Take care, from Zipps support page