Can anyone point me to testing / documentation quantifying that wider rim with lower pressure is faster? Ref. front pace article about the new Zipp disc.
I’m lookkng to buy a disc wheel and I have options ranging from 19 to 23 mm inner width with optimal tire diameter and pressures rangling from 25mm @ 85psi to 30mm @ 60 psi. Assuming aerodynamics are the same, what is the power difference between 25mm @ 85psi and 30mm @ 60psi with say a GP 5000 TT at 45 kph?
Information I can find on tyre pressure is conflicting……
There’s no good data showing that if you keep casing tension constant between wider/narrower rim/tires that wider rims/tires are actually faster. Barring super bad roads.
If anything wider rim means you need to use a wider tire. Which then causes more drag, even in the rear (just reduced).
wider tire, lower pressure, less contact resistance? so faster…
of course, the tire needs to be a good fit onto the wide rim…so a wide tire smashed on a tiny rim, will always be bad for airflow?
that is what i have heard?
If anything wider rim means you need to use a wider tire. Which then causes more drag, even in the rear (just reduced).
I think it is the other way around. Wider tire means one should mount it on a wider rim for acceptable aerodynamics. In addition, with wider tire the rim should become deeper in order to realize a reasonable aspect ratio. Which in turn however, increases the cross wind sensitivity.
On wide hooked clincher rims one can (safely) mount relatively narrow tires. At least in our velodrome tests such setups often turned out fastest.
wider tire, lower pressure, less contact resistance? so faster…
of course, the tire needs to be a good fit onto the wide rim…so a wide tire smashed on a tiny rim, will always be bad for airflow?
that is what i have heard?
Think this is wrong.
The contact area only reduces if tire pressure stays the same when going to wider tire.
But most peaple run lower pressure with wider tires. So the contact aera will be similar.
wider tire, lower pressure, less contact resistance? so faster…
of course, the tire needs to be a good fit onto the wide rim…so a wide tire smashed on a tiny rim, will always be bad for airflow?
that is what i have heard?
Think this is wrong.
The contact area only reduces if tire pressure stays the same when going to wider tire.
But most peaple run lower pressure with wider tires. So the contact aera will be similar.
you are correct, the contact area increases but resistance only drops if pressure stays the same…
If anything wider rim means you need to use a wider tire. Which then causes more drag, even in the rear (just reduced).
I think it is the other way around. Wider tire means one should mount it on a wider rim for acceptable aerodynamics. In addition, with wider tire the rim should become deeper in order to realize a reasonable aspect ratio. Which in turn however, increases the cross wind sensitivity.
On wide hooked clincher rims one can (safely) mount relatively narrow tires. At least in our velodrome tests such setups often turned out fastest.
The 23mm wide internal width wheel he’s looking at means that he is forced to run wider tires. You can’t fit a 23mm tire on there safely and maybe not even a 25mm. So he has to run a 28mm which is less aero. Here the wheel manufactures are forcing users to run wider tires. Especially as many wheels are hookless meaning heavier riders say 180 lbs can’t run a 23mm as it would require pressures above the safe ~75 psi limit.
The 23mm wide internal width wheel he’s looking at means that he is forced to run wider tires. You can’t fit a 23mm tire on there safely and maybe not even a 25mm. So he has to run a 28mm which is less aero. Here the wheel manufactures are forcing users to run wider tires. Especially as many wheels are hookless meaning heavier riders say 180 lbs can’t run a 23mm as it would require pressures above the safe ~75 psi limit.
I.e. do not buy a hookless rim for fast riding on roads, one is in many ways too much restricted.
I.e. do not buy a hookless rim for fast riding on roads, one is in many ways too much restricted.
4 front page articles, endless threads …summarized in one sentence
Dan is awesome and super smart, and as the founder he should have an outsized influence on the discussion, but he’s almost the only one promoting hookless as a good product for road cycling.
I.e. do not buy a hookless rim for fast riding on roads, one is in many ways too much restricted.
4 front page articles, endless threads …summarized in one sentence
Dan is awesome and super smart, and as the founder he should have an outsized influence on the discussion, but he’s almost the only one promoting hookless as a good product for road cycling.
the balance between showcasing for your sponsors, showing the future potential/trends and giving the tangible pros and cons for the consumer, the ones reading your review and considering a purchase today, is a delicate balance.
Maybe in the absence of data, there should be more emphasis on YMMV
And another from one of the home page articles with Dan & Josh:
This was a manufacturing advance that allowed companies to make carbon wheels both cheaper and more quickly than they can make hook bead style rims, and as a result, almost all of the ‘benefits’ attached to hookless thus far have been the creations of marketing departments…
I am yet to see a single feature/benefit pair from anybody’s marketing department actually play out in lab or wind tunnel testing, and I’m also not really noticing prices come down either.
This is consistent with so many other experts that test stuff. Because of the limitations, hookless systems are not fast. They might be as fast on bad road surfaces as hooked, but no faster. And hooked would be faster on better road surfaces. Further, hookless seems to introduce a significant blowout risk from user error.
Unlike other advances, it does not seem like hookless will get faster or safer with more R&D & refinement; it seems to be an inherently flawed design.
Another recent “advance” in road cycling that’s a function of marketing departments is continuously wider wheels to make people want to buy new equipment. They are great for gravel but not any faster or more comfortable for road, if you’re running the right pressures.
Another recent “advance” in road cycling that’s a function of marketing departments is continuously wider wheels to make people want to buy new equipment. They are great for gravel but not any faster or more comfortable for road, if you’re running the right pressures.I do not believe this is accurate, based on rolling resistance and all the tests that experts in the other threads posted. And as another said, the comfort difference is not subtle.
As said above if you don’t make pressure adjustments (lower the correct amount) for wider tires, then yes wider will be faster and more comfortable. But there hasn’t been any data showing that when you do, wider tires are faster on decent surfaces. If you know of any please share it with me.
The same applies to comfort, and that’s harder to measure especially with how powerful the placebo effect is.