Hey Guys,
I switched my 700x20 tires for 700x23 … and now I have to adjust the screws to create a space between the frame cutout and the tire …
My question is , how far from the cutout should I put the wheel ? ( It’s a 2005 Blade )
Thanks
The simple solution is measure what you have now, and just repeat.
Far enough that you can slip a credit card all the way around. You don’t want a pebble or anything getting jammed in there, but a credit card at the highest point is usually okay. I believe that is the UCI minimum for the P3, but I don’t think the rear wheel cutout on the Blade has the internal curvature of the P3 cutout (i.e. the P3 cutout wraps around the wheel looking at the bike sideways, and also around the tire looking from the back), so you might want to go like two credit cards for your Blade.
Herbet is at Eurobike, but I am sure Litespeed tech support answers email.
This always make for a good chuckle
Think about the air your cutout hits … , your front brake and cable, fork, headtube, legs, water bottle (if used) all hit this still air first
The air is so turbulent when it hits your seattube, in my eyes, it seems that it matters little, if at all, if you have 3 or 15 cm of spacing
Are you jealous that you can’t adjust the spacing relative to the cutout on your Arcole? 
Well, 15cm might make SOME difference, if only because then the wheel would be out of the dropouts.
-C
My problem is that the old tires were 700x20 so the wheel was all the way forward and let me 4 mm from the cutout… now when I changed for michelins 700x23 I had to adjust.
Good tip from the credit card thanks !!!
I was afraid that if for some reason ( bumps for example, torsion ) the tire gets contact with the frame…
Thanks !!!
Luiz
Hey Gary,
Yes the flow is turbulent after it has crossed the first part of your body, but there is always the possibility of “re-attaching” some part of the flow and reducing the size of the low pressure zone aft of the rider.
There are many studies in aeronautics and fluid mechanics dedicated to the theory of flow re-attachment. Look at wing fences and vortex generators on aircraft, all designed to re-energize the flow.
Now how much the cutout of the P3 helps in terms of aerodynamics over a triathlon course, I wouldn’t like to speculate. I would suggest that the ability to stay in the aero position longer has a much greater effect. However, the turbulence created by the rotating leading edge of a wheel does have a big effect… one that is reduced by creating a laminar flow over the seat tube that is not as disrupted by the leading edge of the tire. In order to get this effect, you have to get the tire as close to the seat tube as possible.
Gains in minutes? Maybe not… but when you can miss a world championship win or a Kona slot by seconds, I’d say there was an advantage worth taking.
oops, I meant MM
The Arcole has 8 or 9 mm of clearance, so the difference is maybe 6mm of spacing between the Arcole and the P3
I guess I will never win the world championships unless I get that P3
my new Barolo has the same spacing, 8mm
Not jealous, the P3 is OK, but Javelins are much cooler in my opinion - hot rods
its the motor that makes the difference
- gary
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Motor makes the difference… I hear ya…
I’m not a P3 owner and probably never will be… I figure I have to lose some weight, gain some speed and train a lot harder before it’s worth it. I was just trying to say that there is some aerodynamic effect to the cutout… but I promise I’ll get off my soapbox…
And the javelin… definitely a hot rod… I’ll just sit here drooling and dreaming shall I?
If I wanted to get a P3C, I would get one tomorrow
Nice frame, not my kind of geometry
Carbon is nice, and the Barolo has a carbon rear, but I like the “bulletproof” feeling the Arcole gives
It is a bad ass frame, wicked fast and built like a jet fighter
.
Hello,
Thats an off repeated myth (that because the air is dirty aero doesn’t matter). Think about it this way in dirty air the tube still has to push aside air molecules, they are just moving in random directions, but they still must be moved and that takes energy. An aero tube will have to move less molecules a shorter distance. It is true that “still air” takes more energy to move, but its certainly not enough less that it nullifies aero properties. Now of course we can argue the magnitude of benefit from aerotubing in the first place.
Styrrell
I dont think the issue is aero tubing, but space between the cutout
Does 6mm closer to the seattube make the P3 faster than the Arcole?
Who knows, probably makes no difference really.
Hello, How close is a question which probably can’t be answered without a windtunnel and a powermeter setup. I remember when the first frames with cutouts came out. At the time the prevailing wisdo was that too close was bad because the wheel would try to pull air inthe space and without room to exit friction would result. Now everyone seems to believe that closer is better.
Styrrell
I doubt you could measure the cutout in a wind tunnel with a powermeter, highly doubtful there is even a detectable difference
When a rider punches a hole through the air, most of that air is moved around the rider, e.g. look at smoke and how it displaces and moves around the sides of the rider, now how much of that smoke actually hits the settube - and then how much does 6mm of a gap matter?
Like I said its a small difference in any. One thing you have to realise is that the smoke in a WT is indicative of how much air is being displaced and moved. When you see the smoke part and stay continuous thats good. When you see the smoke become disrupted, thats bad. In both cases every part of the bike still is cutting through air, just because the smoke is parted before the seat tube doesn’t mean that the seatube isn’t cutting through air just as dense as the air that was being marked with the smoke. My guess is that from 0 - 10 mm you loose very little aero benefit. I’m still curious if moving to close, without any rubbing causes some power loses.
Styrrell
One reason I am not a fan of horizontal dropouts is the wheel change issue
Many people do not know this, but the Barolo has an option for horizontal dropouts - but why bother, only 6mm closer to the tube, which may or may not increase friction as is
Like shaving your arms, can it be measurably faster?
Like I said its a small difference in any. One thing you have to realise is that the smoke in a WT is indicative of how much air is being displaced and moved. When you see the smoke part and stay continuous thats good. When you see the smoke become disrupted, thats bad. In both cases every part of the bike still is cutting through air, just because the smoke is parted before the seat tube doesn’t mean that the seatube isn’t cutting through air just as dense as the air that was being marked with the smoke. My guess is that from 0 - 10 mm you loose very little aero benefit. I’m still curious if moving to close, without any rubbing causes some power loses.
Styrrell
How could that cause power losses if there’s no rubbing?
Personally, I put the wheel on my P3 a little further out than credit card distance. A lot of things flex under power. Even if a wheel doesn’t rub on the stand, it may still rub on the road when you’re weighting and powering it.
As far as the aerodynamics go, I think the only one around here who has actually tested it in a wind tunnel is Gerard. And I believe he claimed a while back that the wheel needs to be very close.
– Jens
Like I said its a small difference in any. One thing you have to realise is that the smoke in a WT is indicative of how much air is being displaced and moved. When you see the smoke part and stay continuous thats good. When you see the smoke become disrupted, thats bad. In both cases every part of the bike still is cutting through air, just because the smoke is parted before the seat tube doesn’t mean that the seatube isn’t cutting through air just as dense as the air that was being marked with the smoke. My guess is that from 0 - 10 mm you loose very little aero benefit. I’m still curious if moving to close, without any rubbing causes some power loses.
Styrrell
How could that cause power losses if there’s no rubbing? Reply: The theory is that with the wheel very close that the spinning tire will draw air into the gap and that air will have a hard time getting out, causing more friction. I have no idea if this is true or not. A wind tunnel will not show this because it isn’t connected to aerdynamics, just power loss. Also, and don’t take this as a specific criticism of Gerard or Cervelo, but mfg frequently tout benfits of their design when they don’t exist.
– Jens
Styrrell
Unless you are riding at speeds in excess of 25mph, you should not worry about it.
I know … And definately I’m not a 25mph guy… but I paid a good amount of money on the frame so I want to take all from it…even if it is 0.0001mph…