Finding a 150mm campy track crank was fine, but removing a set of brakes is a pain? Sorry mate, no pass.
You do need to get that cabling fixed. I think that enough people have done the top tube entry now that you could consider it safe. Especially with just one additional hole.
For my money (several times over), I would put a Ventus on there. If you need a -17 bar, I will sell you my last one because I know it’s for a good cause.
I do have an important question though. In determining the P3C faster, what speed were you testing at?
One of the of the other improvements I’m planning is to switch to a USE tula bar or aero-or-die. Neither of these would be possible with the P5 – unless I replaced the Magura brakes, which would be a big pain.
Maybe the aero gurus can explain how this works, because I don’t see how narrowing q-factor by 17mm changes frontal area of your legs at all. Maybe if you were pedaling like a bow-legged sailor before, but my thighs at “normal” q-factor spacing are pretty much parallel. If I put them 3 cm closer together, I still have just as much leg, it’s just placed closer to the frame. So does the aero improvement come not from a reduction in frontal area, but rather from a smoothing of the flow around the legs and/or fairing of the rear part of the bike from air flow? I’m also curious if you did this testing with a disc wheel. Just trying to figure out how this works.
Well I’m way more aero than Jens for one. Also, my track bike CdA is much higher than my TT bike CdA, and that’s with a narrower Q. Also, there’s just no way I’d be able ride with that low of Q and not break the chainstays.
How low is your track bike Q?
How can you compare your CdA to someone else’s, or indeed between your bikes.
I would have thought all the time you have spent with Xav you’d know it would make you more aero, whether you can do it or not is the point Jens is making.
He’s making the point that most modern superbikes aren’t all that adjustable when it comes to things like Q, which as he has shown for him makes him more aero.
Might not work for everyone, but it worked for me!
Maybe the aero gurus can explain how this works, because I don’t see how narrowing q-factor by 17mm changes frontal area of your legs at all. Maybe if you were pedaling like a bow-legged sailor before, but my thighs at “normal” q-factor spacing are pretty much parallel. If I put them 3 cm closer together, I still have just as much leg, it’s just placed closer to the frame. So does the aero improvement come not from a reduction in frontal area, but rather from a smoothing of the flow around the legs and/or fairing of the rear part of the bike from air flow? I’m also curious if you did this testing with a disc wheel. Just trying to figure out how this works.
I’m not a guru by any means, but I can offer a few points. I got a wind-tunnel documented improvement of ~7 watts going from a q factor of 149 to 132 (17 mm reduction). I think this may have under-estimated the improvement, because it was the last run of the day and I was getting tired and sloppy. In field testing I gained roughly that much again by narrowing another 12 mm.
I think I misled by discussing frontal area. You are absolutely right that your legs’ frontal area is what it is, whether they are 120 mm or 2 feet apart. It’s really about how the air flow re-attaches. If your legs are way out there by themselves in the wind, the flow isn’t going to re-attach as well. How close your legs have to be for flow to re-attach is probably a factor of the size our your legs, the frame, wheels, and a whole bunch of factors. From my experience, I’m guessing there’s an inflection point somewhere between 150 and 130, where there is a dramatic improvement. Previously, I did some testing between 165 and 150 and saw very little difference ( As long as your legs are way out there, it doesn’t matter if its 155 or 200).
Incidentally, I am puzzled that many people here believe that socks with a strip on them will gain them 5 watts, but think that bringing their legs 3cm closer together does nothing.
It’s 136mm on my track bike. Seems pretty easy to compare when they all have known CdAs…
You seem to be missing the point. A Q factor narrow enough to drop my CdA is only achievable on older frames, but those frames are all slower than the P5 (among others). So it’s not as if it hasn’t been considered, it just makes no sense (especially if you have a P5). And again, with that narrower a Q factor, my heels would just bounce off the chainstays.
