Aerodynamics / Aerodynamic Cost / Aero parts

Shorter cranks = reduced frontal area I guess. But surely the difference is seriously marginal.

But surely the difference is seriously marginal

If @dan can do as well as the best rider in the Cervelo test, he could score 0.007m² off his C_dA by swapping from 172.5mm to 165mm. Not sure what your definition of "seriously marginal" is, but over 2% drag reduction (assuming he's already at <0.35m²) is not to be sniffed at.

Of course, he might be like Rider 1 and increase his drag by just as much, which is why nobody can give him a definitive answer without testing.

0.007m^2? So just so I can picture that, thats an 8.3cm x 8.3cm square reduction. I don't understand how that's possible with a 7.5mm reduction in crank length. Am I missing something?

CdA isn't just about A.

#magnets

Am I missing something?

You're probably missing the fact that they raised the saddles to keep leg extension the same for all crank lengths, but didn't touch the bars. That effectively increased the saddle to bar drop, which would have changed the torso angle.

Playing the devil's advocate though, don't longer cranks allow for bigger ratios, less spinning, more aero efficiency?

This is track, its all about leg speed. Smaller circles makes higher rpm easier.

Am I right in thinking that having shorter cranks will allow for a better hip angle in a relatively aero position @mdcc_tester ?
Also what kind of time gain would a 2% reduction give over 200m @60-62 km/h ?

I believe Wiggins was on 170s

http://www.bikeradar.com/road/gear/category/bikes/road/product/review-specialized-s-works-venge-vias-49566/

You bought one yet?

Ok, well if we're going to include optimisations to rider position on top of swapping the cranks then I can believe that.

This was my point. Shorter cranks might facilitate a more aero position, but simply changing cranks length and keeping your old position won't change much.

But you should be changing your saddle height to allow for the different crank length. That's going to change your position in some way.

if we're going to include optimisations to rider position

In the Cervelo tests, it wasn't an optimisation, it was just picking one fit dimension to leave unchanged. I think in some cases they were then able to make use of the hip angle opening from short cranks to lower the front end and get even better aeros.

This is track, its all about leg speed. Smaller circles makes higher rpm easier.

And longer cranks make pushing a big gear easier. Why do so many apparently sane people still have so much trouble with the idea that crank length is largely irrelevant to power production as long as you keep gain ratio constant? If you read the Cervelo paper, you'll see that they noted the effect yet again, with riders dropping crank length by 5% self selecting 5% lower gears and 5% higher cadence :-)

simply changing cranks length and keeping your old position

Keeping which position? Saddle position relative to the pedals can be set is several possible ways, so "keeping" your KOPS would mean moving the saddle back if you selected shorter crank, for example.

That's pursuit riding - he was on 111" or something bananas. He's also 8cm taller than me with a silly inseam.

In any kind of racing that involves changes of pace (I.e bunch racing) you're better off with a smaller gear and higher revs as it will cause less fatigue.

So, even if spinning faster, shorter cranks can be more aero efficient than a longer crank al lower rpm?
It's really marginal but if hypothetically taken in isolation and brought to extremes, a metre long crankset spinning very slowly is in fact probably less aerodynamic than a 10 cm one spinning very fast with a lower gear ratio but producing the same speed. Or am I wrong?

taken in isolation

You can't (or at least shouldn't) take it in isolation.

I'll be wearing either a Bambino or C-Originals G14 for masters nationals points race this Sunday. They're the same speed on me.

How do you rate the G14 in terms of quality etc.

I'm considering selling my Giro Air attack and picking one up. I'd probably road race With all but the side panels installed, race tris With them in Place, and Train With it stripped Down.

I very much like my air attack. But the addition of side panels seems like a neat idea. Especially the size of my ears!

Just had a look at those g14's - pretty cool. Wouldn't train in one, but would be great for racing in a bunch of different conditions. Like the option of being able to have the ears open in a bunch race and closed in a mathch sprint/kilo/200.
They're also not insanely expensive.

370g

So not for climbing maybe. But I have another helmet for that.

I like the visor for group stuff. Feel i can see more. Thats a bit phycological though.

Has anyone used that Sugru stuff to sculpt non-aero shit into more aero shit? I apologise for my use of advanced terminology.

Basically, I swapped my bars to TriRig but couldn't use their stem because it's too long (so much for one-size-fits-all). I have a cheapie stock stem on and wondered about filling in the gaps a bit. It's probably likely to have the opposite effect isn't it as I create even more frontal area? Stupid bikes. After this season, I'm definitely swapping racing for Warcraft or some shit.