Angled brake track or straight brake track for maximum aero

[Marin]

Hambini, thanks for the explanation and good to see you back - always interesting info from you.

But *please* try not to call people "morons" etc. on here, it annoys me and many others, it's unnecessary and it will shorten your stay

Best,
Marin

[hambini]

Hambini, thanks for the explanation and good to see you back - always interesting info from you.

But *please* try not to call people "morons" etc. on here, it annoys me and many others, it's unnecessary and it will shorten your stay

Best,
Marin

If it annoys you, then please put me on block. All of the reasoning will be coming out in the next few days.

[AJS914]

Hambini, what does the drawing illustrate about angled brake tracks?

[mpulsiv]

I have drawn a really crap sketch on my marker board to illustrate what I think most people think airflow looks like and how it actually looks.
aerosketch.jpg
If you assume the conentious issue of yaw angle is the constant and zero, the top drawing shows how marketing perople show the aerofoils off. Nice steady flow going over the aerofoil section.

In reality the airflow is much more like the bottom sketch. The yaw angle is still zero but you get vortices and a solid body (the aerofoil) slicing through the turbulence, the air does not hit the aerofoil square on despite a zero yaw angle. This is the difference between effective and actual yaw angle.

For a wheel test to be valid and use steady state analysis like the top picture then you would need to increase the yaw angle to more than you think to give an accurate reading. My critics who are mainly on slowtwitch can argue over whether the systems I use for developing wind tunnel simulations to model the real world are accurate or not but they cannot argue the airflow hitting the wheel and tyre looks like the bottom picture (unless they are in still air in the middle of nowhere on a perfectly smooth surface with all bodies around at uniform temperature). When the airspeed gets faster (rider goes faster), the vortices and turblence is straightened by a stagnation point in front of the rider so the yaw angle gets smaller.

In general providing the sweep of the aerofoil is not too abrupt and the brake track is not designed poorly, a wheel with a DEEPER rim will always be faster. A deeper rim reduces the area of the wheel that has no solid boundary in it and reduces the drag from spokes. Hence a deeper rim will be faster.

The caveat is provided a moron hasn't designed it.

Hambini

Fair enough. Help me understand this layman terms. What is the consensus on narrower brake track? Based on my understanding, turbulence is increased at a lower speed.
Is there a valid reason to design a rim with an angled brake track? If so, I'd like to hear valid statements.

[hambini]

Hambini, what does the drawing illustrate about angled brake tracks?

In a wind tunnel with perfect flow, it may improve drag -depends on the rest of it.

Out on the road. Unlikely that the brake track by itself will make much difference.

It needs to be considered more of a system than an individual feature

[Marin]

Hambini, thanks for the explanation and good to see you back - always interesting info from you.

But *please* try not to call people "morons" etc. on here, it annoys me and many others, it's unnecessary and it will shorten your stay

Best,
Marin

If it annoys you, then please put me on block. All of the reasoning will be coming out in the next few days.

I don't want to put you on block, I really enjoy the engineering side!

Unfortunately, I didn't get my point across:

Even if "all the reasoning comes out" you shouldn't call people names.

It's *much* more effective if you just present the facts, and then let people make up their minds. If your readers then think "ok, they really are total morons" you won without being an ass

[youngs_modulus]

I don't want to put you on block, I really enjoy the engineering side!

Unfortunately, I didn't get my point across:

Even if "all the reasoning comes out" you shouldn't call people names.

It's *much* more effective if you just present the facts, and then let people make up their minds. If your readers then think "ok, they really are total morons" you won without being an ass

I second this. I'm a bit of a hypocrite because I don't suffer fools gladly, but frankly: I'd be more persuasive if I did. Also, who can argue with a call to civility?

Hambini, please consider that Marin has been really solicitous, even after your snarky retort. He has a point. I've only recently re-engaged with WW, but I think you might have a lot to contribute. Please don't ruin it with venom.

[hambini]

I think it's a fair point, so I must apologize to marin. Please consider this as that.

[Marin]

I think it's a fair point, so I must apologize to marin. Please consider this as that.