Rear wheel aerodynamics? Campy Atlanta vs FiR EA10
 

I'm considering to build myself a good rear wheel for the kilo TT around a Campagnolo Atlanta, 32 spokes (thinking about DT aerolite), and would like to know what the weight differences and/or aero-ness would be like. My current training wheel is built with FiR EA10 rim, 36 spokes (DT Comp).

The Atlanta is surely pretty bulky, but if the difference is within like 200g, I reckon off-the-line quickness wouldn't be hindered that much, and the aerodinamics would give me some sort of advantage twards the end?

(Kilo time: 1'15, standing lap split time 26sec.)

Any thoughts? Also, do anyone get the weight of the EA10. Seems hard to find data about them old stuff these days. Or maybe those old-timers didn't really care about the weighty-winnie thing.

Got somethin' against disc wheels? I like spokes too, but surely for a TT rear wheel a disc is the way to go, no?

How about this one: budget

:saweeet:

Surely I'm trying on borrowing around... this is kind of a backup option.

Build what you want. But if budget is keeping you from a disc, I'd use the money to pay for gym fees and protein shakes instead of the wheel. Lots of people have ridden 1:10 on regular old school spoke wheels.

I agree in that the aero benefits will be negligible between those rims.

I don't remember the EA10 off hand, but I built a lot of FiR rims back in the day. I mean, yeah, I've seen them, but I can't remember being impressed with it in a good or bad way.

I'd save my pennies and get some taller wheel, especially in the front. The front wheel will make the most difference aerodynamically (and coincidentally they're cheaper too).

I ride a TriSpoke/HED3 front wheel and a 32H M17 rear on the track, at least for now.

cdr

I use Corima Aero road wheels (borrowed) w/ allen screwers on the front, so that's no problem...

I don't know if you have any contacts that have been around for a while?

You may be able to get a 24H old Zipp rim (340 or 440). They can be built 16/8 x2/radial on a 32H hub. I've seen them for as little as $100 street price. In fact, I'm trying to get my hands on a pair from an old teammate who doesn't want tubulars anymore, specifically to build for my track bike.

Obviously any 24H rim will work on a rear 32H hub, but the old Zipps were plentiful and shouldn't be too expensive. They were the first commonly available rim, and they came in 24H since they only sold rims for a while (their original hubs were pretty bad).

cdr

I'd just save up for the disc. It seems pretty easy to find something used but pretty nice for $500, and you can get something not as nice but usable for significantly less. Once you get something decent, you won't have to upgrade, so it's an investment. And if you've already got a fast front wheel, that's most of the time advantage anyways.

I know. I am thinking about it... I can disassenble my road going Corima anyway.

Yeah ultimately it will go that way... but being one month from my planned race, can't be possible. On the other hand, if I build spoked wheels with either the Campy '96 or Corima (probably would go corima), I'd just have to spend on spokes. And spend the rest on my diet, other small equipments, etc.

Thanks for the advice anyway... ;)

I just realized, you're in Taiwan. Do you have any industry contacts? Get some blem rim for cheap? Meaning a nicer one, like a carbon one.

cdr

Well... big brands have their stuff OEM'ed in Taiwan doesn't mean that you can get them commercially on a retail basis.

And I did a bit of calculations today... seems like I have to prepair different spoke lengths to go a 32-24? The variance didn't seem neglectable...

I understand that, but it seems that there are a lot of folks that, say, race for a team or ride with a club that's somehow associated with a manufacturer or something.

My viewpoint is very biased since the folks I know in Taiwan are there specifically to work with manufacturers. So I have a 100% hit rate of people I know in Taiwan and people I know in Taiwan who have industry contacts.

Not sure on the spokes. If you have MS Excel, there's an excellent spoke length calculator available online. You just have to remember to change the spoke count from 32 to 16 to calculate the right and left side lengths.

http://www.sheldonbrown.com/rinard/spocalc.htm

I used that to fiddle with the idea of lacing up a 24H Zipp 440 (old rim) onto various 32H hubs. I ended up building it as a front.

cdr

Won't go. You cannot have a balanced 24-32 wheel with normal crossing to have even spoke lengths. The variences are like +- 3mm for a two cross.


The closest you'll get is to go "crow's foot", which will leave you to 2 different spoke lengths (instead of 3)... but doing it this way is essencially like going 16 spokes (in the rear wheel!), only adding on 8 radial ones to aid the lateral stiffness. Not too sure about this configuration to withstand a standing start...