Triathlon - Aero Wheels - What makes a bigger difference?

If I were going to slowly upgrade my wheels to Aero wheels buying one at a time, what makes a bigger difference in aerodynamics......Front or Rear wheel? And is it more beneficial to have a slightly larger rim depth in the rear than in the front (ie: Zipp 303 in front, and Zipp 404 in back)?

AND, does buying just a rear or just front even provide enough benefit? In other words, does it make sense (i know it does financially) to upgrade one at a time?

My Cervelo P2K has the stock Vista rims on it.

They aerodynamics of the front wheel matter more, If you only had the money to buy one, it would be a front wheel. The reason that all the pros use deeper rims or disks in the back is a control issue. there is a bigger aerodynamic gain from bigger rims (or disks) but to use that on a front wheel in windy conditions would be suicide. the only reason the front rims are not as deep is because otherwise there would be a lot of crashes in crosswinds. if you were on a budget, buy a front and possibly a disk cover for the best aerodynamics.

The other reason for shallow rims is hill climbing, on a hilly course, you do not want to try to push on a disk wheel.

I don't know what your price range is but (seeing as you mentioned zipps) a 404 front and 808 rear is a great all-around combo, or an 808 front and 900 disk rear for flat courses without huge crosswinds, or similar ideas from other companies if you are not at that price level

Great explanation! Thanks!

if you were to ride with a front aero wheel and a regular stock rimmed rear you'd look like a tard for not much improvement since the front and rear work together in the whole scheme of things. you'd be better off spending the money on tunnel time to improve your position and get the wheel package when you can swing them both.

the real reason nobody uses a disc front is because it's illegal (in tri's any way)! back in the day they were used often. control is an issue, but some guys will sacrifice control (and their well being!) for aerodynamics - or what they think is aerodynamic any way. i could be wrong but i think they had tunnel numbers in inside tri magazine showing the disc was less aero vs a shallow/deep combo like the 404/808. plus you lose time and efficiency trying to fight the damn thing. there's some vids on youtube of guys being jostled around when wind hits a front disc. it's not funny, but it is.

I agree w/ the "tard" look....which is why I asked b/c I've seen people w/ stock front, and aero back.

That's why i recommended an aero front and a disk cover rear.

although i disagree on the not much improvement, you would probably get 60% of the total benefit from two wheels even if you just had one up front and a stock rim in back, switch that to a disk cover and you would be at 100%

but yes you would still look like a tard if it was just a stock rim in the back.

and as for your front and rear wheel working together in the scheme of things... this is wrong.
1. the air coming off of a wheel (say below the bottom bracket because that is the only place where there is not something else between the two wheels) evens out much to quickly to be affected.
2. above the bottom bracket, the air coming off the front wheel interacts with the downtube, then that interacts with the seatpost (well unless you have a kestrel) and that air interacts with the rear wheel. by the time that air hits the rear wheel, its primary directing force is the seattube and any crosswinds.
3. the front wheel is RARELY in exact alignment with the rear wheel
The front wheel is the leading edge, it cuts through undistrubed air and is the more important wheel.

there is a bigger aerodynamic gain from bigger rims (or disks) but to use that on a front wheel in windy conditions would be suicide.

Having ridden a Blackwell 100mm front wheel and a 108mm-deep Zipp 1080 and having lived to tell about it, I assure you that "suicide" is a bit of an overstatement.

save your money and get an aero helmet. definitely more of an aerodynamic advantage as your body accounts for about 70% of your drag on the bike.

So save some cash and go with the aero helmet