RoadBikeReview.com's Forum Archives - General


Archive Home >> General(1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 )


Time Trail wheel, which to get first, front or back?(22 posts)

Time Trail wheel, which to get first, front or back?GixxerRick
Sep 11, 2003 11:27 AM
Since i am a poor indivdual, i cant afford to get both wheels at the same time for my time trail bike, which wheel will provide the greatest advantage, a front aero wheel, or a rear disk? which one would you guys get first, if you had limited funds? Any particular brand of wheel??
front deep Vandy02
Sep 11, 2003 11:29 AM
But you're bottle in front of the rear tire and check Cobb's page.
A front Tri-spoke for calm weather and a front V(not veryMR_GRUMPY
Sep 11, 2003 11:38 AM
deep) if it's windy. I have a hard time with a Tri Spoke in the wind when I'm on aero bars. I hate getting blown all over the road.
front! rear wheel drafts the front.... nmClydeTri
Sep 11, 2003 11:51 AM
nm
Front - Buy used from ebaybimini
Sep 11, 2003 12:29 PM
Everything I have read is the front without question. The rear is shielded by the seat post and the air is already turbulent.

Since you are dealing only with the front you are not constrained by Campy vs Shimano or 8,9, or 10 speed compatible hubs.

Good deals can be had on ebay. True Aero (50+mm) is a lot more important than weight in TT (Unless your climbing a mountain one way).

Zipp, HED, HED TriSpoke, Aerospoke, etc are all good. From what I have read the Trispokes are the lowest drag for a front (but can be tough to control in high winds).

I just bought a set of Aero wheels on ebay. A Campy Vento front and a Campy Shamal rear. Aluminum and a little heavy but fast and true. ($200 for the pair).
Thats all wrong ! ! Disk wheel is MUCH more important !CARBON110
Sep 11, 2003 12:51 PM
Many tests prove a Disk wheels more important then an aero frame much less an aero front wheel. A Disk wheel will add more then 2 mph in windy or clam conditions. Belive me, despite what it may appear to be true: a front wheel hits wind first and back is covered by frame etc etc a Disk is much better. Look at alot of the pro TTs and go to steve Heds web site on this subject. he can attest to it. One of the only TTs Lance ever lost in the TDF was to Santiago Botero who used a Shimano front wheel (30mm deep) and a disk in the back. Always disk before front wheel.
from the HED website FAQPmbH
Sep 11, 2003 1:06 PM
Q. I can only afford one wheel, so which should it be?

A. The front wheel breaks the wind first, so this is the most important of the two. In certain conditions, a front wheel will save twice as much as the rear. However, it also depends on the model of wheel, because a rear disc will provide at least as much performance as any other aero design on the front.
Exactly!CARBON110
Sep 11, 2003 1:24 PM
----However, it also depends on the model of wheel, because a rear disc will provide at least as much performance as any other aero design on the front---

Lets say you bought a Zipp 404 for the front. Now Zipp 404s are the deepest front wheel you can get at 58mm deep (outside the wheel Beloki used in last years final TT in the Vuelta ) This will not add as much performance as a disk will in the back. A Disk wheel channels the air more then anything else since it covers the entire wheel. When the wind is blowing you can even go faster with the correct disk. Zip and Hed are the for most leaders in Disk wheels. When you get hit by a cross wind you can actually watch your speed increase on your computer sometimes. However, they are much harder to handle but practice can solve that. Hed makes a clincher Disk by the way. I recomend a tubular
Not very "exact" . . .Look381i
Sep 11, 2003 1:58 PM
The expert answer cited is extraordinarily poorly worded and therefore confusing:

Part 1: "The front wheel breaks the wind first, so this is the most (sic) important of the two."

That seems to tell us that we should focus on the front wheel first -- get the aero advantage there before worrying about the rear.

Part 2: "In certain conditions, a front wheel will save twice as much as the rear."

Wow! That's how important it is. We can expect up to twice as much performance advantage from the front.

Part 3: "However, it also depends on the model of wheel, because a rear disc will provide at least as much performance as any other aero design on the front."

Whaaa? So, if we mount a disc, we will actually get more performance advantage than -any- front design.

Part 1 again: "The front wheel breaks the wind first, so this is the most (sic) important of the two."

It's a non sequitur now . . .

Are they really trying to tell us an extremely aero front can be as important to performance as a rear disc? I know that is not what they actually say, but given the answer makes no sense otherwise, is it a reasonable possibility?

I ask this, because I see a lot of (non-pro, non-Olympic) track cyclists competing with a deep rim front and a standard rear rim. I see fewer with a rear disc in any combination.
Very Lucid and very good points !CARBON110
Sep 11, 2003 2:07 PM
I think the only reason you dont see many disks at all on local tracks and velos is money. You can use a standard wheel on a track bike on the front but you need a track specific wheel on the back. However you pointed out the vague answer to the FAQ. Good post
Here's my translation . . .Drone 5200
Sep 11, 2003 2:18 PM
This is what HED meant to say:

You had better buy a front AND a rear wheel. One is good,
but two is better.

Trust us, we're the engineers.
Disk wheel can make that much of a difference ??Bill from WPB
Sep 11, 2003 1:18 PM
2 mph faster ? Whoa ! Now if that is true, that means that I can improve almost two minutes from my 10 mile TT personal record ! That means I wouln't suck anymore !! Is this really possible ??
2 MPH?? I wish (nm)Chen2
Sep 11, 2003 1:27 PM
I tell you what..........ProofCARBON110
Sep 11, 2003 1:49 PM
I use a SRM power meter. I will get together with my coach over the next week and plan a test. I will use the local Velodrome as the battle ground. My first test will be on Caene Creek Tubular Carbon 44mm deep (Zipp rims)wheels. It will have to be configured by distance and time? Second test will be done with a disk on the back. I will upload the SRM file to the board. Im sure I can figure out a specific test that will minimize the variables involved and I will pick a day where conditions are preferable for said test. Let me think about it and find a good time for it next week. Sound good?
I tell you what..........ProofBill from WPB
Sep 11, 2003 2:02 PM
That sounds great! I would appreciate you posting your results. I'm pretty new at this and have only done six TT's this year (first year). No disk wheel,... I'm broke after purchasing my Cervelo P2K. I love this sport and if the improvement can be significant, well hell, I'll go broke again ! (:>))
I tell you what..........Proof?Al1943
Sep 11, 2003 5:16 PM
I don't know. Take a look at the info on drag coeffients comparing disk whiles to aero wheels. I really do hope you are right because I'm trying a disk at a time trial on 9-22. Sorry, but I think 2 mph is way optimistic.

http://analyticcycling.com/

Al
Meaningless, unless you don't know which is which....TFerguson
Sep 12, 2003 7:10 AM
Actually, your coach (or anyone else you come in contact with) would also have to not know. Unless it's double blind, it indicates nothing. Even then it proves nothing.

TF
John Cobb thinks disk..dotkaye
Sep 11, 2003 2:37 PM
in a recent interview,

http://www.roadcycling.com/news/article319.shtml

"How can an average racer get the most "bang for the buck" to increase aerodynamics and lower TT times?

Use aero bars and get a disc wheel."

But I always thought front was more important, too. This is interesting.

Incidentally, you can get a Renn disk for $319 new, www.rennmultisport.com I think. That's not bad at all. For the front, shopping ebay for any of the deep section fronts, Zipp, Hed, etc, you should be able to get one for $150 or so. I paid $100 for a Zipp 440 in good condition, been very happy with it.
No contradictionasgelle
Sep 12, 2003 6:28 AM
There's no contradiction here.

Given the same style wheel: deep rim, trispoke, disk, the aero benefit is greater when that wheel is located on the front rather than at the rear.

However, since there are problems associated with running a disk wheel at the front and so it is rareley done, putting a disk at the rear is more effective than placing any of the other style wheels at the front.
Back, in the real world...Tri_Rich
Sep 12, 2003 6:29 AM
The front wheel may well have more impact on the aerodynamics, but a front alone will make the bike handle poorly particularly in any wind. The deep rim/disc on the back will balance out the handling if you have both.
Tri Rich.........CARBON110
Sep 12, 2003 7:41 AM
How did Biltmore go? It was a good day for it. I was out on the parkway with friends and didnt make it over there until late.

TFerguson,

I don't see how its meaningless. Its a harmless test and if it shows anything it will be informative. As long as the same; distance, cadence,speed,power,Hr within 5 beats, and conditions are the same. Its about as controlled an enviroment you can get outside. A disk really shines though when its windy.

Just a premature idea of what I was thinking:

-10-20 miles
-100rpm
-20mph
-Medium to Light HR
-Light power so no fatigue on second test
-Start both intervals at speed 20mph
-no aero bars BUT maintain same postion in drops/or aero bars entire time

Any other suggestions? We should all agree on the test and if someone out there has a simlar set up with a SRM or downloadable computer...lets do two tests. It will most likely be done on a calm morning to avoid any wind that may develope.
Carbon 110...Tri_Rich
Sep 12, 2003 10:53 AM
Biltmore was very nice, but the hills were brutal early in the bike course. The location was gorgeous, which was a real plus as I had both my parents and my in-laws who live in Waynesville with me. After the race we took off and went ot the Old Europe bakery on Wall St. Unfortunately we left early and I missed out on my age group medal, oh well.

As for your test I would think you could either keep the power constant and look at the speed or keep the speed constant and look at the power. Also I might think about doing the test as disc/no disc one week and then no disc/disc the next.

Personally I have a Renn disc and ride it for all races, even the Biltmore race.