lsberrios1 

Hello guys,

Today i did my firtst time trial. Although i have a very nice road bike i dont have a tt bike. I didnt fare so well. Got 4th out of 8 rider in cat 4 but there was almost a 5 min difference between me and the winner. I know the tt bike wont even get me close to that but i am wondering how much better i would have done, if any, if i had a tt bike. I averaged 22.8 mph over 20.2 miles at 270 watts average and 1250 feet of climb. I tried tucking in as much a possible but the first place averaged about 25mph! He was riding a pinerello tt bike with the sky team livery (not that it matters) and he was part of a team...

What difference if any would a tt bike make?

grwoolf

Get some clip on aero bars. You will get about 90 percent of the benefits of a TT bike.

hueyhoolihan

impossible to tell. attaining the position is paramount at 22-25 MPH, IMO and can be significant. i'm not so sure that a TT bike is absolutely necessary to do that. OTOH, i know the sky livery is cheaper than a new bike.

DinoShepherd

Great question. The data is clear on the aero part.

The data seems less clear as to how much a rider needs to train in the aero position to be able to use the aero gain effectively. Meaning a rider may put out less power on a TT bike because he is not used to the position.

This would, of course apply to hacks like me who do a TT once a year and not da proze... :-)

Bunyanderman

There are a lot of studies that have been done, and there is a lot of improvement that can be made. One was done with a rider who rides 40km in 48 minutes (very fast).
At this rate, one would save over 2 minutes with proper tt bars.
Another minute faster if they "tune" your position via wind tunnel.
40 seconds from the best front wheel, 30 seconds for the rear.
A measly 17 seconds from an aero frame. This is about 5 minutes over 40km (with an insane speed), and only with a bike upgrade.
Source: Biggest Bang For Your Buck In Time Trial Equipment | CyclingTips

Dunbar

How aero is aero? - BikeRadar

TrojanHorse

I reckon NOT having a TT bike saved you about 4k.

Thank me later.

That's a terrific effort on your part though, congrats.

link0

I would guess you would average 2mph faster on a TT bike, assuming you get comfortable with the changed position first.

Edonis13

Take this with a grain of salt, but the clip on bars make a significant difference for her:

https://www.youtube.com/watch?v=LMLK...CKR97t&index=2

gregf83 

Provided your position is good you should be able to do a 40k tt in under an hour on 270w. There was a thread on Slowtwitch a while back where riders listed tt times and power and my recollection was 270w was on the high end for 25mph.

StanSeven

From the studies mentioned above plus some others I read, two mph is in the ballpark.

From my own personal and non-scientific experiment, two mph difference is what I get between my tri and road bikes over the same course multiple times.

Stucky

My Venge has most of the "aero" features of a TT bike. I notice no difference just riding the roads/JRA between my performance on it vs. my old Klein (not that I was expecting any- I just like the way the bike looks). If you count seconds and race...then it might ave you 2 or 3 seconds; if you're racing others who are on aero bikes, it'll give you the same advantage that they have; but considering that our bodies are the primary drag when riding, I think one's position is the primary factor in being aero.

StanSeven

The OP is talking more than an aero frame I think. Normally a TT bike has bullhorn TT bars, deep aero wheels, steep seat tube or at least a forward leaning post. Granted an aero frame itself just saves a very few seconds per mile

lsberrios1 

Thanks for all the responses guys. Sorry i havent had time to answer individually. Yes I am speaking of a full tt bike. 2mph seems like a whole lot and that would have placed my up in the podium easily. Well at least it seems like engine is pretty well tuned now it's all about tunning my bank account!

gregf83 

Like others have mentioned you can get most of the benefits with a set of clip-ons and an aero helmet.

Stucky

I kow. I think the bars and position that the geometry allows are the real substantial differences- but you can get pretty close on some road bikes by changing the bars.

asgelle

Brilliant. Now would that be 2 or 3 seconds out of a minute, an hour, five hours, what?

As to the body being the primary source of drag, so what? I still need a frame to ride a bike and that added drag can be reduced through judicious equipment choices.

rpenmanparker 

Are you sure. That is approaching world record time.

Bunyanderman

- These numbers are calculated for a rider over 40kms at a time of 48minutes. Faster than most of us could go!

Silvercivic27

Seriously, if you want real answers to this question, ask in the racing forum.

gregf83 

They're just basing it on 50kph wind tunnel data.

pdedes

so a quick change in your road bike position to give you a bit of aero advantage on your road bike. seatpost up 5 mm, forward 5 mm and clip on aero bars.

RChung

I disagree with the ordering and magnitude of the effects in that article. In our testing shoe covers are rarely an improvement, aerobars/position are #1 , and the others (including good clinchers with latex tubes) are somewhat below that.

GhostSS

1989 Tour de France - Wikipedia, the free encyclopedia

RChung

And, to address the OP's question directly, we've measured a difference between a guy in the same TT position with the same clothing and the same wheels/tires on a pretty aero road bike frame and a dedicated TT bike frame. That is, we held his position and equipment constant, including aero bars, and only changed the frame he was on. The difference in CdA was about .02 m^2 (roughly equivalent to 2 sec/km at TT speeds). This was backed up later when he repeated a 40 km TT on the same course with the new bike. We have power meter and weather data for both TTs. He was about 2 minutes faster overall, but he put out slightly more power the second time and the wind was slightly more favorable on one of the legs. When adjusting for power and wind, we estimate that the frame was worth about 75 seconds of the 2 minutes, or just about what we had estimated.