TT bike vs Road bike speeds?
 

I've never had a time trial bike, and I am curious how those of you who ride both road bikes and TT bikes would answer this:

- On a flat road, no wind, at the same effort level, how much faster do you go on the TT bike as compared to the roadbike? Assume you are riding with intent and purpose, not just noodling along.

The reason I'm asking is, I'm thinking about riding STP 1-day next year, and wonder if using a TT bike would allow me to ride it solo, not in any paceline, and still make good time. I've ridden STP 2-day a couple of times on a roadbike.

What if I told you that you could ride STP on a road bike... in one day.

And then ask yourself if you want to be on a TT bike for 10-12 hours in a row. Most people would probably say no. Stick some aerobars on a road bike if you want a change from the usual.

Most recreational riders could never adapt to the position pro road race bikes require these days, much less that of a TT machine which is highly specialized even for the elite.

If you are concerned about going faster/farther don't expect a technical solution to a fitness issue.
Go for a well designed program & seat time, it's not about the hardware and never has been.

-Bandera

But suppose he could adapt to the position, and wouldn't mind being on the bike 10-12 hours. What's the answer, how much faster?

It's not the position, really. One can adapt. It's that the brakes are on the cowhorns and the shifters on the aerobars. This is just not a good situation unless you leave early and the big groups never catch you because you are averaging over 20 right from the start. I run aero bars, but I spend the most time on the hoods. It's 10,000 people, of which about 2,000 are one-dayers. It's more reasonable once you clear Centralia, but still. They're designed for riding on closed roads where maybe you catch your minute man and maybe you don't. I've seen a rare guy on one and it always creeped me out. They didn't seem any faster than I was, just younger.

Better to ride a road bike with a slammed -17° stem and clip-ons.

I've done my fastest times solo, which doesn't mean always riding alone in the middle of the road, passing everyone. No, what you do is go like stink from the start and then ease off and start catching groups that go by you at ~2 mph faster than your all-day solo pace, then just move from group to group as the day wears on, with periods out in the wind between groups. Most groups can't keep it together and the ones that can mostly go too slowly. The main thing for a fast day is only stopping every 50 miles, and keeping those short. That's the challenge right there.

With a comfy position on my road bike, in normal road biking gear, 200 watts gets me ~19mph on a smooth flat road. On my TT bike, which has a fine tuned position, + all the aero goodies (skinsuit, helmet, disc cover, etc), 200 watts gets me ~25 on the same roads.

Of course, clip-on aerobars + all the aero goodies on the road bike puts me up to ~23.

You wouldn't want to ride STP on a TT bike but that's because of the crowds. Don't believe the stuff about regular riders can't get used to a TT bike. It's not that difficult and just takes some training miles and maybe a little stretching. Triathletes do centuries on tri bikes which generally are more aggressive and that's sandwiched between a 2.4 mile swim and a marathon.

It took me maybe 4 or 5 times out to get used to the position. Then I did a 50 miler.

Good info there.

cheers

I use clip-on aero-bars on my roadbike and the more aerodynamic position allows me to ride at about the same pace as I do in a group around 22-24mph on 3-4 hour rides, and it's quite comfortable.

On STP I ride in the drops most of the time, so I don't mind being low, if that helps one adapt to a TT bike.

The point of this would be to avoid the groups entirely. I ride in groups, the free speed is great, the scary moments when someone ahead creates a chain reaction are not so great. Maybe a different kind of bike would get me the speed without the sketchy ad-hoc groups, is what I was thinking.

I am consistently 10% faster on my TT vs. my road bike. if I hold 20 on my road, I hold 22 on my TT for a given set of conditions and course. I have much fewer miles on my TT (about 1000) vs. my road bikes, but ride similar courses and generally see this result.

A 6mph difference? Are you pulling a parachute in your road bike?

Uhm, I'd like to see the power files on that. Admittedly I'm big for a cyclist, and not terribly aero, but I can do about 23.5mph in a 40k Merckx style TT and around 25mph, on the TT bike with disc, etc. and that takes me more than 300watts.

25mph out of 200 watts is increadibly aero, and a 6 mph difference from a good position in the drops on a road bike to a TT bike would be an awful lot.

If you use Kreuzotter, for an average size rider it gives you 21mph for 200 watts riding in the drops and 22.2mph on a tri bike. (admittedly that doesn't seem to consider a disc wheel, skin suit, etc, but those things wouldn't take the difference from1.2mph to 6mph).

I'm a small guy, 5'7 and 120lbs, even with a really high w/kg I don't make much power, so I make up for it by field testing everything I can to tease out those extra watts, using aerolab in Golden Cheetah I've got my (estimated) CDA down to .205 on the TT bike. On the roadie it's my all day comfy riding position, so that would be sitting up on the hoods, the difference goes down if I'm deep in the drops, and goes down farther when I'm on the clip-ons, I should have specified that in the original post.

For a demonstration of Time Trial bikes in their native environment:

2014 TdF Stage 20
Individual time-trial Saturday, July 26th Bergerac > Périgueux 54 km

-Bandera

Serious question. Why even bother with STP then? Don't be like the guy who showed up on a TT bike with disk wheel this year. If you want to do a 1 day, start early, ride with the fast guys at the front. They know what they are doing. Consider finding a group of similarly skilled riders. I did it with a group of 8 friends and we had our own paceline for most of the ride, not much sketchiness there.

A few reasons. 1. I don't have 8 friends who want to ride the 1 day. With some lobbying, I might have 4, and we wouldn't all be matched in speed/endurance. 2. Riding in a paceline for awhile is fun but hours of it is not fun, too much concentration required. 3. Eventually, someone touches wheels and goes down. Two of my friends did STP 1 day this year, they were both sent to the ground by someone in the line, one was able to finish but the other was done. 4. Just seems interesting to ride it solo.

I would say that the 1.2mpg gain is generous, but even if it were 2mph, I wouldn't ride my TT bike that long. Loads of Ironman guys do it, but after a 10mi TT course, I am ready to get off the TT bike and set it on fire and throw it off a cliff. I'm still working on my position, can you tell?

why do you sign your posts?

They were sent to the ground by someone else? Usually only the guy who's front wheel touches goes down. Care to expand? Riding for 12-14 hours by yourself during a group event sounds pretty anti social...

Someone braked, following rider went down, then the next couple following riders down. Sounded like your basic paceline pileup.

Back on topic, I found this test report: http://www.specialized.com/OA_MEDIA/...ch%20FINAL.pdf

80% of aerodynamic drag comes from the rider, so the objective of a TT bike (rather than itself being aero) is to help you achieve a more aggressive aerodynamic position which may be impossible on a road bike, even with clip-ons. the effect on speed is going to depend on a) your power output and b) how much of a difference the position change makes to your drag ... and so it's very difficult to give a good answer. as a guide though 2-3 mph of difference is not unusual.

Same reason that I use capital letters, aerodynamics.

-Bandera

cool

~me

The STP can be done in one day solo cruising at say 16-17 as long as you limit stops. My buddy did in 15 hours solo (dislikes pace lines for the reasons above, particularly given the stop lights, many other riders) total time and he kept an easy pace (of course he rides 10K-13K miles a year) and he dogged it at a few stops (I saw him hanging in REI Kirkland before 7 am and asked him "What the hell you doing here, I thought you were headed to Portland?"...never saw him again). As an aside on the STP...my group left early on Saturday (that start was SNAFU as I suspect the organizers wanted as many out as early as possible and one day and two day riders needed up leaving as a bunch) and Sunday we left at 3:30 from Chehalis and we rode under a full moon (we all had lights) and that first 4 hours was a gas. Of course...food wasn't even available at Lexington at 7 am :notamused:... I talked to a few one dayers at Holladay Park in Portland, they left at 4 am (unofficial of course...but whose counting?) from the UW start on Saturday and they avoided thousands of riders and only got passed by serious pace lines who couldn't officially leave till 4:45 at the earliest.

Next year ear will be my 4th STP and I'm seriously thinking of leaving Seattle at 3:30 to enjoy that early morning light.