My TT bike is about 30-40w faster than my road position.

that's a pretty big physiological ask

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Brian Stover USAT LII
Accelerate3 Coaching
Insta

Best bike split will give you a very good answer

Geez. That’s huge!

^^ this

But the OP needs to be honest in his assessment of how much time he stays in aero position

Truth is, I’m not saying aero as much as I should. Often, I just ride flats aero and it seems like there are a lot of ups and downs, like Madison IM course as an example.

My fastest split ever was in a 70.3 which was 22.1mph avg

My IM times are MUCH slower as I’m scared of the run. Yeah, I said it. Maybe 16.8mph avg

I have the attitude that I’m riding my bike to the starting line of a marathon, so I don’t try to ride the bike leg fast at all.

Then you should look at "how many watts can I save" vs "how much time can I save".

If you can get in a super comfortable position, save and save a ton of watts, why not ?
Use BBS and see how many watts less would be required to hit the same time.

I spent my entire summer in aero, 98% of my riding time. I can now go forever. I had never done this before.

riding an IM out of the aero position is like running the run with a 10 kilo backpack

You are free to do one of them both of them or none of them. Thats your choice. You can also choose to swim with drag chute or not!

You have to ride it in aero in training.

The team tried a 25mi TT. The guy who has owned ITU bars on his 2020 Propel for chasing KOMs for a year nearly beat the guy who bought a TT bike for the event. Because he rode in aero a lot.

I have seen folks lose a ton of watts and gain no speed due to only riding it once in a blue moon.

If you will ride it weekly all year and race it, buy it. If you will ride it once a month then race it poorly, just put clipons to a road bike.

I have ridden an Airbourne Spectre in aero (race and training) for 20 years! I’m M60-65 and currently have enough headset spacers to provide “zero-drop,” allowing me to stay in aero through 112mi... although I have become more cautious on descents ;-) I’m getting a solid road bike for Fondos, and wondering about using it with clip-on aero bars for both sprint and IM distances. I’ll definitely continue to spend a lot of time Aero on the trainer.... on my old bike. Other than looking better than my beaten-up old Airbourne, what say the Slowtwitch gods?

Riding in aero with a proper fit on a TT bike will save you mountains of time, even on a very hilly course, and even with a significant power output decrease. Probably even a mountainous course. https://www.youtube.com/watch?v=hd0fXhDkH84

My anecdote: Before I left NYC, I did a couple TTs as 4 laps of Central Park from the tavern, careful to pick similar weather conditions, low wind (<5mph), similar temp, pressure, humidity etc. one on my road bike which, at that time, was a masi premiaire and the other on my Felt IA. The times were 1h12m on the roadie and 59:41 on the TT. Given how upright my masi, it is a bit of an extreme. Shortly after leaving the city, I got a huge road bike upgrade in a cervelo S3 and based on a couple shorter segment comparisons between the two roadies, i estimate I would have saved maybe 3 minutes on the S3, still 10 minutes off the Felt.

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808 > NYC > PDX > YVR
2024 Races: Taupo

according to best bike split, a tri bike saves me 36 minutes at the same power

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Yellowfin Endurance Coaching and Bike Fits
USAT Level 1, USAC Level 3

It sounds like you have a tri bike already. Why not just leave it as is.

Buy a road bike and then you can have all the fun and not lose out on the money.

Tri bikes are great for acting like a drag car.
Road bikes are fun for acting like a go cart.

Get a used road bike and do a few maintenance options. You will not lose and investment over.the next few years while you figure it out.

But dont think bringing a road bike to a triathlon will be a good idea or you will enjoy the race just as much.

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Technique will always last longer then energy production. Improve biomechanics, improve performance.
http://Www.anthonytoth.ca, triathletetoth@twitter

Its not absolute that a tri bike is faster. Don't forget last years pro 70.3 WC winner on road bike with aero bars.

https://www.slowtwitch.com/...ustav_Iden_7435.html

I knew someone would say this??? geez. the athlete in question even said he didn't have a TT bike but of course would have used one instead and would have a better result if that was the case.

also his road bike position is perfect in aero , and for that race had little impact for that particulate course and he is one of the best in the world.

Can we stay on topic of the OP instead of always giving single instances to be knowledgeable, or turning it into Lionel here on Slowtwitch.

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Technique will always last longer then energy production. Improve biomechanics, improve performance.
http://Www.anthonytoth.ca, triathletetoth@twitter

But but N=1 is The Best Proof....EVER! <- pink

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Brian Stover USAT LII
Accelerate3 Coaching
Insta

I was curious about this question so in the summer I road a 30-mile loop near my house on my road bike with clip on aero bars and my Trek SC. I put out two watts more on the road bike, so quite similar output. The time difference over 30 miles was 6 minutes 29 seconds faster on the SC. That’s around 23 minutes over 112 miles.


But I wouldn’t call the SC free speed given its price tag.

Greg

(1) that course is an outlier
(2) Have you run the calculation to see if he would have been faster on a tri bike even on that course?

i can sit up on my tri bike from aero, try and maintain the same speed and observe around 30w more. thats tell tale for me.

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80/20 Endurance Ambassador

Actually if you read the slowtwitch interview he said his time trial bike was old (2011) and heavy, plus comfort on his road bike. The course is an anomaly as well. I was just stating that there may be instances for certain athletes that it works out better on hilly courses. Maybe 1 in 1000 but still exceptions. Watched this race live and announcers made jokes about his setup and didn't think he had much of a shot but look what happened.

However your whole response sounds a bit triggered so don't expect a logical reply to this.

Technically, you can attain a similar aero position on a road bike as a Tri bike. You can easily adjust the effective seat tube angle by adjusting fore- aft of the seat. So, is it the bike, or the position you are riding in???
At least 50-60% of people I see on their 5k - 15k Tri bikes are sitting up most of the race :-)
As noted, Gustav Iden had a very good Aero position on his road bike, as do many ITU athletes.
I intentionally have very similar geometries set up on my road and Tri bikes- and have very little difference in the average speed I ride on either bike.
Another example is hilly TT time trials, riders on road bikes often beat riders on TT bikes.
Without question, a 30 watt difference between 2 bikes is much more about the position they are set up for, than the bike :-)

Totally agree. I guess this years TDF showed that it’s worth it to switch to a roadie on a hill during a TT. Definitely an exception and not the rule.

Directly to the OP: if you have the identical TT position between your tt bike and road bike, then you won't save all that much as it comes down to cabling and tube shapes, bars etc. Most of the drag is your body.

If you are using your road bike in a more conventional road fit, even with some clipons, you can be losing many minutes over a long course.

It really comes down to the position your bike allows you to get into, and you can hold for the duration of the event.

I have a very aggressive road bike fit, and in my best road bike tuck it takes me about 300 watts to hit a sustained 25 mph, but on my tt bike I can do the same at about 260 watts.

I'm also more comfortable on my TT bike for longer durations, as my back can rest more as I'm more directly supported by my upper body skeletal structure, I've also put in plenty of time on a TT bike.

YMMV

This is because they were trying to save weight and it was a net uphill from the bike change onwards. But if it is hilly with no technical descending, then the aero position of a tri bike will always be superior. I now people used Gustav Iden at IM70.3 Nice, but Fredrick Van Lierde has won IM 140.6 Nice on his P5 with the fastest bike split.

In any case its about the position more than the bike. Marc Hirschi on his Cervelo Aero Road frame blows 99% of the people on this forum away for his position