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TT Bikes are much quicker than road bikes

 
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mattsurf




Joined: 28 Sep 2016
Posts: 257
Location: salisbury

PostPosted: Thu Mar 16, 2017 11:45 am    Post subject: TT Bikes are much quicker than road bikes Reply with quote

I know that the question of TT bikes Vs Road bikes gets asked on this and other forums as well as Facebook groups. If you are considering buying a TT bike, I am sure that you have read lots of articles and research that suggests that a TT bike is a little quicker than a road bike, but is a poor return for the investment required. Well, in my own experience this is simply not true, a good, well sorted TT bike is massively faster than a road bike.

After a winter of hibernation I just got my TT bike out on a fabulously still and warm March day. I was utterly blown away by how fast my TT bike is compared with my road bike - the benefits are not marginal, the benefits are massive!

My Specialized Shiv TT bike has undergone some significant upgrades this winter, mechanical shifters have been replaced with Di2, I have a new Quarq Elsa RS power meter, new 25mm Vittoria Corsa CX2 tyres replace 22mm Schwalbe One tyres, and I have a new Lazer aero helmet.

I know that my cycling has improved significantly over the winter, my outings on my road bike over the past 2 weeks have seen me breaking my PB on more than 50 Strava segments, but I was not prepared for the difference that the TT bike would make

Over a 25 mile hilly ride, I averaged 23.5mph, previously I had not bettered 21 mph over this course, my average power was 251W (NP 264W), Average HR was really low at 154bpm and cadence 89 rpm. I was so fast touching 30 mph on flat sections that I thought that I must have had a strong tail wind and that I would really pay for it when I returned.... but this was not the case, if anything, I was even faster on the return. I shattered every single PB on the ride by massive margins. For the first time ever, I was in the top 10 riders over 7 different segments, and top 3 in 3 of them, and these are popular segments with 500+ different riders.

So what makes the TT bike faster, and why do I think that the research is misleading? Simple answer is both power and aerodynamics; I now have power meters on my TT bike and my road bike; last week I road 25 miles on my road bike at exactly the same average HR, but with an average power 12% lower. The difference in average speed was 20%. This suggests that the TT bike is around 20% quicker, 40% of the improvement is due to lower resistance and 60% improvement due to the legs working more efficiently.

The research may be misleading because it only considers the reduction in resistance that you get from a TT bike without considering the physiological improvement in rider efficiency, my rough estimates suggest that the physiological benefits are at least as important as the aero benefits

Or maybe I was just having another "flying" day Airborne
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Jorgan




Joined: 12 Nov 2007
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Location: alles was ich bin, alles was ich war

PostPosted: Thu Mar 16, 2017 12:20 pm    Post subject: Re: TT Bikes are much quicker than road bikes Reply with quote

I don't disagree, but a few considerations though....

mattsurf wrote:
I just got my TT bike out on a fabulously still and warm March day.


Weather has a huge impact, and yesterday was unseasonably good for mid-March. The higher temperatures make it easier for muscles to work, for you to breathe and the air has less density. Added to that, what additional training gains have you made?

Air Density:
5 deg = 1.269, 15 deg = 1.225, 25 deg = 1.1839

Also, body position is the biggest contributory factor to aerodynamics. A good aero position on a road bike (even with round steel tubes), will see you go way faster than a traditional road set-up. Also, what about tyres, are you comparing Gatorskins to GP Siis? etc

All things being equal a TT frame is faster, but it's way down the order of magnitude. I find just jumping from my chunky Boardman CX bike to a carbon road bike makes a big physical & psychological difference Cool
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Last edited by Jorgan on Thu Mar 16, 2017 12:24 pm; edited 1 time in total
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jibberjim




Joined: 15 Aug 2008
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Location: Kingston

PostPosted: Thu Mar 16, 2017 12:23 pm    Post subject: Re: TT Bikes are much quicker than road bikes Reply with quote

mattsurf wrote:
After a winter of hibernation I just got my TT bike out on a fabulously still and warm March day.


Afabously warm and still day will also massively increase your speed anyway - 10degrees warmer alone is probably enough for 1/2 mph, wind is more complicated of course as it depends on your direction, but will likely be worth a load more too.

Of course aerodynamics matter hugely, but then all roadbikes are not the same, I could see the difference between 31kph and 35kph just by going out on my Cervelo R3 rather than a Cervelo RS. (they're set up differently for a reason)

mattsurf wrote:
and these are popular segments with 500+ different riders


75000 is a popular segment, 500 is a lost lane!
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mattsurf




Joined: 28 Sep 2016
Posts: 257
Location: salisbury

PostPosted: Thu Mar 16, 2017 12:28 pm    Post subject: Reply with quote

Weather is probably a factor, although it was also really good last week as well - sat outside at Waitrose after the ride

I have a good road bike, and using Specialized S-Works 26mm tyres on Reynolds 46mm carbon clincher rims. My TT bike uses Vittoria Corsa CX Tubulars on Reynolds 66/88 carbon rims, these are undoubtedly faster

TT helmet also made a difference
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Jorgan




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PostPosted: Thu Mar 16, 2017 12:39 pm    Post subject: Reply with quote

mattsurf wrote:

TT helmet also made a difference


Now we are getting somewhere; this ain't part of the bike Wink
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mattsurf




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PostPosted: Thu Mar 16, 2017 12:58 pm    Post subject: Re: TT Bikes are much quicker than road bikes Reply with quote

jibberjim wrote:


75000 is a popular segment, 500 is a lost lane!


Not in rural Wiltshire

At least let me bask in the glory of being the 3rd fastest out of 500 riders and shatter my illusions later
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Wheezy




Joined: 10 Oct 2007
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PostPosted: Thu Mar 16, 2017 1:04 pm    Post subject: Reply with quote

I've had my TT bike for 5 seasons now and I have got to that uncomfortable stage where I have seen the immediate benefit of transferring from a road to TT bike, dropped my times through more structured training (Trainerroad) and bought the silly hat and skin suit. It's now a case of finding ways to improve further, so I am finding myself looking at 'faster' helmets, 'faster' skinsuits, and fast days on fast courses. (which is all quite expensive!)


My actual bike is a bog-standard Argon E-80 which I find very comfortabe to ride and while I would like to upgrade, I can't really see much point. More consistent training with an increase in TSS without me getting ill in the process is the only way forward now, and if I can find a way of reversing the ageing process, then even better. Smile
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Davem




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PostPosted: Thu Mar 16, 2017 2:54 pm    Post subject: Reply with quote

my non scientific experiment is a TT bike is "about an hour faster" than a road bike over an IM distance

Rationale..

Day 1 of Quin - TT bike - 6:32
Day 2 of Quin - Road Bike - 7:34
Day 3 of Quin - TT Bike - 6:38
Day 4 of Quin - Road Bike - 7:50
Day 5 of Quin - TT Bike - 7:30 (sh!t weather)

I have a similar pattern on the Deca, but you get the gist.
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mattsurf




Joined: 28 Sep 2016
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PostPosted: Thu Mar 16, 2017 3:44 pm    Post subject: Reply with quote

Davem, these differences appear to be consistent with my observation of 20%, I may have got a slightly larger improvement due to better weather conditions and using an aero helmet on the TT bike.

Trouble is, I have not seen any research or articles that suggest that a TT bike could be 15%-20% faster than an road bike.
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Jorgan




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PostPosted: Thu Mar 16, 2017 3:48 pm    Post subject: Reply with quote

It's the position that's faster, not so much the bike.
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