Time trial fit

A light bike doesn't replace good fitness.

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Kermithimself
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Location: Denmark

by Kermithimself

Got a TT bike, and now fiddling with the setup. Any ideas as to how start with this? As of now I have my saddle pushed forward to 50 mm behind the BB, and about the same height as my roadbike. Are there any rules of thumb how to go about this?
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LSiena0206
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Joined: Thu Mar 16, 2006 5:12 am

by LSiena0206

Take some time to get adjusted to the feel of riding in an aero position first - with comfort in mind.

If you have been properly fit on your road rig, that seat height would be a good place to start. If you are not planning any races any time soon, don't concern yourself with the 50mm nose issue - most of my local race officials don't concern themselves with that detail.

Take a set of hex wrenches with you on your rides and adjust as needed. You'll know when something is out of adjustment, and you'll know when you hit that comfort zone.
Once you reach a comfortable fit and have tried out a couple hard VO2/LT workouts and a few long rides, then take it to a fit-pro and have the "aero-ness" adjusted : ie bar height/length/saddle height.
A good fit-pro will take your flexibility into account and that will take some time in the aero position, and that may take some ride-time.

Good luck and enjoy - when it's all done properly, you'll be able to ride for hours.

by Weenie



Ghost234
Posts: 422
Joined: Sun Apr 24, 2011 2:21 am

by Ghost234

One thing I've often done at my shop when fitting someone to a TT bike is take the seat height from the road bike and apply it to the nose (where you will likely be sitting) of the saddle. Most people during a TT will slide to the front of the saddle, so it will help a bit with proper leg extension. Also make sure the seat is level - I've seen many riders DQ'd for a tilted saddle. It also helps if your saddle matches the one your ride on (ie. Antares for road, Ares for TT)


Next, make sure the aerobars are LEVEL. Ideally speaking you want 2 90 degree angles for the arms. One from the shoulders, and one on the elbows. If you are slightly past 90 degrees that is fine, but never exceed it significantly, and I wouldnt suggest going below 90.


Extensions are very personal. I like S bends, but I know many people prefer ski bends. It really depends on you, and what you fine comfortable. You ideally want to extension to end just at the end of your hand or just slightly past (index finger touching the shifter is the furthest I'd go.)




Some other things to remember:
- From BB 75cm to shifter middle MAXIMUM (or with Di2 to end of the shifter)
- Saddle 5cm behind BB
- 3:1 Ratio

LSiena0206
Posts: 39
Joined: Thu Mar 16, 2006 5:12 am

by LSiena0206

Great advice with the bars.

"DQ'd for a tilted saddle"
Wow, that's harsh. Is that in the rule book ?

Dalai
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Location: Melbourne, Australia

by Dalai

Level saddle is a recent addition to the rules...

Machinenoise
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Joined: Wed Jun 22, 2011 9:39 pm

by Machinenoise

Clarified to +/_3degrees from nose to rear. Like this http://www.bikebiz.com/news/read/uci-to ... 012/012388" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;

All very UCI legal there Ghost234. kermithimself might not be riding UCI races, although he may. Not sure how it works elsewhere but in the UK there is only 1 UCI regulated TT per year (nat champs) Many of the best riders here abuse the rules the rest of the year! Depends on your targets I guess.
I still don't know how they came up with the 75cm from BB to shifters rule its a PITA for 6ft plus riders!

A back angle of less than 15degrees is also a good place to start depending on flexibility. The angle is from a line drawn from the centre of your shoulder socket to the centre of your hip socket, and a horizontal line. Eventually you'll get it nice and flat like Dave Z or others. Extremely low TT positions usually require a lot of flexibility and practise to reduce the power lost by being cramped up and closing the hip angle.

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grid256
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by grid256

What Machinenoise said. Your body will settle into the position both in terms of drop and reach. It will take awhile and you'll notice especially under hard LT efforts the urge to stretch out, push back or pull up if the fit isn't all the way there. Hopefully you didn't get a non adjustable super bike and you have a little to play with!

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Kermithimself
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Location: Denmark

by Kermithimself

Did some fiddling around yesterday, and think I have it dialed in. It's a good starting point at least, but wanted to hear what you guys have to say. The helmet and skinsuit is to show off :lol:
http://youtu.be/4rYSlZzFrN4

Let me hear.
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Juanmoretime
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by Juanmoretime

Arms could be back a little and I assume you can get your stem lower with either removing spacers or a -17 stem. How long are your cranks? I ride 170 on my tt bike and I'm 6' even. It looks like you have quite a bit of knee lift.
RESIDENT GRUMPY OLD MAN.

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grid256
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by grid256

Your arms could be back, but then again, once you roll your hips forward and drop your head, they should be about right. Also, I can't help but think your saddle is too high.

Machinenoise
Posts: 147
Joined: Wed Jun 22, 2011 9:39 pm

by Machinenoise

Saddle might be a touch high, I prefer mine a little higher than generally prescribed so it might work for you.
Helmet looks like it sits too high on your head, maybe try another?

Aero pet hate, hands too low. You are scooping the air into your chest like that. wind tunnel proven to be slower for almost everyone! Bring the top of the hands up enough that the entire forearm is absolutely horizontal. Unless you ride UCI races and have dodgy commisaires.

Looks a pretty good starting point though, a video after a warm up and during a TT effort interval will show a lot more, as your body may choose slightly different positions once fully warmed and working hard. It will also tell you how comfortable it is at the moment!

weeshuggy
Posts: 65
Joined: Thu Dec 01, 2011 4:59 pm

by weeshuggy

Saddle looks to high, looks like you are stretching quite a bit at the bottom of your pedal stroke and although it might be fine now under a big effort i can't help but think it might put a little to much stress on your back ?
if you lower the saddle make sure to get a diff stem to lower the bars, cause you arms look fine other than in my opinion they should be tilted up for aeroness.

NGMN
Posts: 1536
Joined: Mon May 30, 2005 7:13 am

by NGMN

I would say you're close in your video.

Saddle looks high to me, but that is more of a personal preference.

I would say that bars could come up a touch so that your arms are a parallel to the ground or even slightly "up".

I'm not in complete agreement with people who say that you want a 90 degree angle between your upper arms and your back. A little bit larger angle will usually be more aerodynamic. Its why Graeme went to the Superman and why the UCI has an extension reach limit. Generally, a slightly longer reach encourages "rolling" the shoulders in which reduces frontal area and makes a smoother shape to your back. The UCI limit is 75cm from BB to center of shifter horizontally unless exempted to 80cm. I would say only reduce reach for issues of comfort, though I've generally done a fairly long reach without comfort issue in long distance tri racing.

After this experiment with a lower bar height and try to find a good balance between aero and power.

beardking
Posts: 261
Joined: Thu Dec 29, 2011 11:22 pm

by beardking

hey, I just got a TT bike and would like some positional advice too. didn't know if i should post another thread or not, hope you don't mind me posting on here kermit.

Image
Image

and a video link
http://s45.photobucket.com/albums/f91/z ... 155319.mp4

thanks

by Weenie


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