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Old 07-24-04, 07:04 AM   #1
gringorio
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who is faster ... ?

… the TDF pro riders set up properly on their TT bikes or the TRI pros with those funky foreword raked seat posts and awkward positions? It has always seemed to me that road racers have a better position for the TT while triathletes have adopted a poor and inefficient position for the cycling TT. Any thoughts?
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Old 07-24-04, 10:12 AM   #2
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I thought triathaletes position was specific to se different muscle groups in different intensities then the running stages. This way leaving the running muscles for running and forcing a little used set (in comparison to others) for biking, thereby feeling 'rested'....well as rested as a triathelete can feel anyways.
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Old 07-24-04, 10:25 AM   #3
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hadn't thought of that... makes sense.

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Originally Posted by Maelstrom
I thought triathaletes position was specific to se different muscle groups in different intensities then the running stages. This way leaving the running muscles for running and forcing a little used set (in comparison to others) for biking, thereby feeling 'rested'....well as rested as a triathelete can feel anyways.
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Old 07-24-04, 10:45 AM   #4
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The biggest difference between a "road" bike and a "tri" bike will be the seat tube angle (and sometimes the head tube angle), the UCI has placed limits on these dimensions (the saddle needs to be a few cm behind the bottom bracket, which leads to a slack ST angle). There have been a couple of studies done, and riders on a "tri" bike will be faster than on a road bike.

http://www.slowtwitch.com/mainheadin...seatangle.html

This seems to be highlighted as we watch the ITT, there are quite a few riders who ride on the nose of the seat.

Andrew
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Old 07-24-04, 12:29 PM   #5
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Quote:
Originally Posted by gringorio
… the TDF pro riders set up properly on their TT bikes or the TRI pros with those funky foreword raked seat posts and awkward positions? It has always seemed to me that road racers have a better position for the TT while triathletes have adopted a poor and inefficient position for the cycling TT. Any thoughts?
Two words ... "Graham Obree"

Just look at that position and the result and it should be no surprise why that style of bike was banned from the hour record.



-mark
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Old 07-24-04, 01:00 PM   #6
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Quote:
Originally Posted by Ajay213
The biggest difference between a "road" bike and a "tri" bike will be the seat tube angle (and sometimes the head tube angle), the UCI has placed limits on these dimensions (the saddle needs to be a few cm behind the bottom bracket, which leads to a slack ST angle). There have been a couple of studies done, and riders on a "tri" bike will be faster than on a road bike.

http://www.slowtwitch.com/mainheadin...seatangle.html

This seems to be highlighted as we watch the ITT, there are quite a few riders who ride on the nose of the seat.

Andrew
Very interesting.
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Old 07-24-04, 03:01 PM   #7
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My understanding was that TT bikes and tri bikes had essentially the same seatpost angle (i.e., steeper than a road bike).

It was also my understanding that the lost efficiency of a road bike's slacker seat tube is more than made up for by the superior position it offers for seated climbing (ever go up a hill behind a tri-geek?--they're pretty slow)

As for speed, I'd *guess* a pro TT rider would be significantly faster than a Ironman rider because tri-athletes tend to have larger/heaver upper bodies (which means less O2 to the legs when pushing your maxHR). In a local, 10mile time trial here last spring, the tri guys were usually 5-7mph slower than the road racers on their TT bikes)

Last edited by ExMachina; 07-24-04 at 03:08 PM.
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Old 07-24-04, 04:09 PM   #8
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Quote:
My understanding was that TT bikes and tri bikes had essentially the same seatpost angle (i.e., steeper than a road bike).
Not for a UCI event (like the Tour), UCI rules have a limit on how close the nose of the saddle is to the bottom bracket, so the "final" angle is still pretty slack. Look at the Trek TT bike, 73.x degree seat tube angle, compare that to the 76-78+ angles on tri bikes.


Quote:
It was also my understanding that the lost efficiency of a road bike's slacker seat tube is more than made up for by the superior position it offers for seated climbing (ever go up a hill behind a tri-geek?--they're pretty slow)
Well the study above talks about power output and effeciency and how it improves with steep angles, so I can't give you an answer here. The bigger problem may be that a tri-bike isn't always the best climbing machine, it doesn't have the best climbing position on the bars, the components are typically heavier (especially aero wheels), etc.


Quote:
As for speed, I'd *guess* a pro TT rider would be significantly faster than a Ironman rider because tri-athletes tend to have larger/heaver upper bodies (which means less O2 to the legs when pushing your maxHR). In a local, 10mile time trial here last spring, the tri guys were usually 5-7mph slower than the road racers on their TT bikes)
That would make sense, a person who strictly cycles will be faster than somebody that has to mix 2 other sports into the mix. The cyclist will be out on the bike 6 days a week training, the tri-person will only be on the bike 2-3 days of the week.

What would be interesting is to take the same person and put them on both bikes, give them enough time to get used to the positional changes and let them go out and rock and roll.

Andrew
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Old 07-24-04, 04:44 PM   #9
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This years Tour had a the trivia question:
What Profession did Lance Participate prior to Cycling?
and the answer was: Triathalons
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Old 07-24-04, 05:40 PM   #10
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Quote:
Originally Posted by geneman
Two words ... "Graham Obree"

Just look at that position and the result and it should be no surprise why that style of bike was banned from the hour record.



-mark
It's interesting to see the bike in the photo doesn't seem to have steep seat tube angle. Was it on purpose or it was before the research of steep seat tube angle? I wonder if he would make any changes if he was to do it again today. I may have seen another similar photo where he's riding in the crouching position and both arms tucked under his upper body but in little more forward position.
By the way, the shape of his helmet doesn't seem to give him any room to look up to see what's ahead. Did he ride looking down the line for the whole time?
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Old 07-24-04, 05:49 PM   #11
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That's Graham's "x-frame" that he designed himself.

He's on a track, he really doesn't have to pay TOO much attention to what's ahead of him.
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Old 07-24-04, 05:50 PM   #12
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Quote:
Originally Posted by Ajay213
Not for a UCI event (like the Tour), UCI rules have a limit on how close the nose of the saddle is to the bottom bracket, so the "final" angle is still pretty slack. Look at the Trek TT bike, 73.x degree seat tube angle, compare that to the 76-78+ angles on tri bikes.
Thanks for setting me straight. I thought TT bikes were exempt from most of the UTI stipulations, but apparently not the 5cm rule.
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Old 07-24-04, 06:28 PM   #13
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My Tri experience is just about nil so I'll just stick my little toe in the water.

A prominent though not unanimous line of thought for roadbikes is in favor of "slack" (within UCI rules) seattube angles. Perhaps the most prominent spokesperson for this is Greg LeMond who insistently talks about "getting behind the pedals." From a personal view, it works well for me as I was reluctantly forced to admit that I pedalled much better on my mid-line Univega than I did on my Colnago. That hurt.

Fortunately the Colnago fits my wife really well and she prefers the straighter angle and "being on top of the pedals."

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Old 07-25-04, 12:33 PM   #14
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Quote:
Originally Posted by Devil
That's Graham's "x-frame" that he designed himself.

He's on a track, he really doesn't have to pay TOO much attention to what's ahead of him.
On the bike

"He wanted to have a narrow bottom bracket, and since normal bike parts did not allow that, he used the bearings from a washing machine. Because of the narrow bottom bracket (68 mm), he rode almost knock-kneed which reduced the drag also, but a normal frame with standard top tube would not allow that - so he invented an X-frame design.

Since he was on a low budget, he built the bike by himself, using cheap or used parts wherever possible. The cranks contained a piece of metal found roadside, the handlebar was from a BMX bike, but the overall design was just brilliant and perfect for his needs.


Though this position was not very comfortable, wind tunnel measurements showed that it reduced the aerodynamic drag about 15 %, giving a theoretical speed gain of more than 2 km/h at 50 km/h!
"
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