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Slowman says Jens' seat is too LOW...
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Or...Jens gets "FIST'ed". I was lucky enough to be present today during a visit to Xantusia by Jens after the SCNCA district TT. Here is the result of the fitting session that Slowman offered to Jens.

Jens' current TT position (non-UCI legal):



After Slowman was through with him:



The main change was raising his seat by a whopping 2.5cm!

I just thought I'd put them up there and let y'all discuss amongst yourselves...;)

http://bikeblather.blogspot.com/
Last edited by: Tom A.: May 20, 07 8:57
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Re: Slowman says Jens' seat is too high... [Tom A.] [ In reply to ]
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"The main change was raising his seat by a whopping 2.5cm!"
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It looks like the main change was bringing his elbows back by 10cm or so!

Is the new position going to be as aero? I'm guessing no.

Will he generate enough extra power to compensate? I'll guess maybe.

Haim

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"Sometimes you need to think INSIDE the box!" -- ME
"Why squirrel hate me?"
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Re: Slowman says Jens' seat is too high... [Haim] [ In reply to ]
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the new position looks far more comfortable.

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Help my agency save babies. visit our March of Dimes website:
http://www.walkamerica.org/torresagency
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Re: Slowman says Jens' seat is too high... [Haim] [ In reply to ]
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I would agree, the elbows sure look different.

________________________________________________

Pasadena Tri Club
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Re: Slowman says Jens' seat is too high... [vtrader] [ In reply to ]
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Will the elbow pad stay where it is when he sets up his own bike? I would worry about a neuropathy at the elbow.
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Re: Slowman says Jens' seat is too high... [Tom A.] [ In reply to ]
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"The main change was raising his seat by a whopping 2.5cm!"

I assume you meany lowered by 2.5 cm... how did his power numbers compare from old to new?
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Re: Slowman says Jens' seat is too high... [bpq] [ In reply to ]
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no it was raised. look at the saddle top in relation to the 'plate' on the wall in both pics. That being said, I figure the title should have read ".... too low ... "

Any SCNCA State results online BTW?
Last edited by: rmur: May 20, 07 5:31
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Re: Slowman says Jens' seat is too high... [Tom A.] [ In reply to ]
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The new position looks more comfortable. Much less stress on the lats, but is it more aero? The original position was remeniscent of the old superman position:

http://www.wolfgang-menn.de/superpos.htm

Has anyone tried tht Obree or Boardman position in a triathlon?
Last edited by: Dreadnought: May 20, 07 6:15
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Re: Slowman says Jens' seat is too high... [Dreadnought] [ In reply to ]
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In Reply To:
but is it more aero.

how do you know that?
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Re: Slowman says Jens' seat is too high... [alvaro] [ In reply to ]
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In Reply To:
In Reply To:
but is it more aero.

how do you know that?
I don't know that. That's why I brought it up for discussion.
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Re: Slowman says Jens' seat is too high... [Dreadnought] [ In reply to ]
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"But is it more aero?"

I'd say absolutely no. More frontal area (higher saddle, arms angle more acute and elbow pads higher) and upper arms are more cylindrical for starters.

Neither position is UCI legal, and jens isn't doing Tris (so the comfort part isn't *as* important, as you're already horribly uncomfortable from going as hard as you can for a TT).

It'll be interesting to see how his times compare with his other position, with similar and any gained wattage, though (hopefully you'll tell us, jens).
Last edited by: jhendric: May 20, 07 6:30
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Re: Slowman says Jens' seat is too high... [jhendric] [ In reply to ]
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Why are both positions non-uci legal? I can't see his seat nose to see its relationship to bb and the angles of his arms look like they would be ok.
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Re: Slowman says Jens' seat is too high... [bpq] [ In reply to ]
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In Reply To:
"The main change was raising his seat by a whopping 2.5cm!"

I assume you meany lowered by 2.5 cm... how did his power numbers compare from old to new?

It was raised. The photo below should give you a better idea of how it used to be. Too much screwing around with cleat positions and crank lengths got me to there.

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Re: Slowman says Jens' seat is too high... [jens] [ In reply to ]
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Do you have picture of the new position on the Cervelo?

What is size of the bike? What is the seat height? What is the stem length? What is the drop off from seat height to aero pads?
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Re: Slowman says Jens' seat is too high... [jens] [ In reply to ]
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This is a pretty good representation of the before and after (more precisely it's after and before, left to right). the changes were as follows:

1. the "new" jens has a saddle 2.5cm higher.
2. the new and old jens have virtually the same armrest drop, old being 18cm, new 17.5cm
3. nevertheless, jens' hip angle differs between the old and new. the new jens has a hip angle (using my landmarks) of 100°, dead on. the jens-stretch has a hip angle of 97°. the reason is that jens-stretch has armrests sitting 8cm further in front of the saddle, and this places his upper arms at an angle, lowering his front end and making his hip angle more acute.

my guess: unquestionably, in my mind, jens' saddle was too low. but jens-stretch's more acute hip angle may have resulted in hamstring-stretch, mandating a need for a lower saddle height. even accounting for that, i think the saddle was well lower than it ought to have been, and i'd be very surprised if the saddle on his road bike was that low. but it's hard to quantify -- it's hard to measure apples to apples if your road bike has a standard saddle and the TT bike an ISM adamo. the way to check would be to use a goniometer and look at knee angles. in any case, i think the low saddle has more to do with lost power than anything else.

jens-stretch is undeniably more aero than jens-compatto, but i don't know how much. can jens-compatto do something about that head sticking up? would jens-stretch with higher saddle get the watts back? would jens-compatto get more watts back? would jens-compatto get more watts than he'd lose in negative drag-adjusted-watts? i suspect we'll hear more after jens does some field tests.

Dan Empfield
aka Slowman
Last edited by: Slowman: May 20, 07 7:56
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Re: Slowman says Jens' seat is too high... [Slowman] [ In reply to ]
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Thanks for the pics and analysis. Nice use of compatto....one of my favorite road race terms.
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Re: Slowman says Jens' seat is too high... [rmur] [ In reply to ]
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In Reply To:
no it was raised. look at the saddle top in relation to the 'plate' on the wall in both pics. That being said, I figure the title should have read ".... too low ... "

Any SCNCA State results online BTW?
Doh...I totally blew the joke I was trying to make...yep...the title should have said "too low". That's too funny. I guess old habits die hard, huh? I'm going to edit it now.

http://bikeblather.blogspot.com/
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Re: Slowman says Jens' seat is too high... [Slowman] [ In reply to ]
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In Reply To:
3. nevertheless, jens' hip angle differs between the old and new. the new jens has a hip angle (using my landmarks) of 100°, dead on. the jens-stretch has a hip angle of 97°. the reason is that jens-stretch has armrests sitting 8cm further in front of the saddle, and this places his upper arms at an angle, lowering his front end and making his hip angle more acute.

Dan, I was thinking about this a bit this morning (don't worry, it was after my coffee), but wouldn't using the center of the BB as one of your landmarks have made your angle measurement artificially larger on the Jens-stretch position due to his low seat height?

The way I'm thinking is that your angle measurements are valid ASSUMING the seat hight is set correctly and the knee angle is consistent. BUT, in the case where the seat is too low, the relation between the torso and the leg will be more acute than if the seat was set "correctly".

I'm thinking that in effect, he was actually more acute than what you had measured.

Thoughts?

http://bikeblather.blogspot.com/
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Re: Slowman says Jens' seat is too high... [Tom A.] [ In reply to ]
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"Thoughts?"

what i'm measuring is a proxy for the hip angle and, yes, what you say is exactly correct. a landmark more closely approximating the hip angle would be through the femur, and i think tom demerly does this. but i'm old and i've got too many data points invested in the way i do things. furthermore, measuring at top dead center gives you even better data, assuming the landmarks are easy to find and yield reasonable precision.

this means, btw, that jens-stretch with taller seat height yields a more obtuse hip angle at TDC than jens-stretch with lower seat height.

nevertheless it's still true that jens-on-stretch, regardless of saddle height, is worth 3° of hip angle versus jens-not-stretched. what lowering the saddle does to the hip angle must be added to that.


Dan Empfield
aka Slowman
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Re: Slowman says Jens' seat is too high... [Slowman] [ In reply to ]
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Dan,

It seems to me that lowering the saddle opens up the hip angle. what am i getting wrong here?

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Re: Slowman says Jens' seat is too high... [footwerx] [ In reply to ]
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yeah, you're right. not enough coffee in me yet.

Dan Empfield
aka Slowman
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Re: Slowman says Jens' seat is too high... [footwerx] [ In reply to ]
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In Reply To:
Dan,

It seems to me that lowering the saddle opens up the hip angle. what am i getting wrong here?

That's a great drawing, BUT, Dan doesn't measure the actual thigh torso angle, he measures the angle of the torso to a line drawn between the center of the BB and the head of the greater trochanter as a proxy for the thigh-torso angle. Now, that's all well and good for a proper seat hight (consistent knee angle), but if the seat is too low, Dan's angle measurement will indicate a larger angle than the actual thigh-torso angle would be.

Think of it this way, for a given orientation of the "torso line", if the seat is too low or too high, the angle that Dan measures will be the same as for a proper seat hight position. However, the thigh-torso angle will be different for each of those conditions, with the "too low" seat position being more acute. That's what I was getting at...

http://bikeblather.blogspot.com/
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Re: Slowman says Jens' seat is too high... [lacticacid] [ In reply to ]
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The nose of his saddle is almost certainly < 5cm behind the bb (look at the vertical bar on the positioning bike - the forward edge of it appears to run right through the center of the bb, and his saddle is certainly in front of that; also, look at his bike in the background, there's no way to be 5cm back in the forward saddle position on a P3), and, in his stretched out position the ends of his aero extensions are > 75 cm from the tip of his saddle.
Last edited by: jhendric: May 20, 07 10:20
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Re: Slowman says Jens' seat is too high... [lacticacid] [ In reply to ]
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In Reply To:
Why are both positions non-uci legal? I can't see his seat nose to see its relationship to bb and the angles of his arms look like they would be ok.
Well...believe it or not, but the bar extension distance for the FIST position is STILL beyond the UCI rule. Jens is going to need to experiment with angling the bars up or down to get them into compliance.

http://bikeblather.blogspot.com/
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Re: Slowman says Jens' seat is too high... [jhendric] [ In reply to ]
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In Reply To:
The nose of his saddle is almost certainly < 5cm behind the bb (look at the vertical bar on the positioning bike - the forward edge of it appears to run right through the center of the bb, and his saddle is certainly in front of that; also, look at his bike in the background, there's no way to be 5cm back in the forward saddle position on a P3), and, in his stretched out position the ends of his aero extensions are > 75 cm from the tip of his saddle.

The front edge of that vertical bar doesn't run through the center of the BB. The BB shell is attached to the front edge of that bar and thus the center of the BB is offset by half the shell diameter in front of it.

Even so, I don't recall exactly, but the nose of that saddle is pretty short and Jens is pretty far forward. I can't remember if it's UCI legal or not, but I'm pretty sure it's close (within ~1 cm or so). Jens?

http://bikeblather.blogspot.com/
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