"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?"

the new position looks far more comfortable.

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I would agree, the elbows sure look different.

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Pasadena Tri Club

Will the elbow pad stay where it is when he sets up his own bike? I would worry about a neuropathy at the elbow.

"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?

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?

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?

how do you know that?

I don't know that. That's why I brought it up for discussion.

"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).

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.

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.

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?

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.

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Dan Empfield
aka Slowman

Thanks for the pics and analysis. Nice use of compatto....one of my favorite road race terms.

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.

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http://bikeblather.blogspot.com/

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?

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http://bikeblather.blogspot.com/

"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.

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Dan Empfield
aka Slowman

Dan,

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

yeah, you're right. not enough coffee in me yet.

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Dan Empfield
aka Slowman

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...

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http://bikeblather.blogspot.com/

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.

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.

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http://bikeblather.blogspot.com/

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?

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http://bikeblather.blogspot.com/

It seems that most would agree that the new position is more comfortable. The current set up on my tri bike is similar, and I feel very comfortable on the aero bars for extended periods of time (2-3 hour rides)

For shorter rides such as a sprint triathlon (less than 1/2 hour) do you really need to optimize comfort, or should you go with a position that is somewhat more aero?

The saddle tip is close to legal -- about 3cm back. I can pretty easily push it to 5cm without changing my position, just by nose-riding a little more.


--jens

to be clear on the issue of saddle height and its relevance to hip angle, the saddle height is tackled first, before anything else (according to the protocol to which i ascribe), rendering the question moot for the purpose of arriving at the appropriate bike fit.

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Dan Empfield
aka Slowman

True...and I fully understand. It's just that when we measured "your angle" for the old and new positions yesterday, we were all somewhat surprised that the difference was only 3 degrees. I'm just saying that the lower seat of the old position would actually make the "thigh-torso" tighter than what your proxy angle would suggest, i.e. the difference was greater.

I'm just bringing this up in the context of the other thread that started this whole thing ;-)

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http://bikeblather.blogspot.com/

Can someone explain to me why his position needed to be changed in the first place. What was the motivation to being changed. I also don't really understand the relationship of the "triathlon" FIST fit with a guy who just does time trials. Why couldn't he have just raised the saddle and left everything else the same?

I thought one of the benefits of a steep angle was the supposed value of saving one's "running legs" as the pattern of muscle recruitment is different. Correct me if I am wrong but I thought Jens didn't do triathlons, so shouldn't a position that optimizes power to drag ratio be the correct position regardless of how one achieves it. Now, I know that Jens has been in a wind tunnel so has his drag numbers down and has a power meter so I am sure he knows his Power/drag ratio for his old position. What is it now? The After position certainly looks at least aesthetically to be less aerodynamic. So how much power did he gain?

It came from the comfort/aero thread a few days back. Search and you should find it. Realistically, what Jens needs, is to find a way around the UCI rules that will be enforced next year. I believe this was Dan trying to help him.

Second, I think part of Dan's argumen is that steep is no longer a tri only thing, i.e. Zabriskie.

See the start of all this, the "aero vs. power" thread from last week:

http://forum.slowtwitch.com/..._reply;so=ASC;mh=25;

Also, one thing I gathered out of watching the fitting session yesterday is that there was absolutely no thought into "saving muscles" for running or anything like that (obviously not meaningful for a TTer). Once the proper seat height was set, the adjustments for the fore-aft position of the seat and the bars was an iterative process that depended on a lot of feedback from Jens about what felt better from a power production standpoint while pedaling with a moderate load being applied by Dan's CT unit (btw, the CT wasn't used in any fashion besides applying a steady load, i.e. erg mode).

It got to the point of making minor adjustments with Dan asking Jens "Does this feel better, worse, or the same?". I even asked Dan at one point if he'd had training as an optomotrist since it sounded like I was watching a lens prescription process ;-)

The whole point was to try to gain back some of the power Jens lost (as compared to his road position) in his aerodynamically optimum position. If he gains 20W of output but only gains 10W of drag, that's a net win for him. Now it's up to Jens to evaluate and/or tweak the position to get his best power/drag ratio.

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http://bikeblather.blogspot.com/

My only comment is that Jens now needs to change his handle to Jens-compatto. The change of name is not something that just anyone can get from Slowman. This is like going to Buckingham Palace and getting Knighted...or as close as you can get on ST. Even Bjorn, after training in Xantusia and winning Wildflower is yet to get this from Slowman.

I don't think going steep has anything to do with saving the running legs really. If you do it properly the whole point is that your body is in the same position just rotated so that you have less frontal area. I know some studies have shown people to run faster "Steep" but I wonder if this is just because they had less drag and therefore spent less time at their power output?

I just had the bike of my life this morning in a triathlon and it was the day after I figured out how to make the aero position feel (to my legs) just like a normal road bike position (i went steeper which opened up my hip angle)....and running sure hasn't ever felt easier in any way no matter what position I was in =)

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Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter

I believe the study you are referring to was conducted indoors on stationary bikes, so drag wasn't a factor.

Was the study comparing steepness of seatposts or openess of hip angle?

Slowman discusses the Garside study here...

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

 Thanks for the link. I thought this item was interesting:

"This particular study simply utilized a seat shifter, a nifty device once in relatively common usage by triathletes in the early '90s. It replaced the bicycle’s seat post, and with a lever on the handlebars you could change your seat angle on the fly. I’ve tracked down the study’s author and emailed him, asking him to verify that no changes were made to the handlebar set-ups as the seat angles were altered during his study. I’ve yet to receive a reply. I don’t, however, see any notation that any change in the bikes was effected other than a change in the seat angle provided by the seat shifter."

Are these seat shifters still available? Might be something worth using for a training ride along with a powermeter to find your optimal angle.

From a 1990 article:

"Steep angled seat tubed bikes will be non-existent, as will LeMondesque shallow angled seat tubed bikes. In fact, seat tube angle will become largely unimportant as riders adopt systems for altering their seat positions and effective seat angles while riding. Virtually everyone will utilize a system such as the brand new Seat Shifter (an American product from San Carlos, California), which allows the rider to choose four different positions of the saddle in relation to the bottom bracket via a small handlebar mounted lever. Riders can set the Seat Shifter to provide their standard/ hill-climbing/ behind the bottom bracket position as the rearward most setting on the seat shifter, thus allowing three forward positions with a total of 4" of travel. When hill climbing, riders can move the saddle back, sit up, and climb in their most effective and efficient position. On a long climb, they can alternate between this position and the next forward position to change muscle group usage and reduce fatigue. On downhills and flats, riders can slide all the way forward and stretch out onto their aero handlebars, gaining a two to three MPH speed increase by dramatically increasing their biomechanical positioning, efficiency, and comfort. Once again, riders can alternate between this forwardmost position and its next closest position to reduce fatigue and enhance recovery. Not only will this type of system make cycling faster, more efficient, and more comfortable, but it will also eliminate almost all cases of lower back fatigue and Shermer/Solon neck."

Another comment from the link:

"The authors only guess at the causes for the enhanced ability to perform with the steeper seat angle, and posit about the,

"greater contribution of the hamstrings and gluteus muscles (Heil et al., 1995). Although muscle recruitment cannot be determined from the present results, alterations in muscle recruitment or activation patterns can have the effect of distributing muscular work over a greater muscle mass (increased contribution of the hamstring and gluteus muscles) that would theoretically reduced the work rate per individual muscle fiber (Coyle et al., 1988).""

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That seems counterintuitive. If you are using the glutes and hams more, wouldn't you expect them to be more fatigued at the end of the ride? How would that help the performance on the run?

The new position sure looks more comfy and "normal". But any discussion is purely academic. The real proof in the pudding is when Jens does a few TT's this way and compares his times to those in his old position. Only then will we know what works best for him.

"Are these seat shifters still available"

M2Racer made a similiar device a few years ago. I experimented with one on my Giant TCR about five years ago. I thought the device had merit, but found it difficult to adjust on the fly and it felt a bit "wobbly", even at my 150 lbs.

Thanks. I found their website.

When you say "wobbly" do you mean only when shifting or during the entire ride?

When I say "wobbly" that means that there seemed to be a lot of flex in the system at all times. I noticed it throughout the ride. The shifting part was difficult because you had to move a lever and then shift your butt forward or backward. Sometimes the saddle just didn't want to co-operate as it would seem to bind a bit on the rails.

As mentioned, I think the unit has some merit, but needs a better design. In the end I just got two seat posts - setback for road and neutral for tri. Ran the TCR much like a Soloist this way.

the problem is that the cda at o yaw meaby faster but in yaw slower
and give away lot power that for better cda that mostly worse idea
at least even pro cyclist do not want to do that ,
you really have to isolate the rider from the bike at several yaw angle
and also measure the power closely to have a good measurement

there is a lot to it
more weight on the front can also mean greater crr of the tyre
as the latest test we did we saw that crr is not linear as you would expect
but making a S curve
well al this depands on tyre construction and road and speed of course

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