If I might say so, that's not Dan's reasoning (nor mine or most anyone else). The reasoning is that, to get your shoulders low on a slack-angled road bike (to be aero), you end up with your knees in your chest. You can't breathe very well, you can restrict circulation through your lower torso/leg region, and the acute thigh-torso angle is generally not thought to be optimal for muscle activation.

The forward position simply helps to keep the upper and lower body in a sensible angle for maximal power. Besides the TT, what part of cycling requires the highest power output? Climbing, right? What do people do when climbing hard? They sit up straight and open the torso-thigh angle.

Conversely, what is the most relaxed part of cycling? Sitting in a bunch, cruising along, right? What do people do when they want to expend the least amount of energy going down the road? They sit up straight and open the thigh-torso angle.

In other words, the forward position is not to "recruit hams and glutes", it's to allow you to ride the way you normally do when riding relaxed and/or powerfully on your road bike. With a nice, open thigh-torso angle. In road cycling, you can do this when drafting or when riding solo -- but slowly -- on a climb. In triathlon, you're riding alone the whole time. To be (1) aero, (2) powerful and (3) relaxed, many people find they like an open thigh-torso angle, and that requires a forward seat position.

I don't try to recruit different muscles when on my tri bike -- just the same ones I use on the road bike, while also riding with my shoulders six inches lower. If I ride with my shoulders that low on my road bike, I can't breathe, I can't generate any power, and my back cramps up. I can do it for a few minutes to catch back up to the bunch on the Saturday roadie ride, but I can't do it for 2-1/2 to 6 hours in a triathlon.

addendum:

Yes, you have it right. Muscle recruitment does not (and should not) change. It's simply to rotate the whole shebang forward around the BB so that your shoulders are low. That's all.

I'll throw in a little info about the "Slam" position for you. We started using it because a lot of riders were always wanting further back on there bikes under bigger loads [hills]. I took several riders to the wind tunnel to see how bad this was and it turns out that the Slam set up is always equal to or better than a steep setup as far as aero. Being real low in the front end is not that important and most people set their bars to low when trying a rearward seat angle. A very key part of making a slack angle work is having good hip or pelvic rotation. If you can't get this rotation done then you want be making much power in a slack setup [no breathing]. We are using "Trigger Point Balls" to help solve trunk tightness [psoas muscles] along with over tightened lower calf muscles which limit Dorsal Flexure. When you flex your foot up toward your knee you will feel a bunch of tightness right below your calf, that will need working on. The choice of seat angle can depend on several things, if your upper leg length is longer then a slack angle may work real well. Back flexibility is a big issue but trunk muscle imbalance is the limiting factor.

John, welcome back. I hope you say around for awhile.

I wish the slam position worked for me but with my shorter upper leg it doesn't seem to. It works great for my wife. She has long legs, upper longer than lower. After extensive experimentation she's just as fast slammed on her road bike as steep on P2k.

I am curious though, do you have a formula or approximate sugggestion as to how high/low a rider should set his handlebars/aerobars when using the "big slam" position. You used to have some photos on your site. I hope you can get them back up some time.

John,

Yes, that was my understanding of your use of the Slam position. By "shoulders low" I mean lower either by dropping in front or by dropping back and down. To cut wind resistance, we've got to do one or the other to be smaller. My limiting factor is quite clearly an inability to feel good when back and down. I started doing both TTs and climbs faster once I moved up forward and opened up my hips.

I also don't have my bars very low because I have a rounded back, and it doesn't get any lower after a point. I can keep moving forward and lowering the bars, but the high point on my back stays just as high. The Slam position could help me get lower, but I just can't (or won't learn to?) ride like that.

Frankly, most of us don't put out the kind of torque where we need to slide back on the seat to get leverage. I recall Greg Lemond's position back in his heyday. On tough climbs, his butt was practically dragging on the rear tire. In triathlon riding, we're producing quite modest wattages on mostly flat courses.

If I might say so, that's not Dan's reasoning (nor mine or most anyone else). The reasoning is that, to get your shoulders low on a slack-angled road bike (to be aero), you end up with your knees in your chest. You can't breathe very well, you can restrict circulation through your lower torso/leg region, and the acute thigh-torso angle is generally not thought to be optimal for muscle activation.

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Julian, perhaps you should read Dan's article "What science says of seat angles" (http://www.slowtwitch.com/...chctr/seatangle.html) since it is exactly what he says - in fact it was a near-direct quote of a quote that he uses. Other sample quotes are "It seems that both authors feel that steep seat angles might distribute work over a greater range of the pedal stroke and in so doing lessen the peak torque that must be applied if should that power application be concentrated over a shorter arc" and "these tests only measured the physiological responses to the biomechanical change generated by a steeper seat angle. As this test was performed in a lab on stationary equipment, the aerodynamic benefit one derives from the ability to achieve a lower frontal profile with a steeper seat angle was not part of the equation". That is, he specifically discusses physiological changes, not trying to obtain an aerodynamic position.

So, my question still stands. John Cobb's slam position accords with my muscular feedback, but again seems to conflict with Dan's opinions. I also think its better not to bring climbing positions into the argument. Firstly, these positions are normally used at low cadence, and secondly I think there may be some important effect from the change in centre of gravity on a steep slope (for instance, Pete Keen and Chris Boardman found that top climbers 'hang' off their handlebars - try this on the flat). On the other hand, Cobb's 'pelvic rotation' seems more crucial (as may be different utilisation of the upper body?).

duncan

Hi John, I've known about your slam position for some time, but thanks for the extra info about core and calves. The first time I saw you write about 'pelvic rotation' I couldn't work out what you meant - until I rode my road bike hard, and found that I do it naturally! And no worries about the calves, I've been using mine in my pedal stroke so long I don't have the tightness you mention. Anyway, I will be giving the slam thing a go for triathlon. Considering I'm not a large rider (5'11" but only 144 Ib), have a short upper body and particularly long lower legs (and the research that shows that steep is better for running off the bike), I thought I would try steep first, but maybe something more laidback will better suit my pedalling style.

duncan

"Julian, perhaps you should read Dan's article 'What science says of seat angles,' since it is exactly what he says."

i don't think i said what you said i said. where did i say that?

of course, i might've writtten an article in which i quoted what other people were saying, but i don't believe i wrote that i believed that. did i? maybe i did. but i don't think i did.

any help out there for a guy with a bad memory? what did i say?

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Dan Empfield
aka Slowman

"seems to conflict with Dan's opinions"

Now that would be a first!

Seriously, I'm convinced you have to experiment and see what works best for YOU. The various theories, measurements, etc. are good starting points but in the end YOU have to go with what works best and feels most comfortable to YOU.

Ok, maybe I exaggerated somewhat - Julian quote of my initial posting has a phrase that I quoted from a quote that you included in your article, and I had assumed that you used that quote to illustrate your ideas about why steep seat angles are better physiologically... Which (after your comments about Macca) you do still think, right?

Nothing conclusive here, of course. "feel" and "might" are not part of the "conclusions" section of the scientific method, last time I checked.

However, I think parts of the quotes that you quote say what I am saying. What I am saying is that cyclists have long demonstrated a self-selected preference for an open thigh-torso angle. Whatever the physiological reasoning behind it -- it is what it is, and has been evident in the peloton for a long, long time. Even among the "sit back and grind when climbing" crowd, they try to get their torsos as upright as the bike will allow.

ipso facto, if you want to ride with a low front end, you have to be steep (the Empfield position).

Now, Cobb correctly reminds us that a low front end is not the only way to be aero -- one can lower the whole body by sitting back and down. Yet, he is wise enough to acknowledge the limitations to this approach -- some people can't handle it due to flexibility or morphological issues. An advantage to the Slam is that it can allow some cyclists to feel that they can exert more force. Those with a self-selected low-cadence, high force pedaling style might prefer the Slam, IF they are flexible enough to handle it.

I am a weak-legged, inflexible cyclist that prefers cadence over force, so I like being forward.