On every post I see ‘check out my position’ a lot of comments revolve around move your stem/seat so that your arms are vertical. Or you get comments like move the spacers to get lower. Well why cant you have your arms stretched out? With them stretched out your are starting to aproach a ‘superman’ position which has been proved by Obree and others to be more aerodynamic.
With the lower the bars comments surely the person who is being e-fitted should be asked what distance events they are going to be doing. If they are being to advised to lower thier position and they are doing 1ronman or longer distances then you could be causing seriuos comfort problems to kneck and back. Any thoughts?
The 90deg arm angle is devised such that your skeletal structure, rather than muscles hold you up. The “superman” may be hella aero, but it’s not exactly practical for a road course, nor is it easy on the upper body. The 90deg FIST angle lets you rest the weight of your upper body on your elbows without using a lot of muscles for support, requiring less energy and leaving you fresher for the run.
Removing spacers and dropping cockpit height improve aerodynamcs, but shouldn’t be done at the cost of comfort or power output. Neither being assessable by internet with photographs however, most posters try to get the most aero position possible - with the idea that the indivisual will adjust for comfort and power output.
I will vouch for khai’s response since my back problems dissapeared when I moved to the 90 degree angle. As far as going lower that is a trainable aspect. You can strengthen the muscles in your upper back and neck to get used to the position for a 112 miles. I’m working on it.
I agree with Slowmans 90 degree FIST fitting for tris.
Why 90 deg angle from torso to upper arm? It carries your weight skeletally rather than muscularly. 90 degrees is tangent to the arc of the toso takes when supported at the saddle. Being supported skeletally means you can use those precious watts by other muscles to propel you rather than simply supporting you. It also relaxes your upper body, improving breathing, again, laeding to making you faster!
90 degrees from upper arm to lower arm? so that you rest on the elbow pad without tending to slide off forwards or backwards. Relaxed upper body means you go faster (stopping from sliding off the elbow pads uses actual energy as well as mental energy) If you’re not focussed on the job at hand, you’re going too slowly.
I just got back on my P2K yesterday after several months off it. It was set up with 90 degree angles and maaaaaannnnn was it comfy riding fast onthe bars! Not so fast uphills with 42/21 gearing (combined with skinny legs and not skinny belly) but an internet purchase of new chainring and cluster to give 39/25 should help that very soon.
Go FIST!
I can’t get a 90 degree elbow angle because if I do, I end up hitting my elbows with my knees.
What should I try and change in my position to stop this?
you can move the pads a bit wider.
It SOUNDS like you may need to move forward, to open up your thigh/torso angle up to the magic 90 degree angle.
Moving your elbow pads a bit wider may also help. If your elbows are too close together, you will probably be more aero, but tha’s not necessarily important. By widening your elbow pads, so they are more in line with your shoulders, will give the air somewhere to go (under your chin, between your arms and out beside your legs and between your legs). It will also allow you to breathe more freely, increasing your uptake of oxygen, generating more power and more speed.
I’d think that moving the pads wider would be worse aerodynamically, as the arms would no longer be breaking air for the legs.
As far as comfort on the bars goes, it would seem that for utmost relaxation of your back and triceps, the best thing would be to have your upper arms as close to vertical as your particular morphology would allow. For some, this would mean a torso/upper arm angle that is slightly less than 90 degrees. If you really want your body weight to be supported by your skeletal system onto the pads of your aerobar, why not have your elbows directly under your shoulders, with your pads right underneath your elbows?
I run slightly longer than 90, works for me as long as I keep the elbows out and knees in
.
With your elbows directly below your shoulders, the rotation of your torso, hinged at your saddle, tends to force you to fall off the front of your saddle and you expend energy and focus on constantly driving youself back on the saddle. This feels like you constantly need to push forward with your hands and arms. This is exactly the situation I had with my first tri bike and aero bars. Pain in the ass to ride like that.
Conversely, with the angle beyond 90 deg, you feel like you are falling behind your arms and have to pull yourself forward all the time.
I’m now set up with my upper arm at 90 degrees to my torso and it is sooooo comfortable and relaxing (except for the energy exerted by my legs)
Ones body does not get pulled down directly by gravity. ( well it does apply vertically of course, but due to the relative lack of compressibility of the spine, the fact taht your shoulders are above your hips means that the force of your torso becomes a rotational force, rotating away from vertical. If the force was truly vertical, then the vertical upper arm, regardless of the 90 deg or not, would work. The only time this would work in practice would be if you ride like Bjorn and have a truly flat (horizontal) back with your shoulders horizontally in line with your hips. In this case you would have vertical upper arms AND have 90 degree torso/upper arm angle. If you ride with your shoulders above your hips, then you need to have your arms not vertical but still at the wonderful 90 degrees relative to your torso.
The force applied by your torso is a rotational force, nominally pivoting around your perinium (behind your balls) and therefore, the resistance of that force must be tangential to the rotational force. ie, 90 deg to your torso. Voila, simple eh?
If you really want your body weight to be supported by your skeletal system onto the pads of your aerobar, why not have your elbows directly under your shoulders, with your pads right underneath your elbows?
With the recommended 90/90 angles, they pretty much are.
Assuming a horizontal forearm as a base position, surely 90/90 angles (upper body / upper arm and upper arm/ forearm) are mutually exclusive options? (unless your upper body is horizontal…and most peoples’ aint).
Keep in mind, this site, this forum, and most of the posters are oriented towards long distance. Most people will tell you that comfort plays in increased part in bike fit as the distance increases. There may be some position changes you would make for a 12 mile TT that would sacrifice comfort for power or aero.
With effective seat angles of 73-80 degrees (from horizontal) which most of us ride, and 90 degree angles in your body, your back would be (surprise surprise!)73-80 degrees from vertical, so not horizontal. This then means that your upper arms should not be vertical (to keep 90 degree body angles) and following on from that, your forearms should NOT be horizontal. They would be 73-80 from vertical, to match your back angle.
The only time your upper arms should be vertical would be if your back is horizontal. This would be achieved with an effective seat angle of 90 degrees or if you reduce your torso/leg angle to less than 90 degrees.