DIY Bike Fit? I know what you’re thinking! Surely it would be better to get a bike fit from a professional? Agreed. However, we are in the midst of the greatest recession since WWII and I’m not exactly flush with cash right now! 😂
Anyway, I enjoy learning about biomechanics and stuff so spending a few weeks teaching myself bike fitting is a good investment in my mind. Also, as I always say…
Don’t let the perfect be the enemy of the good
So DIY Bike Fit it is! I’m going to go through my own DIY Bike Fit in this article in agonizing detail. I’ll tag some of the real bike fitters (whose material I’m learning from) in the post so you guys can find some information that is actually good!
DIY Bike Fit – Ankle Angle
First up is ankle position. As you can see I have a lot to learn! I got these “ideal” numbers from @bikefitadviser so props to John! 🙏
I’m thinking my seat is too high but I’m going to wait to make any changes until I’ve learned a bit more and been through all my joint angles.
Man, I hope my frame is the right size. If I can’t afford a bike fit I definitely can’t afford a new bike!! 😂
Part two of the DIY Bike Fit focusses on the knee and we’ll need to look at the angles in both the 6 o’clock and 12 o’clock positions.
It seems I’m doing a little better here. My knee angle in both positions seems to be within the ideal range. Since my ankle angle was way off, I’m guessing my goal is to fix the ankle angle while maintaining the knee angles.
For the ankle, my foot was inclined toward the ground too much (like when you stand on your tip toes). That made me think my seat was too high. Since the knee angle looks good it may be that the seat needs to come down a bit and drop the heel down a little as long as the knee does pretty much the same thing as it’s doing now.
Looks like I did ok again here.
This one is way more tricky to determine than the knee and ankle. Trying to line up the top line with the best representation on the “line of the spine” is really difficult. I basically just tried to bisect my torso with the line. Leaving as much in front of the line as behind. I’m not sure I got it dead on. The “line of the thigh” is much easier.
Also, determining the position of my hip joint is tricky. This is where a real live bit fit would be way better. You could palpate the greater trochanter and stick a sticker on it. Come to think of it, I could just do that myself! (perhaps I’ll do that for when I’ve made my adjustments and I’m reviewing my bike fit).
Also, I think these “ideal” angles were prescribed more for the upright rider (as opposed to the aero position on the triathlon bike). So I’ll have to look into that.
Another fail! 😂
This one surprised me as I thought I was supposed to be quite “forward” and sitting on top of my elbows. Good job I’ve been doing my homework!
Not sure what this one means yet. I have been thinking my seat is too high (based on ankle angles), but if my seat goes down a bit this shoulder angle will become even smaller, taking me away from the ideal range.
That makes me wonder if I’m sitting too far forward on my seat. Or maybe my seat needs to move back a bit (an adjustment I think may be known as “aft”). Perhaps my elbow pads are too close to my seat (I don’t know what this measurement is called yet).
Anyway, I’ll make note of it and keep going.
Next up…actually, I’m not sure…elbow angle?
I actually couldn’t find any direct references to an “ideal” elbow angle, which suprised me a little. So I went on google images and just found some images of the top 4 finishers at last the Ironman World Championships in 2019.
The elbow angle of the top 4 reflected what I found from just browsing around images of lots of pro triathletes. The elbow angle seems to vary widely. The elbow angle ranged from a low of 79° to a high of 106°. My elbow angle currently sits at 101°. This seems to be a little towards the bigger end of that range.
There is such a large variation in the pros and there doesn’t seem to be much online to guide me in terms of what is “ideal”. So I’m going to assume it’s not terribly important as long as my elbow angle is not extremely unusual.
This makes sense to me for a few reasons. The first is that the forces experienced by the elbow when biking in the aero position are fairly minimal. The elbow bears a static load which is the easiest type of load to tolerate (when compared to slow moving or fast moving). The forces at the elbow are going to be orders of magnitude lower than those experienced at the knee, for example. So the elbow is not going to be a particularly vulnerable joint for a repetitive stress injury.
The elbow just sits in behind the hand and forearm, so it’s unlikely to have a huge impact on aerodynamics.
Finally, the elbow makes minimal (if any) real contribution to force production. Sure, its position will influence the position of the other prime movers (like the hip for example). But your triceps and biceps are just not going to help you put out significantly more power on the bike. As we know, that’s mostly going to come from the quads and glutes.
So I’m going to accept anywhere from 90° to 100° as that would put me in the middle of the range.
After getting myself quite confused by elbow angle yesterday I found myself in a similar position today. There doesn’t seem to be much out there on the “ideal” position for the inclination of the forearm.
Obviously this is going to have a big impact on the angle of the elbow. After doing a little research it would seem that the forearm inclination that the triathlete find most comfortable would be best.
The forearm inclination will influence aerodynamics and power output, however, there is not so much info on an optimal range. Short of getting in a wind tunnel with some experts, it’s probably going to be a case of trial and error.
As we can see in the photos, I’m currently set up with a pretty much horizontal forearm. Similar to the taller and better looking Jan Frodeno. However, Lucy Charles-Barclay seems to be a slightly quicker triathlete than me and she is donning a 23° incline. So it would seem I have some options.
My gut tells me my forearm angle is too flat. I’ve been thinking for months that I feel like I’m sliding forward on the elbow pads and using my hands to brace me. From what I’ve learned, keeping the hands relaxed is important as it correlates with less tension in the shoulders. After about 3 hours on the bike I can barely get my hand behind my back, so less shoulder tension sounds nice!
So I’m thinking I’ll try adding a little inclination in the forearm. I’ll just go off feel at first and then adjust over a few weeks.
- My foot is angled down too much
- My knee is angled correctly
- My hip is angled correctly
- My shoulder angle is too small (my elbow is too far underneath me)
- My elbow angle is probably ok
- My forearm is angled too far down (elbow higher than forearm)
My proposed solution
- Lower the seat a little. This should bring the inclination of the foot up a little and increase the shoulder angle.
- Incline the aero bars upwards a little