MrIndy

I noticed an interesting effect this week on the trainer. I was riding at a steady state pace of around 151bpm and 90rpm. Then I straightened up my lower back and while maintaining the same rpm and power, noticed my HR decrease by 5bpm to 146bpm. I rounded my back to the original posture and HR went back up. Tried the same thing again the next training session so it seems this effect is totally repeatable. I'm wondering if this is a well known thing or just my own quirk. I'm also curious about the reason for reduced HR. Does straightening the back give the legs better leverage so they are more mechanically efficient, or does it somehow reduce restriction on bloodflow and let the heart work easier. Any thoughts?

2manybikes

Changing the angle of your chest to your thigh changes how strong you are, or the effort required.
If what you did closed the angle a little I'm guessing that's what happened. It became easier. The legs may have more power around the middle of the travel stroke, than at either end.

spoke50

I've noticed this on my recumbent trainer. I can move my hands to the upward position and maintain the cadance much easier than holding my hands down by my side. I figured that the upright position opens up your air flow and doesn't restrict the blood flow as bad. If this is true then you would think that it would make more sense to ride resting on the hoods verses in the drops.

fordfasterr

I broke in a new build on this weekends crit race, the major difference was the steerer tube hieght was MUCH taller than my old bike...

I noticed that I was able to push down with less effort when in the hoods than in the drops.


Strange.


OLD BIKE POSITION:



NEW BIKE POSITION:

late

You want lower for the aerodynamics. Everything else about lower sucks.

Raise Dat Stem!

by Bob Gordon

A flat back is one of the hallmarks of an experienced cyclist, particularly a racer, and over the years I have seen the prevailing attitudes towards rider positioning devolve to the point where if you don't cycle with your back parallel to the ground, you're cast off as a beginner.

But like many other concepts recreational riders adopt, the low back originated in the professional ranks after extensive research in aerodynamics proved this would help the fast go faster. Competitive athletes routinely sacrifice both their short and long term health for the express purpose of winning, but you may have a different agenda.

Lower back disc problems peak the ages of 30 and 50. There are many causes, but if your back pain is exacerbated by riding, it's a good bet the cause is bouncing around on your bike while your lower spine is extensively flexed (loss of lower back arch). A low, forward torso causes the inner portion of the disc (the nucleus purposes) to press back against the outer restraining fibers (the annulus fibroses). This pressure eventually causes the disc to bulge or herniate. The nearby nerves get squeezed, and the next thing you know, someone like me is telling you you have sciatica.

Cycling mitigates some of the problems of a habitually flexed lumbar spine because of the "bridge effect" that's created by resting some of your weight on your hands. But the lumbar region and its soft tissues are still at risk just by being continuously hyper flexed, and if you sit all day at your job, the danger is compounded.

On the flip side, cycling entirely upright does not solve the problem either. True, the inter-vertebral discs and spinal ligaments are in a more neutral position and absorb shock better, but the load is now transmitted axially, which is fatiguing and jarring. Also, in a bolt-upright position you can't use your gluteus or hamstrings to great advantage, which means your thighs (quadriceps) get overworked, you lose a lot of power, the unused hamstrings and gluteal muscles go flabby, and you catch all that wind. It's hard to be happy about all that, racer or no.

There is, however, a position that allows good performance while minimizing risk of lower back injury. I like a stem height and length that puts your back about 50 degrees from horizontal, while your arms and legs bend slightly at the elbows, as shown in figure 2 up there. To achieve this, you'll probably have to raise your bars, and assuming you want to keep the same bar style (as opposed to riding with stingray bars or something), that usually means getting another stem, one with a taller quill or a steep rise to it. If you hit the sweet spot, a photo of you from the side will reveal a nice pyramid composed of top tube, torso and arms.'

...it's funny, bikes used to be such sensible things. Now we are rediscovering sanity and calling it plush. Ahh, progress.

MrIndy

I see what you're saying but my chest is about the same angle to thighs in both changes. What changes is the angle of the pelvis. It's sitting more upright with a hunched lower back, and is more angled toward the bars with a straightened lower back. Maybe this helps to activate the glutes and/or the hamstrings so that load is more efficiently spread across more muscle mass?

Creakyknees

Steve Hogg is one of the fit guru's over at cyclingnews.com, you should read his stuff. He points out that "postural" muscles use up the majority of energy, even when doing intense cycling. So it makes sense that a position that stresses the postural muscles less, will be more economical.

https://www.cyclingnews.com/fitness.p.../bike_position

127.0.0.1

it works indoors only


in the wind you have to be as aero as possible.

2manybikes

I said chest, but it's really the angle of what connects to the leg muscles, twisting the pelvis forward is the mental image I had, but your description is better than mine.

Carbonfiberboy 

You're absolutely correct. I noticed that many years ago. I call it opening your chest. You can do it in full aero tuck or on a comfort bike. Look at photos of the pros. A lot of them will have a totally flat back. But it depends on your flexibility. Lance always has a somewhat rounded back. Works for him. Flat back doesn't mean horizontal. Just flat.

MrIndy

It's amazing how significant the impact is of making such a small postural change. That's about 1/2 a HR zone. I guess that's one thing I've gained by riding riding indoors. I never would have noticed if I wasn't bored out my mind and starting at the cadence and HR numbers.

FreddyBoy

Dude, I would give PCad's left nut to have that sleek a riding position. Either old or new. Looks excellent

cyclehen

"Opening" your chest allows for a greater volume of air to be inspired -- heart rate comes down as more O2 is available.

Garfield Cat

The flat back allows the diaphragm to relax, allowing more air to enter lungs. A curved or hunched back restricts the diaphragm.