A stupid question about heart rates...

rpaul

Hiya,
I'm a bit puzzled. I swapped an MTB for a road bike (CX on slicks) last week and noticed that my heart rate has gone up quite significantly.
Why I am puzzled...
I've been riding 100+ miles a week, every week, for a few years. Plus touring with gear two or three times a year; as per this Monday I've done about 3100 miles since Xmas. My morning commute is 20 miles with 500m gain/loss, and I am generally quite comfortable with it.
So I've swapped for the CX. I didn't use granny gears on the MTB anyway, so the gearing is quite comfortable, I am enjoying myself and all that. I am also going considerably faster (by 15-20% - still too little data to be more precise, I've only done 140 miles on the new bike), as could only be expected, and it doesn't feel like I am pushing any harder than I used to. The cadence is the same. The routes are the same. I am generally just plodding along at a comfy pace.

Why has my heart rate, measured with a chest strap (all kit the same as before) gone up from about 135-140 average to above 160? I thought the heart rate depended on, in plain terms, the amount of effort one applied? Am I missing something?

Thanks.

JackPozzi

How's your position on the cross bike compared to the MTB? I found that just being lower at the front end gives me some variation in HR compared to being sat upright which would account for some (if not all) of the difference?

rpaul

JackPozzi wrote:

How's your position on the cross bike compared to the MTB? I found that just being lower at the front end gives me some variation in HR compared to being sat upright which would account for some (if not all) of the difference?

It is lower, that's true, although not by an awful lot - I used to ride mostly with my hands on bar ends, so similar to the hoods, and stretched horizontally. Could be it partly, although probably not such an increase as a whole. This morning's 20-miler (1h 18 mins) was at 161 bpm average instead of the usual below-140.

I was thinking it could be something along the lines of that moving my ar*e from A to B means still the same mass moved by the same distance, so if I want to do it quicker, it should take more energy... Don't know.

meanredspider

My HR goes up the higher I sit (higher if I stand). I suggest you're pushing harder. There may be a little bit related to a different bike geometry using different (untrained) muscles too (I notice this a little bit when I swap from my ice commuter (MTB on spikers) to my road bike.