iSport on a Mt. Bike

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iSport on a Mt. Bike

Postby jazclrint » Wed Apr 14, 2010 3:25 pm

Hey, has anyone setup their iSport for Mt. biking? I am getting ready to mount mine up to my Mt. Bike and wanted to change the Crr, but can't find to change it. Are there any other threads on here that are useful?
Thank,
Rich
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Re: iSport on a Mt. Bike

Postby Velocomp » Wed Apr 14, 2010 4:26 pm

Go to the racer (RACR) sequence. In there you will find a place to adjust Crr (EST FRIC). The default value of Fric (Crr) is 55 (0.0055). On dirt roads it should be more like 70 (0.007).
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Re: iSport on a Mt. Bike

Postby jazclrint » Wed Apr 14, 2010 9:24 pm

Ahhh. [light bulb goes on] Thank you for the translation! Is there a guide somewhere to what all of the screens mean? [edit]

Based on another thread I am going to go with .016 when I won't be on dirt roads but muddy single track. It's not going to be dead accurate I know, but enough to give me an idea of what's going on.

Thanks again,
Rich
'98 ProFlex 5500c under construction
'13 Schwinn Fastback custom build
'05 Bianchi Axis custom build
'13 Reline Metro Sport custom build
'15 GT Sensor Carbon Pro custom build
'?? A bike who's existence shall not be acknowledged
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Re: iSport on a Mt. Bike

Postby jazclrint » Fri Apr 16, 2010 11:16 pm

Went out on my first Mt. Bike ride with the iSport today:

http://www.mapmyride.com/run//me/orono/ ... 6569872665
http://www.mapmyride.com/view_workout?w ... 6569835684

It seemed to work well. It was funny riding on the road to the trailhead and seeing big wattage numbers, but that was to be expected. Now, the trails I road on are relatively flat, as in no long climbs, only short ones (304 ft of climbing in the 4.5ish miles of trail riding). With that in mind my average wattage was 128 over 45 minutes vs 146 on a road ride the other night (56 minute). Now I know I was working a lot harder (even though I was trying not too), but it was in short bursts on very technical trails. Does this sound about right? The only thing that really throws me off is the calorie counter. It said 310, where MapMyRide.com estimated 637 for a general Mt. Bike ride. I believe MMR's calorie burn numbers. Is this a sign of a problem with setup, or just the difference of Mt. biking being more physical in ways the iSport can't measuer? And, if you have a heart rate monitor, does your heart rate factor into the calories burned to get more accurate reading?

Thanks,
Rich
'98 ProFlex 5500c under construction
'13 Schwinn Fastback custom build
'05 Bianchi Axis custom build
'13 Reline Metro Sport custom build
'15 GT Sensor Carbon Pro custom build
'?? A bike who's existence shall not be acknowledged
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Re: iSport on a Mt. Bike

Postby NCH1 » Fri Apr 16, 2010 11:50 pm

The ibike is determining the kilo-calories of energy you expended to produce the power you are putting to the pedals. One watt of mechanical power is equivalent to 4.3 kilo-calories-I'm sure there is a wiki somewhere on this. This (ibike's) calculation for calories burned is more accurate than one based on: age, weight, height and distance. Though it would be nice to think that 637 calories were burned, given your relatively low sustained power output for the duration of the rides, 310 calories is most likely to be the figure.

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Re: iSport on a Mt. Bike

Postby jazclrint » Mon Apr 19, 2010 9:41 pm

The key there is power to the pedals. These were very technical trails and I was putting out a lot of short hard efforts, which given the poor shape I'm in, caused much higher sustained heart rates. Not to mention the all body workout I got from muscling the bike around and moving around to keep my balance. I had done a road ride the day before at an average of 140w and was not working anywhere near as hard. MMR's estimate calories burned is different for road and MTB given the same distance for this reason. I am sure only 310 calories were burned by the actual pedaling part, but I assure you I worked a lot harder than that over all. I was simply curious if the iSport took heart rate into consideration when calorie counting, as I have yet to receive my heart rate monitor.
'98 ProFlex 5500c under construction
'13 Schwinn Fastback custom build
'05 Bianchi Axis custom build
'13 Reline Metro Sport custom build
'15 GT Sensor Carbon Pro custom build
'?? A bike who's existence shall not be acknowledged
jazclrint
 
Posts: 153
Joined: Thu Feb 25, 2010 9:05 pm

Re: iSport on a Mt. Bike

Postby NCH1 » Mon Apr 19, 2010 10:57 pm

The ibike, as with all other good power meters does not calculate kilo-calories based on heart rate. Heart rate is too variable. This variability may have resulted from a lack of sleep, poor nutrition and diet or fatigue from the previous days workout-amongst others-rather than an indicator of the specific workout currently undertaken. You will find that many coaches have progressed away from the use of heart rate monitors as the sole basis for training. Resting heart rate, that is tested when you awake, may be useful though in determining whether you should undertake the day's training schedule. I am not an exercise physiologist, so I cannot undertake a full explanation of the science.

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