General Discussion Triathlon Talk » Height & Weight Ratio Rss Feed  
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2015-01-08 9:16 PM


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Subject: Height & Weight Ratio
Myself and 3 others use the computrainer for indoor training at the same time.
What i find happening is i am faster than 1 of the riders outside but on the indoor trainer he is much more powerful than I and finishes what ever route we do much quicker than I. According to the software he will be 10 km ahead.
I am trying to work out why.
Many factors played into my head such as the break pads on my rear wheel may be rubbing or the resistance of the trainer is too much

I am the lightest and shortest in the group. could it be that they are producing more power due to the body weight, but outdoors its harder for them? All due to carrying the weight?


2015-01-08 9:53 PM
in reply to: casebusy

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Subject: RE: Height & Weight Ratio

What is meant by "software"?

The speed is determined by how hard someone is going vs the resistance that they have to overcome. Outdoors, this is all over the place depending on conditions, rider size, rider position, gear, etc. Indoors there is only the resistance unit. For most trainers the resistance is a fixed curve. So if riders are of similar ability outside, the one with a larger outdoor resistance generates more power. Since resistance is now equal when indoors, the more powerful rider will go faster.

2015-01-08 10:32 PM
in reply to: casebusy

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Subject: RE: Height & Weight Ratio
Could it be that outdoors you are riding on a hilly course? I'm a lightweight myself and often find that I can keep up with or pass heavier riders, especially guys, on a hilly course, due to a higher power to weight ratio (i.e. I have a lot less body mass to haul up the hill), but they will kick my butt on the Computrainer (or a flat road course) due to higher absolute power.
2015-01-08 10:35 PM
in reply to: Hot Runner

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Subject: RE: Height & Weight Ratio
I would guess wind resistance, you are smaller....less drag and you may have a much better position.
2015-01-08 11:04 PM
in reply to: ec1974

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Subject: RE: Height & Weight Ratio
"Brake pads rubbing"...?

You are over thinking this. If you are lighter than your competitor you will benefit on the road since that lower mass will reduce your power requirements. Indoors wind, weight, riding position, etc are all irrelevant. The only thing that matters is how many watts can you put to the pedals and sustain over time. This explains why that sickly looking 5'10" 135 lb guy is crushing the bike course. That is not meant to take anything away from him, just that some people have the perfect build for certain sports. Just like Jockey's don't make good basketball players.
2015-01-08 11:04 PM
in reply to: ec1974

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Subject: RE: Height & Weight Ratio
"Brake pads rubbing"...?

You are over thinking this. If you are lighter than your competitor you will benefit on the road since that lower mass will reduce your power requirements. Indoors wind, weight, riding position, etc are all irrelevant. The only thing that matters is how many watts can you put to the pedals and sustain over time. This explains why that sickly looking 5'10" 135 lb guy is crushing the bike course. That is not meant to take anything away from him, just that some people have the perfect build for certain sports. Just like Jockey's don't make good basketball players.


2015-01-09 5:06 AM
in reply to: casebusy


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Subject: RE: Height & Weight Ratio

As the smallest/lightest, you will in most cases have a significant advantage outdoors compared to indoors, as the limiting factor in most outdoor rides is usually the hills and who is the fastest on them in most rides save for ones that are in totally flat areas. 

 

On the hills, light bodyweight can dramatically offset lower power, which is why some slender lightweight women can often readily outclimb their 200lbs male counterparts who put out tons of power. On the flats, or on an indoor trainer though, it's a different story as it becomes less power:weight issue and more of a power:aerodynamic issue, so the 200lbs male with high power often will go faster than that low-power slender lightweight.

 

The hillier the course, the bigger advantage you get by being light. The flatter the course (and an indoor trainer is dead-flat), the smaller your weight advantage. On an indoor trainer, you essentially take weight out of the equation, so you get all the upside of higher power from your bigger muscles, and none of the downside of having to actually move that weight.

2015-01-09 5:29 AM
in reply to: 0

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Subject: RE: Height & Weight Ratio
Originally posted by casebusy

Myself and 3 others use the computrainer for indoor training at the same time.
What i find happening is i am faster than 1 of the riders outside but on the indoor trainer he is much more powerful than I and finishes what ever route we do much quicker than I. According to the software he will be 10 km ahead.
I am trying to work out why.
Many factors played into my head such as the break pads on my rear wheel may be rubbing or the resistance of the trainer is too much

I am the lightest and shortest in the group. could it be that they are producing more power due to the body weight, but outdoors its harder for them? All due to carrying the weight?



First of all a computrainer does take weight into account if it's set. It will only make a difference on hilly courses, but 10km is a lot. In a 1hr session ? I don't believe it takes height in effect. I would have to check. It does have the ability to change your aero drag but I don't think it uses height to do it automatically.

Are you guys properly calibrating the computrainers through a roll down test ? If not, the numbers don't mean a thing. During a roll down test you speed up to 25mph+ and stop pedalling. It calculates a number that is used for rolling resistance calibration. If this isn't done, your power numbers, and of course your speed, don't make any sense at all.

If you want to get to the bottom of this, look at your watts, his watts, look at the type of course. But first see if you are properly configured and calibrated. A computrainer is actually pretty accurate with real world speed when properly calibrated





Edited by marcag 2015-01-09 5:34 AM
2015-01-11 8:10 PM
in reply to: #5081455

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Subject: RE: Height & Weight Ratio
I had a similar experience a few years back when our LBS got a 4 person CompuTrainer. The first 30 ride we put everyone in as they actually are, flat course and results were very close at the finish. 2nd 30 minutes we left the settings the same but switched to a hilly course. My 6'5" 260+ pound butt got dropped instantly. On the 3rd 30 minutes we entered everyone with my specs, repeated the hilly course and once again had a bunch finish.
2015-01-14 6:24 AM
in reply to: cwpeters


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25
Subject: RE: Height & Weight Ratio
its very strange
I will have to figure something out. 2 months ago my ftp was extremely low, it was 120.
We had an experienced runner to come give us advice on running. He told me that my ftp should be at least 170 or 180
I can keep the the speed of 12.5 to 13 kph on treadmill for 45 minutes. running is my strongest point out of all 3.

it's going to be interesting to see how the rides outside turn out
2015-01-14 6:44 AM
in reply to: casebusy

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Subject: RE: Height & Weight Ratio
I thnk you'll find that your absolute power improves with training. I'm about 115 pounds ( not petite and compact either, but medium tall and skinny, marathoning background) and the bike is the weakest of my three events. When I started, I was getting power numbers like 120 or less. When I last tested it on a computrainer, I averaged 195 for the 20 minute test. That's still not much absolute power compared to a heavyweight guy, but it's a substantial improvement. However, you'll still be at a disadvantage on a flat course compared to equally fit but heavier riders, assuming other things like equipment, position, etc. are equal.


2015-01-14 7:07 AM
in reply to: marcag

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Subject: RE: Height & Weight Ratio
Originally posted by marcag

Originally posted by casebusy

Myself and 3 others use the computrainer for indoor training at the same time.
What i find happening is i am faster than 1 of the riders outside but on the indoor trainer he is much more powerful than I and finishes what ever route we do much quicker than I. According to the software he will be 10 km ahead.
I am trying to work out why.
Many factors played into my head such as the break pads on my rear wheel may be rubbing or the resistance of the trainer is too much

I am the lightest and shortest in the group. could it be that they are producing more power due to the body weight, but outdoors its harder for them? All due to carrying the weight?



First of all a computrainer does take weight into account if it's set. It will only make a difference on hilly courses, but 10km is a lot. In a 1hr session ? I don't believe it takes height in effect. I would have to check. It does have the ability to change your aero drag but I don't think it uses height to do it automatically.

Are you guys properly calibrating the computrainers through a roll down test ? If not, the numbers don't mean a thing. During a roll down test you speed up to 25mph+ and stop pedalling. It calculates a number that is used for rolling resistance calibration. If this isn't done, your power numbers, and of course your speed, don't make any sense at all.

If you want to get to the bottom of this, look at your watts, his watts, look at the type of course. But first see if you are properly configured and calibrated. A computrainer is actually pretty accurate with real world speed when properly calibrated

Having trained for a couple years in a 16 person computrainer lab with athletes of all sizes here are my two cents! As mentioned above, every ride we all would calibrate our particular trainer. We all were entered into the master system with our weight data and that of our bike. One of my teammates who was tiny (but very a very strong lady) would always put out lower watts than me...a 5'10 much heavier girl and decent biker. I knew she was a better biker than me so I asked what was up. That's when the watts/kg was explained to me. It's your watts to your body weight that counts in the real world. Come our first race, the tiny strong one out rode (and swam and ran lol) MANY of the bigger dudes we rode with all winter with much sexier watt numbers. Add in your ability to climb over a bigger/heavier person and bam....you kick asphalt!



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