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Heavy bike + wide tires does make you slower

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Heavy bike + wide tires does make you slower

Old 03-22-16, 05:14 PM
  #76  
fa63
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Sorry, I meant to ask where the "4x" wheel vs. bike weight factor comes from. Is that based on some equation, empirical, etc.?
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Old 03-22-16, 07:08 PM
  #77  
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Originally Posted by fa63 View Post
Sorry, I meant to ask where the "4x" wheel vs. bike weight factor comes from. Is that based on some equation, empirical, etc.?
good point.. I looked around, and found no math on where 4x came from. I found this. it makes a lot of assumptions to simplify the calc, and I don't know if any of them are any accurate or just pulling numbers out of the ass (eg. 100 kg rider? 100J of energy lost to air drag?, etc), but it's more than opinions and speculations, which dominate most of this argument. nevertheless, it does mention people's testaments that lighter wheels make them faster, and it kind of brushes around that by saying that there are other factors at play.
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Old 03-22-16, 08:37 PM
  #78  
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Originally Posted by Doge View Post
This is great equipment test at the beginning of every season we started doing in 2010: https://www.strava.com/segments/3438723

Even if you aren't a racer, doing a segment like this is great for comparisons.

We found slightly lower profile wheels that were also lighter performed better here. That was NOT what the calculations said. They said at 28mph - AERO mattered more. But after several tests on similar roads, we found the lighter wheels took less rider energy at the same power. There is a cost to balancing and controlling - side to side movements on real roads. Lots of things feed into that, but wheels are a major factor.
How were you measuring rider energy? Hopefully not HR.
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Old 03-22-16, 08:41 PM
  #79  
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Originally Posted by gregf83 View Post
How were you measuring rider energy? Hopefully not HR.
HR for energy and power with a PM.
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Old 03-22-16, 09:36 PM
  #80  
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Originally Posted by Doge View Post
HR for energy and power with a PM.
HR is not really a good indication of energy used and is never used for that purpose in a scientific environment. It's too variable and subject to environmental factors, temperature, hydration level etc unrelated to energy use.
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Old 03-22-16, 09:46 PM
  #81  
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I've pretty much heard that the decades I've been using it. Works great and is repeatable for us. Better than a wind tunnel and make believe road conditions. Sure - those are repeatable, just they skip the hard stuff.

Your variables are not so variable when repeated tests withing an hour, same temperature, same road - smae power.

I've posted the graphs and video before - I assume you saw those.

BTW - how is energy measured if not a HR monitor?

Last edited by Doge; 03-22-16 at 10:04 PM.
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Old 03-23-16, 08:15 AM
  #82  
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Well, keep working your heavier bike, and you should see your times on your lighter bike improve. Riding my 32+ pound (unloaded) commuter has definitely helped build up some muscles and my avg speeds on my carbon bike have gone up.
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Old 03-23-16, 08:55 AM
  #83  
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Originally Posted by gregf83 View Post
HR is not really a good indication of energy used and is never used for that purpose in a scientific environment. It's too variable and subject to environmental factors, temperature, hydration level etc unrelated to energy use.
I thought I'd go into this more as while I certainly agree the HR on Tues may mean nothing compared with the HR on Wed, how we are using it, it is a good control for testing equipment.

We have a course/track we use. The rider uses the same line and position. We do laps and switch equipment every lap and back again. Typically each setup is tested 3 times. Sometimes 2 times. Most controls are for that day only, so a 165BPM on Monday means nothing for the next test. The rider is warm by the time they get to the test and is never near their personal fatigue point. The biggest variable is wind, which I guess. If it changes much, the test is ruined and we try another day. The 4th test was like this in the video. But as I had my camera I just went with it.

We measure:
-Power - using a Power Tap (we have others). This is most precise and the accuracy is not important as we are measuring lap to lap with the same device. We have the rider hold a set power for the ride.
-HR - pretty much the same setup at 250W equals the same HR for a given day. We can do a run at 11:00, repeat at 12:00 and same HR and power.
-Course / distance - the course is fixed. It is about 3 miles a lap
-Speed AVE - We just record it
-Time / lap - This is what we use to determine the better equipment. It is just a finer measurement than speed.

My conclusion is the lower the time, the better the setup. I don't always know why, but lighter but aero does better than heavier and more aero.

So over about 7 years we use this course, this basic procedure.
As far as variables, HR has changed the least as the rider has doubled in size speed and power are significantly different.

Last edited by Doge; 03-23-16 at 08:59 AM.
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Old 03-23-16, 09:53 AM
  #84  
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I'm just glad that, since I am not a racer, I never really care how fast I am going. I don't know how uch my bike weighs and I really don't care.
It's not that i don't get the folks who do care. I get it ibut, at 55 years old, those things don't matter to me anymore.

I once had a 1998 Raleigh M50 mtb that seemed a lot slower than my road bike but I never thought much about it since I got for short around town rides. I miss that bike even though it was a tank.
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Old 03-23-16, 10:16 AM
  #85  
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I realized commuting with a backpack on my road bike w/ 28mm tires vs my cross bike w/ 35s and panniers that I am back to flying through traffic circles much faster than cars vs barely keeping up with them. That is much more fun.

Also, my max speed is ~8mph higher and my avg is 2-3 mph higher.

My commute time however is identical, 31 minutes each way.

Last edited by HardyWeinberg; 03-23-16 at 10:22 AM.
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Old 03-23-16, 03:12 PM
  #86  
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Originally Posted by Doge View Post
I thought I'd go into this more as while I certainly agree the HR on Tues may mean nothing compared with the HR on Wed, how we are using it, it is a good control for testing equipment.

We have a course/track we use. The rider uses the same line and position. We do laps and switch equipment every lap and back again. Typically each setup is tested 3 times. Sometimes 2 times. Most controls are for that day only, so a 165BPM on Monday means nothing for the next test. The rider is warm by the time they get to the test and is never near their personal fatigue point. The biggest variable is wind, which I guess. If it changes much, the test is ruined and we try another day. The 4th test was like this in the video. But as I had my camera I just went with it.

We measure:
-Power - using a Power Tap (we have others). This is most precise and the accuracy is not important as we are measuring lap to lap with the same device. We have the rider hold a set power for the ride.
-HR - pretty much the same setup at 250W equals the same HR for a given day. We can do a run at 11:00, repeat at 12:00 and same HR and power.
-Course / distance - the course is fixed. It is about 3 miles a lap
-Speed AVE - We just record it
-Time / lap - This is what we use to determine the better equipment. It is just a finer measurement than speed.

My conclusion is the lower the time, the better the setup. I don't always know why, but lighter but aero does better than heavier and more aero.

So over about 7 years we use this course, this basic procedure.
As far as variables, HR has changed the least as the rider has doubled in size speed and power are significantly different.
My comments on the test as presented in the video:
1. Different tires with different Crr
2. Rider sometimes in drops sometimes on hoods
3. Cadence changed. Not really important if you're just comparing speed but becomes a factor if you're looking at HR
4. M5 tested faster on one run and slower on the other so assuming wind was changing? Hard to tell which was the faster wheel/tire combo.

Not sure what conclusions you drew from the tests but I suspect the error bars are larger than any difference measured.

Normal procedure for measuring energy input is O2 consumption.

My recommendation would be to use Chung's Aerolab software and run these tests just after sunrise when wind is less likely to be a factor. Basic test protocol looks fine although I would weight the avg speed more than HR comparisons.
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Old 03-23-16, 03:28 PM
  #87  
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Definitely. A heavy bike + wide tires does make you shower. It makes me shower about twice as much!
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Old 03-23-16, 03:36 PM
  #88  
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-Tires were part of the test as those wheels as they were, were the options. I wanted equal % air (don't know the word) deformation for a 23 and 25. So the thinner tires was filled to (thick cross sectional area) / (thin cross sectional area) * PSI in big tire.

-Rider went/changed position at same sport each time

-Cadence was not controlled as he was holding to power. I'm not thinking it changed, but I was not looking. This may affect movement.

-4th run was too windy. We threw it out. Did it a different time - no video. Had similar results lap to lap but different on overall day and speed HR etc.

VO2 on the road is difficult. In the lab it is not repeatable maybe due to beet root, weird breathing . I turned down the next free VO2 test and we decided not to bother as it was not telling us anything. There is not that much to test in the lab re actually moving efficiency.
I do pickup effort from SP02 dropping, but that is all >AT stuff. I can't find anything better than HR for on the road testing. Lactic acid tester (I have the InsightXC2) may end up helping, but that also at >AT levels.
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Old 03-24-16, 02:01 PM
  #89  
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Some people can push the big rubber very fast...



He actually won his triathlon with that setup!
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