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PostPosted: Thu Mar 28, 2013 12:15 pm 
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Location: Adelaide, Australia
Hey guys

I've got a school project coming up (research project for fellow SACE students). Long story short, I'm stuck for ideas and was wondering if there were any aspects of cycling that you guys wanted investigated (ie you don't have the time) and would be cheap (my budget for this is practically nothing) to research and investigate.

if you have ANY ideas, I would be interested to hear them

Thanks

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PostPosted: Thu Mar 28, 2013 2:41 pm 
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Location: Geneva, Switzerland
How about some rolling resistance testing, for various tires and inflation pressures? people keep referring to the same study by J Heine, but he used one rider (I think, maybe 2) and a limited set of tires. You could update the list of tires (eg. the mythical Veloflex/Vredestein latex versus pro4/butyl, etc), test a couple of sizes (23 vs 25 or 28 in the same tire), and a couple pressures (eg 90 vs 110 for 23mm tires?).

You need a straight ramp with no traffic (or better yet, several, with varying surface), no wind, a standard rider position, and a chronometer (or maybe just the max speed recorded on the computer?). Several riders, each would do several reps with the same setup, then change wheels and repeat (ok so you better have everyone on shimano 10 speed so changes are easier). No pedaling, just roll down the hill.


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PostPosted: Fri Mar 29, 2013 4:17 am 
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The effect of mass on climbing times. Use a power meter to control for power. Either attach or not attach 5 kg mass to bottom bracket and compare climbing times at different power outputs, then plot power versus time. Then attach 5 kg mass to body and do the same (for example, attached to belt pouch). Maintain constant power along a relatively steady road. Make sure to weigh rider + bike before and after trial to account for sweat loss. Compare with power-mass equations.

If you don't want to use the bottom bracket use the water bottles (almost as good).

Ideally I'd also want to see the effect of the mass on the rims but that may be harder to work out.

You need a powertap, which can be borrowed.

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PostPosted: Fri Mar 29, 2013 4:37 am 
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Here's another: the effect of crank length on physical performance. This has been done, but here I propose a twist: set each crank independently.

This is interesting because it addresses the question of pedal asymmetry: obviously if the two cranks are different length you won't have a symmetric pedal stroke.

So get two crank lengths: one well-fitting, one much smaller. Or, if you can, get an old crankset and thread a second pedal hole at a small radius. So, for example, 170 mm and 140 mm. Then ride with both at 170, both at 140, or one at each (both ways). Warm up first, then do some physical test. Make sure to repeat each trial to account for ride-to-ride variability. Use multiple test subjects of similar size so they can use the same cranks.

GF proposes trying bikes of similar build but different materials, attach lightning rodes, then sending subjects out into thunder storm. Does the steel frame attract more strikes than carbon fiber? I don't support this suggestion.

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PostPosted: Fri Mar 29, 2013 10:37 am 
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Location: Adelaide, Australia
hey djconnel, basilic, thanks for your input

The rolling resistance test sounds like a hard one to do, so many variables to control... but it sounds relatively cheap to do though, I'll have a think about it

on the cranks topic, I used to use 175mm cranks, but have now dropped to 170mm. There were alot of uncontrolled variables in this test (ie crank weight, chainring size etc.) but I've perceived a few differences in the ride... I would be interested to test that further, but I feel that crank length is a function of personal preference. On the note of different lengths, I know someone who has used different lengths without noticing it (only noticing when he was cleaning his bike). That said, it was 170 and 172.5 so not the most different of sizes... will make an interesting test the 165mm and 175mm...

on the power vs weight ratio, I'll be very interested to try something like that. If I can get a hold of a power tap I'll definitely try it. In adding weight to the rim, would using a heavier tube do that? Or a rim with the same dimensions, with a different weight?

thanks for your input

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PostPosted: Fri Mar 29, 2013 12:36 pm 
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To see a measurable difference with crank length, you need to go big: not 5 mm, like 30 mm. There's too much variability comparing one ride to the next. I've not seen the asymmetry test done, but perhaps it's out there (I didn't do a literature search). There's been a lot of debate about L-R symmetry, so I was trying to think about how to break it without the rider having to intentionally pedal less hard with one foot. Of course it would be best if you could measure L & R power separately, as well, but that would require a power meter which could handle this (Rotor, Vector, Polar). I was proposing two holes in the same crankset, although in retrospect this would add a lot of flex for the outer hole. So perhaps better to use two different cranksets (same model).

For the weight, easiest would just be two water bottles filled with sand, I think. The heavier the better. Then you could move the weight to a running belt to see if weight on the body is worse than on the bike, or vice-versa. And, of course, ride with empty bottles as well, as a control (empty instead of none to keep wind resistance the same).

On rolling resistance: Jan Heine used a Soapbox Derby track, I believe, then did coasting tests from the top. It requires careful modeling to extract Crr from this.

One more: the effect of crank flex on power transmission efficiency. You'd need two otherwise identical cranks, one flexy, one stiff. Camillo could make these, but not sure how easy it will be to get that. Anyway, you'd swap the crank, compare power @ pedal, power @ hub, and performance in some test (like ability to climb a short hill). You'd need multiple subjects, multiple runs.

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PostPosted: Sat Mar 30, 2013 8:26 am 
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you guys are full of great ideas... thanks for your input djconnel. I'll start thinking about good ways to test these and will go for the one that seems easiest to investigate. For the purposes of the task, I think any of these investigations will show good scientific procedure, just depends on which one is easiest.

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PostPosted: Sat Mar 30, 2013 9:20 am 
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How about this, the difference between having an extra kg on the frame vs 500 grams on wheels.


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PostPosted: Wed Apr 10, 2013 8:44 pm 
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How about seat to handlebar drop? At what point do aero gains due to getting lower / flatter become offset by biomechanical inefficiencies. You might even bring in subjective "rate of perceived exertion" vs. power output for the various positions.


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PostPosted: Wed Apr 10, 2013 10:06 pm 
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To stay within budget, don't experiment. Theorize based on published data and established theory. For example, demonstrate that when the bike is stationary but the wheels are turning, as on rollers, the spoke nipples follow elliptical paths, contrary to intuition. Just kidding.

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PostPosted: Wed Apr 10, 2013 10:12 pm 
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Effects of crank length on time taken to reach peak power, and does it change peak power even. Again using djconnels idea of varying size by a great degree. Don't forget to account for the shorter crank length in the seat heigh.

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PostPosted: Thu Apr 11, 2013 4:00 pm 
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djconnel wrote:
The effect of mass on climbing times. Use a power meter to control for power.


why use a powermeter at all when you could just use a motor. seems easier to regulate power output.


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PostPosted: Thu Apr 11, 2013 10:58 pm 
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nathanong87 wrote:
djconnel wrote:
The effect of mass on climbing times. Use a power meter to control for power.


why use a powermeter at all when you could just use a motor. seems easier to regulate power output.


Because one of the arguments made is that "micro-accelerations" enhance the importance of mass. An argument could be made the motor, with its essentially perfectly smooth "pedal stroke", would not be exposed to these.

I don't buy the "micro-acceleration" argument: they're primarily elastic (energy conserving). But it's good to do the experiment.

The mass on the wheel one is a good one, but it's hard to attach a lot of mass to wheels, and you want the additional mass to be large to yield a measurable signal.

A big noise source in power-speed is temperature, which has a strong effect on rolling resistance. So you need to measure temperature. Garmin does this but takes a long time to equilibriate.

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Posted: Thu Apr 11, 2013 10:58 pm 


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PostPosted: Fri Apr 12, 2013 5:32 pm 
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Location: near Seattle
"Cycling Science" by Max Glaskin caught my eye in our small town library yesterday, so I checked it out. It's a coffee table book, with footnotes citing scientific articles. Just from this book, I'm learning that more has been done in this field than I would have guessed.

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