More Data From Silca - Tire Pressure & Comfort ( & New Link to part 3B)

Jun 24, 16 5:21

Post #1 of 31 Views: 7036

Another fascinating read about the impact tire pressure has on ride qualities.

https://silca.cc/...pressure-and-comfort

Thank you to all of the people who have been contributing data to these discussions.

Update: More data from Silica......

Via copy and paste.
Part 3B: FAQ and Putting it Together So Far
We've decided to push Part 4 back a week and do an FAQ about the first 3 segments of our series as we have had so many questions and comments regarding the series so far. For a quick recap:
Part1: History of tires getting wider and the effect of rim width on actual tire width
Part2: Measuring Tire Stiffness in the Lab
Part3: How Tire Stiffness effects ride comfort for the entire bicycle

https://silca.cc/...g-it-together-so-far

Last edited by: TRIing2Run: Jul 1, 16 9:52

Re: More Data From Silca - Tire Pressure & Comfort [TRIing2Run] [ In reply to ]

Jun 24, 16 5:33

Post #2 of 31 Views: 7019

Its really so cool that Silica is posting all this data, thank you silica!

2024: Bevoman, Galveston, Alcatraz, Marble Falls, Santa Cruz

Re: More Data From Silca - Tire Pressure & Comfort [TRIing2Run] [ In reply to ]

Jun 24, 16 5:39

Post #3 of 31 Views: 7012

tmm;dr

(Too much math; didn't read)

Pink-ish

Chicago Cubs - 2016 WORLD SERIES Champions!!!!

"If ever the time should come, when vain and aspiring men shall possess the highest seats in government, our country will stand in need of its experienced patriots to prevent its ruin." - Samuel Adams

Re: More Data From Silca - Tire Pressure & Comfort [TRIing2Run] [ In reply to ]

Jun 24, 16 6:30

Post #4 of 31 Views: 6966

Quote:

More interestingly from a SILCA standpoint, is that the difference [in vertical stiffness] between 4 of the 5 frames is less than the gauge error of a standard bicycle pump (+/-5%),

So to some up, we all should be getting more accurate pressure gauges instead of freaking out about frame stiffness - says a pump manufacturer ;-) But they do seem to back it up with real data.

Re: More Data From Silca - Tire Pressure & Comfort [TRIing2Run] [ In reply to ]

Jun 24, 16 7:37

Post #5 of 31 Views: 6900

Good information. But the conclusion ends with, "Triathletes, some of whom are now racing at pressures 2Bar (30psi) lower than before, are telling us that they are running better off the bike as they are less fatigued from vibration, and better still, they aren't riding any slower! "

And, to my knowledge, there isn't any evidence that "vibration" causes the type of physiological fatigue that would affect run performance.

It might. It's plausible. But I don't think we know.

Last edited by: trail: Jun 24, 16 7:39

Re: More Data From Silca - Tire Pressure & Comfort [TRIing2Run] [ In reply to ]

Jun 24, 16 7:52

Post #6 of 31 Views: 6875

I keep trying to explain springs in series to people with regards to comfort. You can clearly deflect a tire with your thumb, but how much can your thumb deflect a frame, that should tell you that tires clearly dominate vertical compliance.

Re: More Data From Silca - Tire Pressure & Comfort [trail] [ In reply to ]

Jun 24, 16 8:06

Post #7 of 31 Views: 6857

Vibration alone may not be fatiguing, but tensing up is. That is my normal reaction when the roads turn into washboards. I had been running 95 psi / 23mm front and 105 psi / 25mm back. With all of the data coming out from Flo, Silca, and Tom, I did a few test workouts at 90 f / 95 r and like the change in the level of vibration on my normal training routs. It also resulted in slightly faster avg. speeds. I used those pressures for my last race and finished the highest overall and highest bike leg place of any of my races to date.

Re: More Data From Silca - Tire Pressure & Comfort [TRIing2Run] [ In reply to ]

Jun 24, 16 13:27

Post #8 of 31 Views: 6767

TRIing2Run wrote:

Vibration alone may not be fatiguing, but tensing up is. That is my normal reaction when the roads turn into washboards. I had been running 95 psi / 23mm front and 105 psi / 25mm back. With all of the data coming out from Flo, Silca, and Tom, I did a few test workouts at 90 f / 95 r and like the change in the level of vibration on my normal training routs. It also resulted in slightly faster avg. speeds. I used those pressures for my last race and finished the highest overall and highest bike leg place of any of my races to date.

Happy to hear that. Science works :)

Chris Thornham
Co-Founder And Previous Owner Of FLO Cycling

Re: More Data From Silca - Tire Pressure & Comfort [Canadian] [ In reply to ]

Jun 24, 16 18:08

Post #9 of 31 Views: 6628

Yes it does. Thanks for all you have shared. My wife love s the 30 we picked up for her road bike. I hope to add a new front 90 to the collection shortly. 😎

Re: More Data From Silca - Tire Pressure & Comfort [TRIing2Run] [ In reply to ]

Jun 25, 16 8:32

Post #10 of 31 Views: 6477

TRIing2Run wrote:

Vibration alone may not be fatiguing, but tensing up is. That is my normal reaction when the roads turn into washboards. I had been running 95 psi / 23mm front and 105 psi / 25mm back. With all of the data coming out from Flo, Silca, and Tom, I did a few test workouts at 90 f / 95 r and like the change in the level of vibration on my normal training routs. It also resulted in slightly faster avg. speeds. I used those pressures for my last race and finished the highest overall and highest bike leg place of any of my races to date.

May I ask how much you weigh? I know I've seen a chart with weight and tire pressures somewhere before but am interested in how things correlate.

I also wonder how my TitanFlex frame would effect this.

Formerly DrD

Re: More Data From Silca - Tire Pressure & Comfort [TRIing2Run] [ In reply to ]

Jun 25, 16 8:45

Post #11 of 31 Views: 6466

The best tire gauge for bikes in case anyone was wondering...

http://www.kappiuscomponents.com/...gital-pressure-gauge

Re: More Data From Silca - Tire Pressure & Comfort [Broken Leg Guy] [ In reply to ]

Jun 25, 16 9:02

Post #12 of 31 Views: 6438

My weight 167lb.
The system is just a series of springs. The system would have more flex with the more flexible frame. Should not be too different, tires would be a slightly lower % of total. Would still get better road grip for cornering.

Last edited by: TRIing2Run: Jun 25, 16 9:09

Re: More Data From Silca - Tire Pressure & Comfort [TRIing2Run] [ In reply to ]

Jun 25, 16 13:56

Post #13 of 31 Views: 6359

I'm curious how much weight plays a roll here. I am 235lbs and totally buy into the lower PSI science, as I've always ridden at max as a result of my weight. Being a heavier guy, I'm curious if there is any info out there suggesting what someone of my size should ride at? The normal charts will all say max.

Re: More Data From Silca - Tire Pressure & Comfort [Silvercivic27] [ In reply to ]

Jun 25, 16 14:33

Post #14 of 31 Views: 6329

Thanks for the heads up on that. I've been looking for a better gauge.

Re: More Data From Silca - Tire Pressure & Comfort [TRIing2Run] [ In reply to ]

Jun 25, 16 14:46

Post #15 of 31 Views: 6316

I'm about 10 lbs heavier than you. I typically ride at 95/100. Combined with the TitanFlex it's a very smooth ride.

Formerly DrD

Re: More Data From Silca - Tire Pressure & Comfort [GreenPlease] [ In reply to ]

Jun 25, 16 18:31

Post #16 of 31 Views: 6255

GreenPlease wrote:

Thanks for the heads up on that. I've been looking for a better gauge.

Although that gage claims it can be used for "bleed down", based on the design of the connection (a Silca "crack pipe") and the button location, I want to point out that it appears the only thing it will bleed air from is the small volume between the gage and the valve.

Once the pressure in that section drops below the pressure inside the tire, a presta valve automatically closes.

http://bikeblather.blogspot.com/

Re: More Data From Silca - Tire Pressure & Comfort [Tom A.] [ In reply to ]

Jun 25, 16 18:36

Post #17 of 31 Views: 6250

Tom A. wrote:

GreenPlease wrote:

Thanks for the heads up on that. I've been looking for a better gauge.

Although that gage claims it can be used for "bleed down", based on the design of the connection (a Silca "crack pipe") and the button location, I want to point out that it appears the only thing it will bleed air from is the small volume between the gage and the valve.

Once the pressure in that section drops below the pressure inside the tire, a presta valve automatically closes.

I would not have thought of that. I wish there was something like my Topeak handheld air pressure gauge (which is great for bleeding and fits disc wheels) that I knew was accurate :/

Re: More Data From Silca - Tire Pressure & Comfort [GreenPlease] [ In reply to ]

Jun 25, 16 19:01

Post #18 of 31 Views: 6226

I will be using a manometer from now on at all races because I do not trust gauges. Physical properties of a liquid cannot lie!

Re: More Data From Silca - Tire Pressure & Comfort [Tom A.] [ In reply to ]

Jun 25, 16 19:03

Post #19 of 31 Views: 6226

That depends. To get the pressure in the first place to measure the tire pressure, the gauge has to depress the valve stem. If that depression is maintained, it could bleed pressure off of the tire.

Re: More Data From Silca - Tire Pressure & Comfort [iank] [ In reply to ]

Jun 25, 16 19:07

Post #20 of 31 Views: 6220

For bike tire pressures, it will need to be quite tall. The other option would be to go really old school and get one filled with mercury.

Last edited by: TRIing2Run: Jun 26, 16 3:12

Re: More Data From Silca - Tire Pressure & Comfort [Tom A.] [ In reply to ]

Jun 25, 16 19:17

Post #21 of 31 Views: 6215

Tom A. wrote:

Although that gage claims it can be used for "bleed down", based on the design of the connection (a Silca "crack pipe") and the button location, I want to point out that it appears the only thing it will bleed air from is the small volume between the gage and the valve.

Once the pressure in that section drops below the pressure inside the tire, a presta valve automatically closes.

Tom, I think it has to press down the presta valve as it screws on, how else would it ever even read the pressure?

Re: More Data From Silca - Tire Pressure & Comfort [TRIing2Run] [ In reply to ]

Jun 25, 16 19:32

Post #22 of 31 Views: 6211

TRIing2Run wrote:

That depends. To get the pressure in the first place to measure the tire pressure, the gauge has to depress the valve stem. If that depression is maintained, it could bleed pressure off of the tire.

From what I understand about how the Silca adapter operates, I don't think it physically depresses the presta valve...so, I guess I'm not sure then how that Kappius gage actually functions...hmmm.

Yeah, if the connection physically depresses the valve, the bleed should work...but then, I guess I'd be concerned about how much pressureis lost when the gage is removed.

I guess I still prefer a "known accuracy" gage attached to the pump, since you can then "sneak up" to the desired pressure ;-)

http://bikeblather.blogspot.com/

Last edited by: Tom A.: Jun 25, 16 19:33

Re: More Data From Silca - Tire Pressure & Comfort [TRIing2Run] [ In reply to ]

Jun 26, 16 8:39

Post #23 of 31 Views: 6016

TRIing2Run wrote:

For bike tire pressures, it will need to be quite tall. The other option would be to go really old school and get one filled with mercury.

Valid point. You'd need something close to 200 ft tall.
But if we're already going to the lengths of filling tires with nitrogen, may as well do a mercury manometer. The mechanics already huff plenty of tubie glue; how much worse can Hg be? You'd want it to be about 25 ft tall (25 ft = 7620 mmHg = 147 psi. Because you never want to max out your gauge, of course). That could totally fit on a pro team's bus. But then you'd need an accurate thermometer to modify your calculations for the density of the mercury.

Re: More Data From Silca - Tire Pressure & Comfort [iank] [ In reply to ]

Jun 29, 16 12:56

Post #24 of 31 Views: 5791

The latest part of the series is live and even has a Slowtitch mention!

Part3B: FAQ and Questions Answered

http://www.SILCA.cc
Check out my podcast, inside stories from more than 20 years of product and tech innovation from inside the Pro Peloton and Pro Triathlon worlds!
http://www.marginalgainspodcast.cc

Re: More Data From Silca - Tire Pressure & Comfort [joshatsilca] [ In reply to ]

Jul 1, 16 9:47

Post #25 of 31 Views: 5618

Thanks for the information you are publishing.

Re: More Data From Silca - Tire Pressure & Comfort [TRIing2Run] [ In reply to ]

Jul 1, 16 10:53

Post #26 of 31 Views: 1672

Thanks, currently working on the last details of next week's piece on Crr... gonna be a fun one!
J

http://www.SILCA.cc
Check out my podcast, inside stories from more than 20 years of product and tech innovation from inside the Pro Peloton and Pro Triathlon worlds!
http://www.marginalgainspodcast.cc

Re: More Data From Silca - Tire Pressure & Comfort [joshatsilca] [ In reply to ]

Jul 4, 16 15:08

Post #27 of 31 Views: 1579

joshatsilca wrote:

Thanks, currently working on the last details of next week's piece on Crr... gonna be a fun one!
J

It will be interesting to see how things align with the late Jobst Brandt's thoughts on the topic:

jbrandt wrote:

From: jbrandt@hpl.hp.com (Jobst Brandt)
Newsgroups: rec.bicycles.tech Subject: Re: Tire question for Jobst
Date: 11 Jun 1999 18:49:16 GMT Brian Nystrom writes:
> In your rolling resistance testing, did you ever do any comparison
> of the effects of tire pressure on rolling resistance on a rough
> surface or was it all done on smooth surfaces? I've heard that high
> tire pressures can increase rolling resistance on rough surfaces,
> since they are less able to absorb the irregularities. Any credence
> to this?

Rough surface tests are not generally performed because they affect tires equally with varying inflation. I suppose for curiosity, a test on a drum with intermittent ribs widely spaced could do this, but I believe it has nothing to do with practical tire performance. The possibility that RR increases for tires on some surfaces is an often discussed subject, especially by riders who do not ride on a variety of surfaces with high pressure tires. In theory an increase would occur on a regular saw toothed surface riding up successive ramps only to land after a short free flight on the next ramp, thereby not rolling off the back side of the crest to gain any forward thrust. For those who ride over cattle guards either at the critical speed, this is a real effect and exactly emulates the ramp model. However, since road roughness is random and far smaller than the compliance of the tire, this scenario is unreal and does not occur. Tire deflection does not go to zero with high inflation. I have gotten snake bites with maximum safe inflation pressure on rough dirt roads. This is evidence of how much compliance a tire has even when inflated to these theoretical retarding pressures. It doesn't happen!

> I realize that the term "rough" is not descriptive, so for arguments
> sake, let's define it at as irregularities up to 1/2" in height or
> depth, which would be reasonably representative
> of.patched/cracked/erroded pavement.

Yes, any singular feature that causes lift-off has a retarding effect if there is not a series of randomly spaced similar ones on whose backside the tire lands as often as it lifts off. This occurs on an adversely ordered surface, such as a cattle guard or a series of botts dots. However, a tire that is run at lower inflation absorbs energy all the time including the larger bumps that it cannot entirely absorb anyway. Jim Papadopoulos has argued for lower inflation at great length ins this subject here on the net. Having ridden many miles on pave' and cobbles, I am convinced that although it may not be comfortable, high tire pressure is faster on even such rough surfaces. Jobst Brandt <jbrandt@hpl.hp.com>

My own personal findings indicate that on super duper rough chip seal, a modest increase in Crr can be observed with modestly higher pressures - maybe 10% or so in terms of watts @ 40 kph:

other field test data I've collected in the past suggests higher pressures aren't as bad as have been posited:

http://biketechreview.com/...-on-road-crr-results

...though, drawing conclusions based on field testing Crr and CxA is a tough piece of work when methodology lacks statistical power.

also, FWIW, bumpy roller tests conducted by two separate individuals (myself and Al Morrision) indicate decreasing Crr with increasing pressure:

http://www.biketechreview.com/...py_Data_BTR_rev1.pdf

ymmv,

=================
Kraig Willett
http://www.biketechreview.com - check out our reduced report pricing
=================

Re: More Data From Silca - Tire Pressure & Comfort [BikeTechReview] [ In reply to ]

Jul 4, 16 17:17

Post #28 of 31 Views: 1526

BikeTechReview wrote:

joshatsilca wrote:

Thanks, currently working on the last details of next week's piece on Crr... gonna be a fun one!
J

It will be interesting to see how things align with the late Jobst Brandt's thoughts on the topic:

jbrandt wrote:

From: jbrandt@hpl.hp.com (Jobst Brandt)
Newsgroups: rec.bicycles.tech Subject: Re: Tire question for Jobst
Date: 11 Jun 1999 18:49:16 GMT Brian Nystrom writes:
> In your rolling resistance testing, did you ever do any comparison
> of the effects of tire pressure on rolling resistance on a rough
> surface or was it all done on smooth surfaces? I've heard that high
> tire pressures can increase rolling resistance on rough surfaces,
> since they are less able to absorb the irregularities. Any credence
> to this?

Rough surface tests are not generally performed because they affect tires equally with varying inflation. I suppose for curiosity, a test on a drum with intermittent ribs widely spaced could do this, but I believe it has nothing to do with practical tire performance. The possibility that RR increases for tires on some surfaces is an often discussed subject, especially by riders who do not ride on a variety of surfaces with high pressure tires. In theory an increase would occur on a regular saw toothed surface riding up successive ramps only to land after a short free flight on the next ramp, thereby not rolling off the back side of the crest to gain any forward thrust. For those who ride over cattle guards either at the critical speed, this is a real effect and exactly emulates the ramp model. However, since road roughness is random and far smaller than the compliance of the tire, this scenario is unreal and does not occur. Tire deflection does not go to zero with high inflation. I have gotten snake bites with maximum safe inflation pressure on rough dirt roads. This is evidence of how much compliance a tire has even when inflated to these theoretical retarding pressures. It doesn't happen!

> I realize that the term "rough" is not descriptive, so for arguments
> sake, let's define it at as irregularities up to 1/2" in height or
> depth, which would be reasonably representative
> of.patched/cracked/erroded pavement.

Yes, any singular feature that causes lift-off has a retarding effect if there is not a series of randomly spaced similar ones on whose backside the tire lands as often as it lifts off. This occurs on an adversely ordered surface, such as a cattle guard or a series of botts dots. However, a tire that is run at lower inflation absorbs energy all the time including the larger bumps that it cannot entirely absorb anyway. Jim Papadopoulos has argued for lower inflation at great length ins this subject here on the net. Having ridden many miles on pave' and cobbles, I am convinced that although it may not be comfortable, high tire pressure is faster on even such rough surfaces. Jobst Brandt <jbrandt@hpl.hp.com>

My own personal findings indicate that on super duper rough chip seal, a modest increase in Crr can be observed with modestly higher pressures - maybe 10% or so in terms of watts @ 40 kph:

other field test data I've collected in the past suggests higher pressures aren't as bad as have been posited:

http://biketechreview.com/...-on-road-crr-results

...though, drawing conclusions based on field testing Crr and CxA is a tough piece of work when methodology lacks statistical power.

also, FWIW, bumpy roller tests conducted by two separate individuals (myself and Al Morrision) indicate decreasing Crr with increasing pressure:

http://www.biketechreview.com/...py_Data_BTR_rev1.pdf

ymmv,

What size rim and what tire were you using? Also, how much do you weigh.

Save: $50 on Speed Hound Recovery Boots | $20 on Air Relax| $100 on Normatec| 15% on Most Absorbable Magnesium

Blogs: Best CHEAP Zwift / Bike Trainer Desk | Theragun G3 vs $140 Bivi Percussive Massager | Normatec Pulse 2.0 vs Normatec Pulse | Speed Hound vs Normatec | Air Relax vs Normatec | Q1 2018 Blood Test Results | | Why HED JET+ Is The BEST value wheelset

Re: More Data From Silca - Tire Pressure & Comfort [BikeTechReview] [ In reply to ]

Jul 5, 16 9:51

Post #29 of 31 Views: 1440

BikeTechReview wrote:

also, FWIW, bumpy roller tests conducted by two separate individuals (myself and Al Morrision) indicate decreasing Crr with increasing pressure:

http://www.biketechreview.com/...py_Data_BTR_rev1.pdf

Some important notes about Al's testing, of which you may, or may not be aware...but which are important for others to put it into context:

1. Al applied wire "bumps" to only 1 roller of a 2-roller rear setup. This means that only have the contact patch load of the rear wheel was being "energized" (i.e. only slightly more than half the load on the "bumpy" contact).

2. The wires were fairly small diameter. As we've seen in the previous Silca data (and data from Damon Rinard) the smaller the object, the lower the effective spring constant for a given tire/wheel at a given pressure.

3. Al's rollers are plastic, which will have more inherent flexibility than aluminum rollers, or even a typical road surface.

Knowing all of that, even Al has told me himself that he doesn't think his original "bumpy roller" test was particularly enlightening.

http://bikeblather.blogspot.com/

Re: More Data From Silca - Tire Pressure & Comfort [Thomas Gerlach] [ In reply to ]

Jul 5, 16 20:35

Post #30 of 31 Views: 1352

Thomas Gerlach wrote:

BikeTechReview wrote:

joshatsilca wrote:

Thanks, currently working on the last details of next week's piece on Crr... gonna be a fun one!
J

It will be interesting to see how things align with the late Jobst Brandt's thoughts on the topic:

jbrandt wrote:

From: jbrandt@hpl.hp.com (Jobst Brandt)
Newsgroups: rec.bicycles.tech Subject: Re: Tire question for Jobst
Date: 11 Jun 1999 18:49:16 GMT Brian Nystrom writes:
> In your rolling resistance testing, did you ever do any comparison
> of the effects of tire pressure on rolling resistance on a rough
> surface or was it all done on smooth surfaces? I've heard that high
> tire pressures can increase rolling resistance on rough surfaces,
> since they are less able to absorb the irregularities. Any credence
> to this?

Rough surface tests are not generally performed because they affect tires equally with varying inflation. I suppose for curiosity, a test on a drum with intermittent ribs widely spaced could do this, but I believe it has nothing to do with practical tire performance. The possibility that RR increases for tires on some surfaces is an often discussed subject, especially by riders who do not ride on a variety of surfaces with high pressure tires. In theory an increase would occur on a regular saw toothed surface riding up successive ramps only to land after a short free flight on the next ramp, thereby not rolling off the back side of the crest to gain any forward thrust. For those who ride over cattle guards either at the critical speed, this is a real effect and exactly emulates the ramp model. However, since road roughness is random and far smaller than the compliance of the tire, this scenario is unreal and does not occur. Tire deflection does not go to zero with high inflation. I have gotten snake bites with maximum safe inflation pressure on rough dirt roads. This is evidence of how much compliance a tire has even when inflated to these theoretical retarding pressures. It doesn't happen!

> I realize that the term "rough" is not descriptive, so for arguments
> sake, let's define it at as irregularities up to 1/2" in height or
> depth, which would be reasonably representative
> of.patched/cracked/erroded pavement.

Yes, any singular feature that causes lift-off has a retarding effect if there is not a series of randomly spaced similar ones on whose backside the tire lands as often as it lifts off. This occurs on an adversely ordered surface, such as a cattle guard or a series of botts dots. However, a tire that is run at lower inflation absorbs energy all the time including the larger bumps that it cannot entirely absorb anyway. Jim Papadopoulos has argued for lower inflation at great length ins this subject here on the net. Having ridden many miles on pave' and cobbles, I am convinced that although it may not be comfortable, high tire pressure is faster on even such rough surfaces. Jobst Brandt <jbrandt@hpl.hp.com>

My own personal findings indicate that on super duper rough chip seal, a modest increase in Crr can be observed with modestly higher pressures - maybe 10% or so in terms of watts @ 40 kph:

other field test data I've collected in the past suggests higher pressures aren't as bad as have been posited:

http://biketechreview.com/...-on-road-crr-results

...though, drawing conclusions based on field testing Crr and CxA is a tough piece of work when methodology lacks statistical power.

also, FWIW, bumpy roller tests conducted by two separate individuals (myself and Al Morrision) indicate decreasing Crr with increasing pressure:

http://www.biketechreview.com/...py_Data_BTR_rev1.pdf

ymmv,

What size rim and what tire were you using? Also, how much do you weigh.

brake track to brake track measured 19.6mm - I have used many different tires over the years to create demand plots similar to the above; however for this particular plot I used a vittoria 700x20c zaffiro that had an installed width of 20.8mm at 120 psi.

All-up bike/kit/rider mass at the time was 84kg IIRC.

=================
Kraig Willett
http://www.biketechreview.com - check out our reduced report pricing
=================

Re: More Data From Silca - Tire Pressure & Comfort [Tom A.] [ In reply to ]

Jul 5, 16 21:05

Post #31 of 31 Views: 1344

Tom A. wrote:

BikeTechReview wrote:

also, FWIW, bumpy roller tests conducted by two separate individuals (myself and Al Morrision) indicate decreasing Crr with increasing pressure:

http://www.biketechreview.com/...py_Data_BTR_rev1.pdf

Some important notes about Al's testing, of which you may, or may not be aware...but which are important for others to put it into context:

1. Al applied wire "bumps" to only 1 roller of a 2-roller rear setup. This means that only have the contact patch load of the rear wheel was being "energized" (i.e. only slightly more than half the load on the "bumpy" contact).

that's what I did in my testing as well. At the time, my well-calibrated meat in the seat/supercomputer sensor said - "whoa, that's f'in bumpy!". It's also interesting to note that Al's reported bumpy Crr increased by about 30% over the smooth roller configuration with his "half-load-energized" setup. Does this make his setup more lossy than what is reported elsewhere? I dunno...but, my setup was f'in bumpy!

Quote:

2. The wires were fairly small diameter. As we've seen in the previous Silca data (and data from Damon Rinard) the smaller the object, the lower the effective spring constant for a given tire/wheel at a given pressure.

I had small bump heights as well: 1-2 mm tall. They were pretty wide, though, and I had quite a few of them - rubber deposited on the bumps too. I took some video when I did this experiment back in 2010 and there was some discussion on the BTR forum as well:

video here (woohoo - hear those bumps hum!):

www.biketechreview.com/images/bumpy_rollers_090610_lores.wmv

thread here:
http://biketechreview.com/...losses-in-human-body

Quote:

3. Al's rollers are plastic, which will have more inherent flexibility than aluminum rollers, or even a typical road surface.

mine were 4.5" aluminum as shown in the video above.

=================
Kraig Willett
http://www.biketechreview.com - check out our reduced report pricing
=================

Our Partners

transition-DOT-area-AT-slowtwitch-DOT-com

Advertise with us

©1999-2024 Slowtwitch, Inc., and Slowtwitch.com
Reproduction of material from any Slowtwitch.com page
without written permission is strictly prohibited.