Okay Got the new bike together with new Mich pro 3’s on my old 2007 Flashpoint 60’s. Rear wheel has a wheel builder disc. Ordered latex and butyl tubes. Latex 60mm presta valve and butyl 80mm presta valve. I have a nice hill in front of a cemetary (In case I fall doing 50 I dont have far to go.) with a little hill on backside of big hill. After my three 12 mile loops I am going to coast down with Butyl tubes first and chalk where bike stops and note speeds along the way I might even break speeds down by 100’ , 200’ ,300’ and so on. Then go home and switch tubes to latex ( balloon tubes@14.95 per ) and do all over. Hopefully it will be enough of a difference to warrant having such light fragile latex tubes on bike. Of course Tom Demmerly probably did this already but what the hell I am sort of in a taper and need something to do. Ask my wife and I should be mowing the lawn. Thursday looks like a nice sunny day to start.
the latex tubes aren’t fragile
balloon tubes? is this a brand?
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Latex tubes are not fragile. Yes. Care must be taken on initial install and they do lose air much more quickly than butyl tubes. But, that’s really the only difference you’re likely to notice.
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I predict any performance distance will be lost in the noise on your planned rolldown test. Unless you get the exact same weather conditions, ride exactly the same line in exactly the same position, start from exactly the same point & speed, etc., etc., etc… And, if you plan to record speeds along the way like you said, the noise will just get louder.
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ProBikeKit had Michelin AirComp Latex tubes in 60mm valve for ~$10 last time I looked/bought.
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I doubt Tom Demerly’s done this test. (Isn’t he a tubie rider???) MAYBE, Tom Anhalt. But, I think he probably just trusted Al’s roller data.
Steve
Well this is the first time I ever touched a latex tube and it seemed just by feel and weight they were more fragile then butyl. I called them balloon tubes because they felt and smelled like the water balloons I was fighting with my kids with yesterday. I will take the same line down the hill. I did not think of the test another slowtwicher had told me to try this way and see. So i said to myself " Myself I might as well." As for wind variables the road goes east to west where ther are usually light to non-crosswinds and is covered both sides by trees. Jack I thought you would like since I am using a disc. I thought of biulding a wind tunnel in backyard but with the economy and losing 40% of my 401k I had to adjust my spending habits.
- I predict any performance distance will be lost in the noise on your planned rolldown test. Unless you get the exact same weather conditions, ride exactly the same line in exactly the same position, start from exactly the same point & speed, etc., etc., etc… And, if you plan to record speeds along the way like you said, the noise will just get louder.
Maybe I don’t get it, but as I understand, latex tubes offer better rolling resistance in exchange for some fragility. But if latex can’t consistently show better performance over the “noise” in this type of test, then do they really offer any benefit at all?
I’m glad you’re doing this test and eagerly await the results.
BTW, to answer the criticism of ‘noise’ you should roll down multiple times in both configurations looking for the average or median roll-out point.
ie. roll down 3 times with butyl and mark all 3 with chalk then note either the ‘average’ finish spot or median finish spot then repeat with latex.
Use the same tire pressure both times. If you are doing your whole training ride before the butyl rolldown then just quickly returning with latex you won’t be able to guarantee the same pressure because the tires could heat up (or cool down) during your ride creating a small variation in pressure. But personally, I think that’s getting a bit more ‘scientific’ than you’d need to worry about.
Please let us know.
I’m going to subscribe to this thread so I will be sure to see the results.
Okay Got the new bike together with new Mich pro 3’s on my old 2007 Flashpoint 60’s. Rear wheel has a wheel builder disc. Ordered latex and butyl tubes. Latex 60mm presta valve and butyl 80mm presta valve. I have a nice hill in front of a cemetary (In case I fall doing 50 I dont have far to go.) with a little hill on backside of big hill. After my three 12 mile loops I am going to coast down with Butyl tubes first and chalk where bike stops and note speeds along the way I might even break speeds down by 100’ , 200’ ,300’ and so on. Then go home and switch tubes to latex ( balloon tubes@14.95 per ) and do all over. Hopefully it will be enough of a difference to warrant having such light fragile latex tubes on bike. Of course Tom Demmerly probably did this already but what the hell I am sort of in a taper and need something to do. Ask my wife and I should be mowing the lawn. Thursday looks like a nice sunny day to start.
Have fun with your “testing”…but, as others have said, you’re going to have a hard time “teasing out” the difference using that sort of test. There are just too many uncontrolled/uncontrollable confounding variables. Now, that doesn’t mean the benefit isn’t there…in fact, multiple tests have shown the benefit to be an ~15% drop in Crr…it’s just that your test method isn’t sensitive enough to pick it out. No matter, a benefit is a benefit, and all other things being equal, you’ll be faster with them than with the butyl tubes.
I’ll bet the first thing you’ll notice is the “feel” of them though…as much as I don’t trust the human sense of “feel”, it’s a very palpable difference IMHO 
Went for a 35 miler on training bike then 6.5 mile run because it rained last night, fun little brick. Cleared up nice but did not want to take new bike out,alot of wet grit under the dry stuff. Will tri the butyl’s tommorow and note finds then the latex friday again weather permitting. Did want to swim and run so maybe I will just throw the bike on the car and drive out there. This way I can bringa air pump to make sure pressures are the same. Also take a can of spray paint to mark so it wont wash away. I am about 156 lbs on a good day. Whats the best pressure I should ride on ? All this might even help with my Devilman race may 9th as a added Benefit. I will mark each spot and snap photos when done. Looks like I got 5-6 hill climbs tommorow.
Pressure will be set to the recommended PSI on the tire sidewall. Any difference seen between the 2 tubes will also exist at all other pressures I would guess.
It would be a separate test, but worthwhile also to play with different pressures (not changing tubes) to find the pressure that works best for you, your tires, and your pavement (assuming you can find pavement for a rolldown test that’s analogous to what you’d usually race).
BTW, for rolldown testing the IDEAL hill, as far as I can conceptualize, would be very long and gradual and gently fade away to a flat at the bottom. By being very gradual it would keep your running speed lower and minimize the aerodynamic factor and by gently fading away it will increase the amount of rollout at the end as you begin decelerating.
But I am hopeful that any long hill should be suitable.
The closest hill I have in mind has a small upward hill at the end. All things being the same I think the latex tubes should go further up the small hill. With the mich 3 tires 116 psi is the recomended pressure. My races are all in different cities. Even with my training rides I can tell the difference in the asphalt as to how the resistance is. It’s actually amazing the differences in resistance with just the different asphalt. If I start out fresh I should be able to keep a good aero position through out test. Hell I am only rolling , sort of like staying in a tuck while downhill skiing. Now thats easy!
Sorry about that blue email thingy didnt know by how I wrote that it would do that. You clicked on it a couple times didnt you . LOL!!!
“Pressure will be set to the recommended PSI on the tire sidewall”
Sorry, no. This is the MAXIMUM pressure for the tire. At 156 lbs rider weight the pressure in a PR3 should be about 109 psi (according to Michelin).
“Pressure will be set to the recommended PSI on the tire sidewall”
Sorry, no. This is the MAXIMUM pressure for the tire. At 156 lbs rider weight the pressure in a PR3 should be about 109 psi (according to Michelin).
Fair enough. Either way it’s a parameter that needs to be controlled.
Thought the little chart on the tire package showed 116 psi. Will look again if i did not throw away. If I did I will use your pressure. of 109
When I bought the PR3s for my bike I did a lot of research on tire pressure. Actually contacted the manufacturer and that’s what they gave me. (I weigh ~153 “ready to ride” and set my tires at 109 to start. If I’m riding rough roads, or just want a little smoother ride, I’ll stop and let a little out. (I don’t measure again; I just ‘pop’ the valve quickly a couple of times with my finger.)
They had a little chart on the side of the plastic package. I think I used 160lbs when I looked at it.
In case you lose the chart
http://www.michelinbicycletire.com/michelinbicycle/index.cfm?event=airpressure.view
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For those just reading this I am trying to figure out if there is any significant gains by using Latex tubes over Butyl tubes.
I did the Butyl tube distance test yesterday. I did five tri’s at the hill. I have time, distance, avg speed and max speed for all but the 1st one which I have onkly max speed. Tire pressure was 110 psi.
Here is the butyl tube data taken on my polar s725i:
1st run:
max speed: 31.4
distance: 0.6 mile
2nd run:
distance: 0.6 mile
time: 2 min 56 sec.
max speed: 31.7
**average speed:**16.2mph
3rd run:
dist: 0.7 mile
**Time: **2min 23 sec
max speed: 32.1
average speed: 18.1 mph
4th run:
dist: 0.8 mile
Time: 2 min 55 sec
max speed: 31.6 mph
average speed: 15.9 mph
5th run:
dist: 0.7 mile
time: 2 min. 49 sec.
max speed: 32 mph
avg speed : 17.7 mph
Some big gaps with distance and time but I blame that on wind as it was pushing me a little. I tried to keep on the white line each time so to keep the same line. I marked the spots so after I do the latex tube I will measure by feet also. Unfortunalty today by the time it cleared up from raining I had my son. Wind condition was about the same. Hopefully monday I can do latex tubes. They are installed and ready to go. Just as long as I installed good and dont get a pinched tube. If the latex is more then a 1000’ better there might be a problem as it goes into another little hill where I tested. At least will no if they are a 1000’ or more better. I do have pics to down load and will when get a chance.
Thanks for going through all this effort, I’m following with interest.
I’m a bit disappointed to find all the variability. The latex tubes will be far better indeed if you can find a clear improvement that’s beyond that standard of deviation.
I did rolldown testing once, and perhaps it was the stillness of the day, or the road section I chose…but I was within 10 feet each time after perhaps 500meters. It just shows how important it is to establish you repeatability first (the error margin of your test protocol).
Thanks for doing and posting this test, it’s pretty interesting. It’s odd that your 4th run is the slowest yet the longest. Did you mark the end points on the road? One of the problems with measuring distances with odometers is that 1 revolution of the wheel can change your results.
Anxiously awaiting latex results.