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  1. #1
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    Narrowest tires??

    We ride a Co-Motion Speedster and presently run 28mm GatorSkins though we will be upper these to 32mm for touring.
    What is the narrowest width one might run when not touring?

  2. #2
    Senior Member VaultGuru's Avatar
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    700x23's are my goto tires. never had a problem in 10 years.

  3. #3
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    Quote Originally Posted by VaultGuru View Post
    700x23's are my goto tires. never had a problem in 10 years.
    What's your team's weight, inc bike?

  4. #4
    Senior Member zonatandem's Avatar
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    Agree on 700x23s.
    Used those for decades, and before that 27x1 1/8.
    Currently runnin' 700x25s as we no longer ride as aggressively at our age (80/77).
    Pedal on TWOgether!
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    Senior Member obrentharris's Avatar
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    Is there really a one-size-fits-all answer to the question of minimum tire size? It seems a lot depends on the surfaces on which you ride and the amount of weight the tires have to carry. As an example many of our rides include some gravel sections or roads with very torn-up surfaces. On one of the local gravel bike path sections I have pinch-flatted on three out of five attempts with 23's on my single bike. We run the Gatorskin 28's on our tandem and so far no pinch flats on that same section. I don't think we would be so lucky with 23's on the tandem. In a way I'm envious of those folks whose roads are smooth enough to allow them to run 23's... but I do love the "character" of our local roads too.
    Brent

  6. #6
    Tandem Vincitur Ritterview's Avatar
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    Tire width and inflation pressure is a hoary topic on the tandem forum. It neccessarily involves team weight. This graph is at least a point of reference, it dates back to an article in Bicycling Magazine 1989, and is extrapolated (I think by Precision Tandems) for tandem team weights.



    So, you'd figure your team + bicycle weight, and then consult the chart. Figuring the highest inflation pressure on a clincher would be at most 140 psi (or that embossed on the sidewall), determine which is the narrowest tire that can accommodate your team + bike weight.

    I don't know about this graph. I'd think that actual ideal pressures at each weight would not be so strictly linear.

  7. #7
    just another gosling Carbonfiberboy's Avatar
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    305 lb. team on a Speedster, 700 X 23 at 140 lbs. works fine. We have switched to 25c, though, finding that our 23c that would take 140 lbs. were a little delicate. 25c at 120 lbs. also works, though I wouldn't mind a tire that could take a little more pressure. We run 28c at 115 when we tour.

  8. #8
    Senior Member Homeyba's Avatar
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    I don't about that chart Ritterview. My team is in the 350 range and run 23's and 25's at 120psi. According to that chart we should be inflating our tires to something like 160psi for the 25's and 200psi for the 23's (if I'm reading that chart correctly). None of my tires are even rated for those pressures.
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  9. #9
    Senior Member waynesulak's Avatar
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    Quote Originally Posted by Homeyba View Post
    I don't about that chart Ritterview. My team is in the 350 range and run 23's and 25's at 120psi. According to that chart we should be inflating our tires to something like 160psi for the 25's and 200psi for the 23's (if I'm reading that chart correctly). None of my tires are even rated for those pressures.
    The chart is attempts to give the pressures at which the tire deflection is held constant. It is not a chart for safety but rather the author's feeling of the pressures yielding the lowest rolling resistance. I feel that chart is a good starting point but as Homeyba points out there is much room for teams to go outside its recommendations depending on what your team likes and the road surfaces encountered.

    I think most people would agree that when holding the pressure constant a heavier team will deform the tire more than a lighter team. Likewise that more tire deformation can increase rolling resistance. As a result I believe the chart does a good job pointing out that if 23mm tires are at 120 psi is the fastest setup for a 200 lb load then it may not be for a 350lb load.

    Personally I like wider tires so that I can ride faster and more aggressively over cracked rough roads, railroad tracks, and cattle grates.

    Below is a link to a good discussion of the chart, tire choice and inflation at Precision Tandems.

    http://www.precisiontandems.com/arttiresbymark.htm
    Last edited by waynesulak; 06-21-12 at 07:31 AM.

  10. #10
    pan y agua merlinextraligh's Avatar
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    Agreed the chart is high, at least for our team at 350lbs. We typically ride 25mm at 110lbs or so with no problems.

    On the TT wheels, we have 23mm tires and run them 115 lbs.

    As to rolling resistance, there's more and more evidence that wider = lower rolling resistance, and a trend amongst pros to go to wider tires, with some running 25mm tires on single bikes.

    That would seem to indicate that from a rolling resistance point of view going below 25mm, even 28mm on a tandem might actually be counterproductive.

    Balanced against that, however is the fact that wider tires (setting aside issues of tire/rim interface) are going to offer more aerodynamic resistance.

    According to the Zipp rep running 25mm tires on our 808's costs 8 watts per wheel compared to 23mm. Hence the 23mm for TT's. (although with the new wider firecrest rims that might be different.)
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  11. #11
    What??? Only 2 wheels? jimmuller's Avatar
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    Quote Originally Posted by merlinextraligh View Post
    As to rolling resistance, there's more and more evidence that wider = lower rolling resistance
    It is really more evidence or just more discussion? (Unlike politics and high-visibility trials, having a lot of people saying what they think doesn't make it true. Come to think of it, it doesn't work in those fields either.)

    There would seem to be a lot of variables involved, road surface and quality, weight, avg and typical high speed, reliability, etc. My personal experience is that my tires seem to roll further when pumped up. But that could be an incorrect impression. Impressions are always suspect.

    Regardless, it isn't a huge factor. On the other hand, reliability is very important to us. Patching or replacing a rear tube on our tandem would be a royal pain. My solo bikes are different cases because I use them in different situations. Commuting favors reliability, sport riding favors speed and comfort, racing (which I don't do) would favor just speed.
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  12. #12
    Senior Member waynesulak's Avatar
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    Quote Originally Posted by merlinextraligh View Post
    Agreed the chart is high, at least for our team at 350lbs. We typically ride 25mm at 110lbs or so with no problems.

    On the TT wheels, we have 23mm tires and run them 115 lbs.

    As to rolling resistance, there's more and more evidence that wider = lower rolling resistance, and a trend amongst pros to go to wider tires, with some running 25mm tires on single bikes.

    That would seem to indicate that from a rolling resistance point of view going below 25mm, even 28mm on a tandem might actually be counterproductive.

    Balanced against that, however is the fact that wider tires (setting aside issues of tire/rim interface) are going to offer more aerodynamic resistance.

    According to the Zipp rep running 25mm tires on our 808's costs 8 watts per wheel compared to 23mm. Hence the 23mm for TT's. (although with the new wider firecrest rims that might be different.)
    Granted a wider tire will give more air resistance than a narrow one and that the Zipp rims are designed for best performance with 23mm tires. I assume the 8 watts per wheel statement is somewhat of a simplification using some assumptions about wind direction and speed but that it is a fair estimation.

    What we need is some serious testing of rolling resistance quantified in watts lost. The folks at Zipp have quantified the additional cost in watts of the wider tires but what we don’t know is the cost in rolling resistance of the narrower tires. Of course that value would depend on the road surface. There are always tradeoffs.

    The speeds we typically ride at are much lower than merlinextralight’s time trial speed so my guess is that rolling resistance trumps aero on our case. Unfortunately it is just a guess. On long rides I have also found the smooth ride of wider tires at lower pressures provides a power benefit in the last hour of the ride. This is impossible to qualify so each team is left to ride what they feel subjectively works best for them.

  13. #13
    Senior Member diabloridr's Avatar
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    Quote Originally Posted by waynesulak View Post
    The speeds we typically ride at are much lower than merlinextralight’s time trial speed so my guess is that rolling resistance trumps aero on our case.
    Bingo, Wayne gets it.

    Any statements bout aero benefits such as "X watts saved" or "X seconds faster in 40 km" must state the speed the benefit was measured at to be of any use in making equipment decisions.

    OTOH, rolling resistance changes are not speed dependent, AFAIK.

  14. #14
    pan y agua merlinextraligh's Avatar
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    Quote Originally Posted by diabloridr View Post
    Bingo, Wayne gets it.

    Any statements bout aero benefits such as "X watts saved" or "X seconds faster in 40 km" must state the speed the benefit was measured at to be of any use in making equipment decisions.

    OTOH, rolling resistance changes are not speed dependent, AFAIK.
    True on the aero data, and Zipp typically runs their numbers at 30mph. That seems awfully fast, however, as the speed drops, the watts/mph difference drops, but the time advantage for a given distance actually increases.

    It also does depend on yaw angle , with different wheels working better at different wind angles. Unfortunately, if you don't know have access to a wind tunnel, getting precise answers to various combinations isn't very common.


    As for rolling resistance, I believe rolling resistance increases with speed in a pretty much linear fashion, whereas wind resistance increases as a squared function of speed. So it's not the RR doesn't increase, its just that the increase in wind resistance is much greater, and becomes a greater consideration as speeds increase.
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  15. #15
    pan y agua merlinextraligh's Avatar
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    Quote Originally Posted by jimmuller View Post
    It is really more evidence or just more discussion? (Unlike politics and high-visibility trials, having a lot of people saying what they think doesn't make it true. Come to think of it, it doesn't work in those fields either.)

    There would seem to be a lot of variables involved, road surface and quality, weight, avg and typical high speed, reliability, etc. My personal experience is that my tires seem to roll further when pumped up. But that could be an incorrect impression. Impressions are always suspect.

    Regardless, it isn't a huge factor. On the other hand, reliability is very important to us. Patching or replacing a rear tube on our tandem would be a royal pain. My solo bikes are different cases because I use them in different situations. Commuting favors reliability, sport riding favors speed and comfort, racing (which I don't do) would favor just speed.
    As for data, a few examples:

    http://www.schwalbetires.com/tech_in...resistance#why

    http://velonews.competitor.com/2012/...rethren_209268

    http://velonews.competitor.com/2012/...-data-schwalbe

    As for tires pumped up high feeling faster, they do because rock hard tires bounce over imperfections and give a "responsive, lively" feel.

    Tires not pumped rock hard tend to abosorb imperfections by deforming, not bouncing over them, which results in less rolling resistance, but doesn't feel as lively. So the point is that the tires need to have the right air pressure for the optimal amount of deflection. And the data on that is showing that it's a lot lower pressure than many people have thought in the past.
    Last edited by merlinextraligh; 06-21-12 at 10:14 AM.
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  16. #16
    Senior Member diabloridr's Avatar
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    Quote Originally Posted by merlinextraligh View Post
    True on the aero data, and Zipp typically runs their numbers at 30mph. That seems awfully fast, however, as the speed drops, the watts/mph difference drops, but the time advantage for a given distance actually increases.
    Agreed, data at 25 MPH would be more useful for amateur racers and data at 20 MPH more useful for recreational riders. But then the Zipp claims wouldn't look as impressive (not to single them out).

    I've never worked the math, but I suspect the time advantage for a given distance increasing would be a constant if calculated in percentage terms.
    Last edited by diabloridr; 06-21-12 at 10:31 AM. Reason: typo

  17. #17
    Senior Member waynesulak's Avatar
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    Quote Originally Posted by diabloridr View Post
    Bingo, Wayne gets it.

    Any statements bout aero benefits such as "X watts saved" or "X seconds faster in 40 km" must state the speed the benefit was measured at to be of any use in making equipment decisions.

    OTOH, rolling resistance changes are not speed dependent, AFAIK.

    To give some perspective attached are a couple examples: First a magazine article about a test of various aero wheels that states that there is no measurable effect below 30 kmh (18.5 mph). Another paper by Zipp used a testing speed of 30 mph.

    I have attached pages of these articles. I could not attach the PDFs due to the file size limitations so they are attached as JPG files.

    Wow in the time I got around to posting this I can see others have posted similar information. I think we all agree.

  18. #18
    rebmeM roineS JanMM's Avatar
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    From the first Velonews article: Wider tires have less rolling resistance.
    Hooray! We can keep riding our 40mm tires! 32 is the smallest we've gone on tandems.
    RANS V3 (steel), RANS V-Rex, RANS Screamer

  19. #19
    Senior Member Homeyba's Avatar
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    The only problem I have with this "research" is that it's all done by Schwalbe who has an obvious intrest in the outcome of the research. Even the data supplied by Zinn in the Velonews article is from Schwalbe. Bicycle Quarterly also did some reseach and found Grand Bois to have the least rolling resistance but they sell Grand Bois. I know of one other article that was done by a German magazine that came to the conclusion that 23mm Continental tires had the lowest rolling resistance. Guess where their tesing was done??? Yeah, at a Continental facility. Until some "research" is done by someone who doesn't have a pony in the show I'll read all that with a grain of salt.
    It doesn't get harder, you just go slower.

  20. #20
    hors category TandemGeek's Avatar
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    Frankly, this is all about splitting hairs in the grand scheme of things unless we're talking about extremes, i.e., riding 23mm high pressure on chip seal is pretty friggin extreme and incredibly inefficient, never mind painful. 25mm is even a poor choice under those conditions.

    The trick is matching tires construction, size and pressure -- as well as wheels -- to riding styles, conditions and expectations relative to personal preference and that's something that each cyclist needs to do, often times through a little experimentation. Try different pressures, different size tires and keep your mind open with regard to your own personal impressions, likes and dislikes.

    After all, I don't care how good certain foods are for me, I simply don't like the way they taste or their texture. While higher fuel mileage cars make a lot of sense, I split the difference by riding high-mileage motorcycles during the week for my commute (sorry, a bicycle won't work for me) and have my truck for the weekend because high-mileage vehicles are either too impractical for my all-around needs or just not enjoyable to drive. If I could work a 3rd car into our budget and garage we'd probably have a VW Jetta TDI Sportwagon in the stable because Debbie isn't giving up her little S2000 for a sportwagon anytime too soon. Again, personal preference.

    Just my .02. And, as far as bicycle tire selection goes, I always reserve the right to adapt to changing preferences and expectations by making different tire choices in the future.

  21. #21
    just another gosling Carbonfiberboy's Avatar
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    All the above rolling resistance data and testing is nonsense. All of this nonsense requires that every width of tire be inflated to the same pressure. If we did that, of course the data would be valid. But no one does that. For one thing, sidewall max pressure labels forbid it. I run 23c at 140, 28c at 115, most wider tires have max pressures in the 65-85 lb. range. So the protocols of these tests are silliness. As far as lower pressure tires being faster on rough surfaces, lab testing has shown that all tires, on both rough and smooth surfaces, will show decreased rolling resistance as pressure in increased. There are no tests which show less rolling resistance at lower pressures on the same tire, no matter what the surface. Jobst Brandt had a good post on this a while back. There are unbiased tire rolling resistance tests:
    http://biketechreview.com/tires/roll...75-roller-data

    From this data, it is obvious that the thinner the tire, the lower the resistance, all other things being equal. Duh. Unfortunately, the test protocol has all tires run at the same pressure, which again is nonsense. They should all be run at the max sidewall pressure. So this data is not believable, either, except that it does show the trend I mention. It is the thinness of Grand Bois tires for their pressure rating that gives them low rolling resistance, not their width per se.

  22. #22
    Senior Member
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    Actually there are some tests with the same tires tested at different pressures. Unfortunately most of the tests are for tires that are appropriate for recumbants and trikes.
    http://www.microsofttranslator.com/B...l%2Fbandentest

  23. #23
    Senior Member obrentharris's Avatar
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    Quote Originally Posted by Carbonfiberboy View Post
    As far as lower pressure tires being faster on rough surfaces, lab testing has shown that all tires, on both rough and smooth surfaces, will show decreased rolling resistance as pressure in increased. There are no tests which show less rolling resistance at lower pressures on the same tire, no matter what the surface.
    You are quite right as far as rolling resistance goes, and on smooth surfaces decreased rolling resistance is probably the most important performance factor effected by tire pressure. But on the rough surfaces on which some of us ride our road tandems increased pressure is not always faster. For those who ride MTB tandems this is true in spades. Three related factors; control, flotation, and traction, can be more important than rolling resistance and are often increased as tire pressure is decreased. If you wish to test this out take your bike down to the local elementary school, inflate your 35mm tires to the maximum pressure which you consider safe and take a ride through the sandbox. Now decrease your tire pressure by half and try it again. Another test? Find a trail or gravel bike path that has been chopped up by muddy horse hooves, frost heave, or gophers. Try the same tire pressure tests. Time yourself if you like. You may be surprised to discover that lower air pressure can make you faster. Those of us who race cyclocross discovered this long before my time. Our race tires are typically capable of pressures of 55 to 70 psi but we very seldom run them anywhere near those pressures. Indeed we have found that we often get better lap times with our tires inflated to less than half those numbers. The loss of speed on the asphalt portions of the course are more than made up for by the increased traction, control, and flotation on the rest of the course that we get from running our tires with 25 pounds of pressure.
    Brent

  24. #24
    just another gosling Carbonfiberboy's Avatar
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    Quote Originally Posted by obrentharris View Post
    You are quite right as far as rolling resistance goes, and on smooth surfaces decreased rolling resistance is probably the most important performance factor effected by tire pressure. But on the rough surfaces on which some of us ride our road tandems increased pressure is not always faster. For those who ride MTB tandems this is true in spades. Three related factors; control, flotation, and traction, can be more important than rolling resistance and are often increased as tire pressure is decreased. If you wish to test this out take your bike down to the local elementary school, inflate your 35mm tires to the maximum pressure which you consider safe and take a ride through the sandbox. Now decrease your tire pressure by half and try it again. Another test? Find a trail or gravel bike path that has been chopped up by muddy horse hooves, frost heave, or gophers. Try the same tire pressure tests. Time yourself if you like. You may be surprised to discover that lower air pressure can make you faster. Those of us who race cyclocross discovered this long before my time. Our race tires are typically capable of pressures of 55 to 70 psi but we very seldom run them anywhere near those pressures. Indeed we have found that we often get better lap times with our tires inflated to less than half those numbers. The loss of speed on the asphalt portions of the course are more than made up for by the increased traction, control, and flotation on the rest of the course that we get from running our tires with 25 pounds of pressure.
    Brent
    Very true. I noticed when I was 12 that on level gravel I was faster on a Schwinn tank bike than I was on my 3-speed "English racer." But on asphalt I'd be out of sight of the Schwinns in just a few minutes. Flotation is huge. And I think that on loose surfaces, using lugged or treaded tires, more area presented to the surface creates more traction, unlike the situation on smooth surfaces.

    I should not have said "no matter what the surface." I meant no matter the condition of the ordinary hard surface. I think cobbles also require slightly reduced pressure. However on asphalt and concrete, including chipseal, my experience and test results are that more pressure is faster. It can be, however, more exhausting and thus slower in the long run, depending on how long that run is. Up to at least 400k on the average mix of asphalt road surfaces, more pressure seems to be faster.
    Last edited by Carbonfiberboy; 06-23-12 at 09:27 PM.

  25. #25
    just another gosling Carbonfiberboy's Avatar
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    Quote Originally Posted by Tom Spohn View Post
    Actually there are some tests with the same tires tested at different pressures. Unfortunately most of the tests are for tires that are appropriate for recumbants and trikes.
    http://www.microsofttranslator.com/B...l%2Fbandentest
    Thanks, cool. Not much question about those results.

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