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Low Crr tires for MTB rim?
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TOPIC: Low Crr tires for MTB rim?

Low Crr tires for MTB rim? 9 years, 4 months ago #22494

  • Nicko
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I need help with a very serious matter... here's the deal:
I will visit my wife's family in San Diego and a mid-90s 13+kg 21spd MTB is available. My brother-in-law rides a rides a nice $3k+ road bike with clinchers. By everyones account I *should* be much better than him so it's imperative that I don't get dropped up say, Couser Canyon. Can you say *competitive*...
Low Crr tires with nice, thin latex tubes could be the inconspicious help I need to maintain the family pecking order.

Does anyone know of hard or soft data for on-road rolling resistance for MTB (559mm) slick tires? Tire width doesn't matter.

Nic
'The purpose of computing is insight, not numbers', Hammings motto

Re: Low Crr tires for MTB rim? 9 years, 4 months ago #22501

  • kraig
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I don't have any data on low Crr MTB tires, but if family pecking order is at stake while going up Couser Canyon, heck, stop by the house and I'll let you borrow the pinarello hangin' on the wall - probably even throw in the fast wheels!

seriuosly - shoot me a PM, and if the timing is right, we might be able to make it work...

ooh, I think this might be some relevant data here:

http://www.legslarry.beerdrinkers.co.uk/tech/JL.htm

http://www.legslarry.beerdrinkers.co.uk/tech/GS.htm
-kraig

Re: Low Crr tires for MTB rim? 9 years, 4 months ago #22519

  • Nicko
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kraig wrote:
I don't have any data on low Crr MTB tires, but if family pecking order is at stake while going up Couser Canyon, heck, stop by the house and I'll let you borrow the pinarello hangin' on the wall - probably even throw in the fast wheels!

That's very generous, thanks!
A road bike would however ruin my dream scenario - me dropping my brother-in-law while he hears the ancient Grip-Shifts and sees the bobbing front fork up the road and goes "WTF?". Total alpha-male domination

I think I have seen that list before - seems hard to identify tires you can buy today. Conti Avenue, Nokian Ultra Tour and Specialized Turbo S are no more (?).
I think there is a Schwalbe Stelvio for 559mm rim - could fit the bill.
'The purpose of computing is insight, not numbers', Hammings motto

Re: Low Crr tires for MTB rim? 9 years, 4 months ago #22523

  • Ron Ruff
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Nicko wrote:
A road bike would however ruin my dream scenario - me dropping my brother-in-law while he hears the ancient Grip-Shifts and sees the bobbing front fork up the road and goes "WTF?". Total alpha-male domination


In that case run knobbies... and put a rack on with a cooler of beer...

I recently bought some Forte 1.25" slicks for my wife's bike and they felt very supple... cost only $6 each too...

Re: Low Crr tires for MTB rim? 9 years, 4 months ago #22549

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Ron Ruff wrote:

In that case run knobbies... and put a rack on with a cooler of beer...

I recently bought some Forte 1.25" slicks for my wife's bike and they felt very supple... cost only $6 each too...

The magnitude of satisfaction from dropping him with knobbies won't top the fear of the opposite...
plus he can't appreciate the performance difference between different rubbers.
I'll try the Forte's and some 700c latex tubes cut down to 26". Substituting some of the regular 15-25min intervals for VO2max bouts won't hurt either.
'The purpose of computing is insight, not numbers', Hammings motto

Re: Low Crr tires for MTB rim? 9 years, 4 months ago #22550

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There are those Michelin 26" slicks that, I believe, are exactly the same thing as Pro2Race but a different size/diameter:

http://two-wheels.michelin.com/2w/front ... 49&lang=EN
These are sold in the US too:
http://biketiresdirect.com/productdetail.asp?p=MIRXC

and this would be a reasonable price in USD I think. They come in 1.4" - will take 100-110 PSI, yet the rim strength and rim tape quality become an issue at higher pressures - that would be a problem with any high pressure slick, as maybe neither MTB rims nor MTB rim tapes are designed with such pressures in mind - just a speculation.

Also there's the Tioga City Slicker - perhaps not as good as the Michelin Crr-wise, but comes in 1" (which I find useful, since I often use 650c front forks on MTB frames for city commuting projects - people like the funky steering - and a 1.4" tire will not go through a 650c road fork) The Tioga City Slickers will also take at least 100 PSI if your rims are good for that:



There is also a Continental tire:

http://biketiresdirect.com/productdetail.asp?p=COGPR
although I think this price is ridiculous, noone else seems to have this particular kind.

Finaly there's a Rubino Pro based Vittoria 26x1.5" tire, which is factory rated 100-130 PSI and should be relatively OK
in terms of Crr - again that's a somewhat educated guess on my behalf:

http://www.bikesomewhere.com/bikesomewh ... /25084?g=1
http://www.vittoria.com/index.php?optio ... Itemid=116

If fork clearance is not a limiting factor, I'd go with the Michelin. If a 23mm Michelin Pro2Race rolls better than a 20mm one, then a 34-35mm Michelin Pro2Race will roll even better, uh? OK, there is a bit more material in the MTB version, but it's got to be in the same ball park as the P2R.

Hope this helps.

Nick.

Re: Low Crr tires for MTB rim? 9 years, 4 months ago #22551

  • renegade027
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For 1.25" MTB tires and certainly for 1" ones, you could definitely cut down 700c latex tube and have no worries.

For anything bigger than 1.25" you will need a bigger size inner tube.The 18-23 mm latex (and butyl) ones fail immediately in a, say, 1.4" Michelin tire.

This one will work perfect with 1.4-1.5" tires:

http://www.bikesomewhere.com/bikesomewh ... /19211?g=1

Don't know if it will reduce the RR much as even if made from latex it's like 130g.

Re: Low Crr tires for MTB rim? 9 years, 4 months ago #22560

  • pritchet74
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Search the archives here on BTR - I know that a few years ago (2005?) jheycke did some field testing for MTB tires for Crr. I forget the tire that was the best, but I promptly purchased 2 of them because they had just been discontinued. I still have the pair in their original boxes sitting on my work bench though since I sold my MTB last year. Guess I should get rid of them!

Re: Low Crr tires for MTB rim? 8 years, 11 months ago #23889

  • Nicko
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renegade027 wrote:
There are those Michelin 26" slicks that, I believe, are exactly the same thing as Pro2Race but a different size/diameter:

http://two-wheels.michelin.com/2w/front ... 49&lang=EN
These are sold in the US too:
http://biketiresdirect.com/productdetail.asp?p=MIRXC

and this would be a reasonable price in USD I think. They come in 1.4" - will take 100-110 PSI, yet the rim strength and rim tape quality become an issue at higher pressures - that would be a problem with any high pressure slick, as maybe neither MTB rims nor MTB rim tapes are designed with such pressures in mind - just a speculation.



Update:
I got a pair of Michelin 26x1.4 Grey/Black XCR Road with 66 tpi, folding bead at 335 grams.
Front tire has a 1" generic butyl tube.
Rear tire has an 18-20mm Michelin latex tube (thats right!) cut down to fit the MTB circumference according to this instruction [url:20bxwpga]biketechreview.com/forum/viewtopic.php?f=1&t=2230[/url]
Works perfect, I have used the same skinny latex tube in a 35mm Ritchey Speedmax CX tire all fall, without any punctures

Anyway, went up Couser Canyon (as made famous by KW ) twice today, alas alone, but the tires do "feel" fast at 5bar/70psi. Field testing results will come later
'The purpose of computing is insight, not numbers', Hammings motto

Re: Low Crr tires for MTB rim? 8 years, 11 months ago #23891

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Nicko wrote:


Anyway, went up Couser Canyon (as made famous by KW ) twice today, alas alone, but the tires do "feel" fast at 5bar/70psi.


We must have just missed each other, then - I went as hard as I could up that sucker today at around 9:30 AM - didn't see anybody out there either!
-kraig

Re: Low Crr tires for MTB rim? 8 years, 11 months ago #23898

  • Nicko
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kraig wrote:
Nicko wrote:


Anyway, went up Couser Canyon (as made famous by KW ) twice today, alas alone, but the tires do "feel" fast at 5bar/70psi.


We must have just missed each other, then - I went as hard as I could up that sucker today at around 9:30 AM - didn't see anybody out there either!

Yup, I was there around 11-12AM. Maxed out my HR second round up
I seem to remember you spending ~17mins there - that must be starting from the 76, right? The actual climb took me 14:54 at 327W, PB for the duration. It was quite inspiring to be on "holy ground"
'The purpose of computing is insight, not numbers', Hammings motto

Re: Low Crr tires for MTB rim? 8 years, 11 months ago #23901

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Nicko wrote:

Yup, I was there around 11-12AM. Maxed out my HR second round up
I seem to remember you spending ~17mins there - that must be starting from the 76, right? The actual climb took me 14:54 at 327W, PB for the duration. It was quite inspiring to be on "holy ground"


Not quite from the 76, maybe 300ish meters from that intersection at the little road sign just after crossing the san luis rey river/wash "bridge". total distance is something like 6.1 km or so.

That's a lot of power going up that sucker! Nice time - pretty crazy to think how fast you would go using a road bike rather than a mountain bike!
-kraig

Re: Low Crr tires for MTB rim? 8 years, 3 months ago #25251

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Update (forgot about it ):
- As noted before, a pair of Michelin 26x1.4 Grey/Black XCR Road with 66 tpi, folding bead at 335 grams, front tire had a 1" generic butyl tube, rear tire had a 18-20mm Michelin latex tube.
- Typical warm weather XC outfit.
- Total mass: 95kg (MTB alone was 13kg )
- I'm 180cm
- Venue: good asphalt, ~750m "U-ramp" out&back loop in residential area. ~0.2m/s head/tailwind.

Work per lap regression a la Haile yields:
Crr = 0.59 +/- 0.02
CdA = 0.394 +/- 0.006

I would out-roll my brother-in-law with his Specialized Roubaix shod with Armadillos+extra flat-resistant butyl tubes
I had to feather the brakes so he wouldn't suspect anything
Anyway, family pecking order is set for a while now...
'The purpose of computing is insight, not numbers', Hammings motto

Re: Low Crr tires for MTB rim? 8 years, 3 months ago #25253

  • CyclingEngr
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Nice job! With him riding armadillos you could have gone for the knobbies!

Re: Low Crr tires for MTB rim? 8 years, 3 months ago #25262

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I did do a number of tests. At the time, the best I found was the Kenda Kozmik lite. Curiously, the Kozmik lite 2 was slower. You also had to be careful which specific tire you used, because some Kozmik lites had flat spots.

Those tires, along with Mich. latex tubes helped me win the Overall Mt. title of the Mt. Ashland hill 3 years. In '05, the 2nd place guy (Geoff Huber) came in 4 minutes later, despite averaging ~10 watts more power. Equipment actually does matter sometimes.

I did test some really narrow slicks - the Continental 1.125" -- curiously they were almost as slow as the knobbies. The michelins I tested were also disappointingly slow.

Re: Low Crr tires for MTB rim? 8 years, 3 months ago #25264

  • Ron Ruff
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Jens!... where have you been?

Re: Low Crr tires for MTB rim? 8 years, 3 months ago #25265

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I'm still riding a bit -- mostly in the garage on the computrainer. I stopped racing because I was concerned about it distracting too much of my attention from my kids. In any case, with a preschooler and the weekly colds that he brings, what's the point anyway.....

I may consider resuming in 2011, when everyone's in school full-time (and I can race 50s). Though frankly, it's a little disheartening that I don't have to go to national or even state level to get smoked. There are 4 or 5 right in my neighborhood (like Novitzky) who can do it.....

Re: Low Crr tires for MTB rim? 8 years, 3 months ago #25271

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jens wrote:
I'm still riding a bit --


Good to hear from you Jens!

Keep it fun - it's just bike stuff, eh?
-kraig

Re: Low Crr tires for MTB rim? 8 years, 3 months ago #25272

  • kraig
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Nicko wrote:

Work per lap regression a la Haile yields:
Crr = 0.59 +/- 0.02
CdA = 0.394 +/- 0.006




Thanks for the update, Nicko!

Good stuff!


If I might ask, how are you estimating your +/- value while using the work per lap method?
-kraig

Re: Low Crr tires for MTB rim? 8 years, 3 months ago #25285

  • Ron Ruff
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jens wrote:
I may consider resuming in 2011, when everyone's in school full-time (and I can race 50s). Though frankly, it's a little disheartening that I don't have to go to national or even state level to get smoked. There are 4 or 5 right in my neighborhood (like Novitzky) who can do it.....


You just need to move to an easier neighborhood! You'd do fine around here.

Re: Low Crr tires for MTB rim? 8 years, 3 months ago #25288

  • JV
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jens wrote:
Though frankly, it's a little disheartening that I don't have to go to national or even state level to get smoked. There are 4 or 5 right in my neighborhood (like Novitzky) who can do it.....


The other way to frame that is that you must live in a great place to race bikes! I find the process of succeeding at something much more meaningful when it's kinda challenging (if it were easy, everyone would do it). Also, you don't have to waste time & money traveling...you can just race locally.

Nice to see you still peruse the internets bike forums!

Re: Low Crr tires for MTB rim? 8 years, 2 months ago #25470

  • Nicko
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kraig wrote:
Nicko wrote:

Work per lap regression a la Haile yields:
Crr = 0.59 +/- 0.02
CdA = 0.394 +/- 0.006




Thanks for the update, Nicko!

Good stuff!


If I might ask, how are you estimating your +/- value while using the work per lap method?

Sorry, meant to answer this but I forgot

The +/- values are what the (extended) Excel function LINEST spits back when estimating a "y=mx+b" line to X/Y pairs. It's the SE's for the estimations of m and b.

This field test consisted of 18 laps, 9 slow and 9 fast, so I got 18 pairs of "distance averaged dynamic pressures" vs "distance averaged forces" after some KE cleanup. All credit to A Haile.

The data pairs, without the SE's:[attachment=0:1v3fps5w]<!-- ia0 WPL.PNG<!-- ia0 [/attachment:1v3fps5w]
Not really sure how to interpret the SE's of the estimates of a line. SE's of "direct measurements" I get :?
'The purpose of computing is insight, not numbers', Hammings motto

Re: Low Crr tires for MTB rim? 8 years, 2 months ago #25486

  • kraig
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ooh, yeah, the LINEST thing is a bit sketchy to me...which is why I tried to quantify the variability of things with a caveman based bootstrapping technique.

good stuff, though, and glad to see you doing a significant number of laps for a given configuration. I fear that most people aren't this diligent and try to make claims on data sets with a limited number of laps.

thanks for sharing!
-kraig

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