max. pressure for rims?

Do your Mavic rims have a note somewhere saying they'll take exactly 146psi before exploding and sending your nose to a grinding on asphalt death? 146 exactly?

I wonder if they took into account the lack of calibration across all the guages on track pumps.

Wouldn't tires be the weak link here? Sensible pressures don't cause tires to explode off the rims because of over inflation.

Quoted post said:

Originally Posted by swampy1970 [IMG]/img/forum/go_quote.gif[/IMG]

Do your Mavic rims have a note somewhere saying they'll take exactly 146psi before exploding and sending your nose to a grinding on asphalt death? 146 exactly?

I wonder if they took into account the lack of calibration across all the guages on track pumps.

thats what I was thinking to actually..... I usually put the pressure at 5psi below the limit

Mavic says 138 psi is the pressure limit for their OP rims running 23 mm tires. A new rim can probably take a lot more than this, but when you combine rim sidewall wear, as well as the variations in tires and pressure gauges, and road bumps, the safe limit comes down a lot.

mavic.comtirepressurechart eng.pdfOpen ↗

Quoted post said:

Originally Posted by finnrambo [IMG]/img/forum/go_quote.gif[/IMG]
..... I usually put the pressure at 5psi below the limit...

Why do you pump your tires up so high?

IIRC you're a very light rider. From both a comfort and performance standpoint it's not a great idea to pump your tires as hard as they'll go unless you happen to be riding on extremely smooth surfaces like high quality wooden velodromes. On real world roads you reach a point where the extra tire pressure just slows you down even though those rock hard tires feel fast by transferring every little vibration. This is pretty easy to measure with a power meter equipped bike but here's a good piece discussing rolling resistance and the downside of excessive tire pressures: http://www.slowtwitch.com/Tech/What_s_in_a_tube__1034.html

FWIW, at 150 pounds I rarely get anywhere near the max pressure ratings for the tires or the rims if you weigh less you'd want less tire pressure not more for best comfort, best cornering, and best speed out of your tires.

-Dave

Quoted post said:

Originally Posted by swampy1970 [IMG]/img/forum/go_quote.gif[/IMG]

Do your Mavic rims have a note somewhere saying they'll take exactly 146psi before exploding and sending your nose to a grinding on asphalt death? 146 exactly?

I wonder if they took into account the lack of calibration across all the guages on track pumps.

146psi is not a nice round number because most of the world measures pressure in metric units of bar (approximately = atmospheres) or kilopascals (kPa) (1kPa = 0.01bar). 146psi just happens to be 10bar rounded to the nearest higher psi. psi are predominantly found in countries which still use imperial units or recently (in the last 40 years) left them behind.

You can bet that there will also be a significant margin of safety to account somewhat for user stupidity (though this can never really be eliminated).

Research shows (and has shown for some time) that higher pressures do NOT lead to reduced rolling resistance. For every combination of rider, tyre size, tyre type, and road surface there will be an ideal pressure (above and below which rolling resistance will increase). For the usual 23mm offerings on most roads this is usually around the range of 6.5 - 8 bar (about 90-115psi).

hi, not a guarantee here, but my hubby used to put 160 psi into clincher continental supersonics on mavic equipes. never had any blow outs or rim fractures

Quoted post said:

Originally Posted by etapedutour [IMG]/img/forum/go_quote.gif[/IMG]

hi, not a guarantee here, but my hubby used to put 160 psi into clincher continental supersonics on mavic equipes. never had any blow outs or rim fractures

Sounds like a candidate for solid rubber tires... [IMG]/img/vbsmilies/smilies/wink.gif[/IMG]

Quoted post said:

Originally Posted by daveryanwyoming [IMG]/img/forum/go_quote.gif[/IMG]

Why do you pump your tires up so high?

IIRC you're a very light rider. From both a comfort and performance standpoint it's not a great idea to pump your tires as hard as they'll go unless you happen to be riding on extremely smooth surfaces like high quality wooden velodromes. On real world roads you reach a point where the extra tire pressure just slows you down even though those rock hard tires feel fast by transferring every little vibration. This is pretty easy to measure with a power meter equipped bike but here's a good piece discussing rolling resistance and the downside of excessive tire pressures: http://www.slowtwitch.com/Tech/What_s_in_a_tube__1034.html

FWIW, at 150 pounds I rarely get anywhere near the max pressure ratings for the tires or the rims if you weigh less you'd want less tire pressure not more for best comfort, best cornering, and best speed out of your tires.

-Dave

so for 115pounds I should go 95-100psi? speaking of velodromes........ I should probably bring my 220psi down to 180psi, not the smoothest velodrome in the world, maybe bring it down more? (the velodrome is 25+ years old)

Yep, both would be good ideas. If you follow the advice by Tom A, in the attached link a good approach is to inflate your tires till you feel the road buzz and they 'feel' fast....then back them off by a few psi so they actually are fast.

-Dave

Quoted post said:

Originally Posted by daveryanwyoming [IMG]/img/forum/go_quote.gif[/IMG]

Yep, both would be good ideas. If you follow the advice by Tom A, in the attached link a good approach is to inflate your tires till you feel the road buzz and they 'feel' fast....then back them off by a few psi so they actually are fast.

-Dave

thanks Dave!

actually it happens that tires cause rims to explode, rims being the weakest link... but yeah it doesn't happen that often and usually on cheaper bikes (like the chen shin road bike you can buy at zellers.

Quoted post said:

Originally Posted by Olivier L [IMG]/img/forum/go_quote.gif[/IMG]

actually it happens that tires cause rims to explode, rims being the weakest link... but yeah it doesn't happen that often and usually on cheaper bikes (like the chen shin road bike you can buy at zellers.

You'll likely find that the steel rims on cheaper bikes will be a little more forgiving that the lightweight aluminum rims - but they'll also weigh a fair bit more and have fun when it rains stopping on steel rims with a nice chrome surface.

Hello All, this is my first post.

I need help in choosing the optimum tire/wheel setup for my training. I intend to road race...eventually.
I'm 6'6 and weigh 260 lbs., and need a strong high pressure tire/wheel combination. I know tufo has a tubular clincher tire that takes 220 lbs., are there rims to support that? Any higher pressure/stronger tires? Suggestions?

Thank you for any comments you can provide.

Hmmm...why would that question come up? Isn't the important factor the max rated pressure on the sidewall? If a tire manufacture says it's tire can go up to 125 psi (for example only) then a rim can take that pressure without breaking a sweat! If you are trying to blow a tire up for fun and want to know how much PSI the rim can handle before you attempt such a feat, then again no fear because rims are designed to take on very high amounts of PSI so the tire would blow first before the rim...this is a built in safety protocol for rims. I once had 240 pounds of PSI in a tire mounted to a rim with no problem with either actually...I was not riding on it in case you were wondering, it was an experiment to long and off subject for this post.