Cycling and bicycle discussion forums. 
   Click here to join our community Log in to access your Control Panel  


Go Back   > >

Commuting Bicycle commuting is easier than you think, before you know it, you'll be hooked. Learn the tips, hints, equipment, safety requirements for safely riding your bike to work.

User Tag List

Reply
 
Thread Tools Search this Thread
Old 01-16-05, 08:20 PM   #1
madmanaenewman
Newbie
Thread Starter
 
Join Date: Jan 2005
Bikes:
Posts: 4
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
tire pressure of MTB rims with Slick tires

I've noticed from the archives that many people have put slick tires on their mountain bikes for road touring, but nobody seems to have addressed the critical area of tire pressure.
My rims, mavic x517s, are "rated" (they are not real clear here) in their web site as suited for pressures from 30 to 60 PSI. Thinner slick tires are usually intended to be inflated to about 80 to 100 PSI. In researching my rims prior to purchasing the bike they came with someone said he put slick tires on and it split the rims after a relatively short time, and was denied warrany replacement because he used the higher pressure tires.
Going to a 700 rim (ie, road bike intended for higher pressures) is out because the brakes would not align. Does anyone know if 26" rims exist that are actually rated for the higher pressures, or are people using lower tire pressures, or are people just tempting fate and hoping everthing works out. Admittedly, the rim on my bike is purposely built light for xc racing and perhaps a heavier rim would be stronger.
Any feedback would be greatly appreceiated.
madmanaenewman is offline   Reply With Quote
Old 01-17-05, 09:23 AM   #2
Mtn Mike
Super Biker
 
Mtn Mike's Avatar
 
Join Date: Nov 2002
Location: Spokane WA
Bikes: 2014 Curtlo, 2006 Serotta Coeur d’Acier, 2005 Independent Fabrication Steel Delux, 2003 Surly 1x1, 2003 Surly Cross Check, 1986 Schwin Worldsport SS commuter, 1980's Mongoose Supergoose
Posts: 1,183
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Mavic lists max pressure specs based on tire width for their rims. I couldn't find the 517, but the717 XC disc and all their other rims have pretty similar pressure specifications. The specs are listed at the bottom of that page.

edit:
After looking that chart over, I realized that I had been running my 517s with too high psi (65psi with 2.0 tires! ). Along with a worn braking surface, perhaps that's why they cracked!

Last edited by Mtn Mike; 01-17-05 at 09:34 AM.
Mtn Mike is offline   Reply With Quote
Old 01-17-05, 10:50 AM   #3
darkmother
Get the stick.
 
darkmother's Avatar
 
Join Date: Nov 2004
Location: Toronto, ON
Bikes: 12 Y.O. Litespeed MTB, IRO Jamie Roy fixie, Custom Habanero Ti 'Cross, No name SS MTB, Old school lugged steel track bike (soon)
Posts: 1,543
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
The rim rating is strongly dependent on what tire diameter you mount on the rim. For example, with a 2.1" mtb tire at 60 psi, the stress on the brake serface may very well be too high, especially as the brake surface wears down. With 1.25" slicks on the other hand, I doubt you will have any difficulty running within the rated tire pressure range-certainly more than 60 psi. FWIW, I have run 100 psi in 1.4" slicks on light MTB rims with no problems in the past.
darkmother is offline   Reply With Quote
Old 01-17-05, 05:31 PM   #4
notfred
Senior Member
 
Join Date: Aug 2004
Location: San Francisco, CA
Bikes:
Posts: 1,169
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
650c rims are the same size as 26" rims. You usually find them on Triathlon/time trial bikes, and they're designed for high pressure tires.
notfred is offline   Reply With Quote
Old 01-17-05, 07:38 PM   #5
Mtn Mike
Super Biker
 
Mtn Mike's Avatar
 
Join Date: Nov 2002
Location: Spokane WA
Bikes: 2014 Curtlo, 2006 Serotta Coeur d’Acier, 2005 Independent Fabrication Steel Delux, 2003 Surly 1x1, 2003 Surly Cross Check, 1986 Schwin Worldsport SS commuter, 1980's Mongoose Supergoose
Posts: 1,183
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
To end some of the confusion here, I copied this chart from Mavics website. Indeed, running a 1.0 tire should be safe on your rim.

TIRE SIZE MAXIMUM PRESSURE
inches bars psi
1.00 7.70 113.00
1.20 7.00 103.00
1.50 6.00 88.00
1.75 5.20 76.00
1.90 4.80 69.00
1.95 4.50 66.00
2.00 4.30 63.00
2.10 4.00 59.00
2.20 3.70 55.00
2.30 3.30 49.00
Mtn Mike is offline   Reply With Quote
Old 01-17-05, 08:39 PM   #6
glowingrod
Senior Member
 
Join Date: Oct 2004
Bikes:
Posts: 165
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
True, I ran 26 x 1.0 at 100psi with no problems for a long time, 26 x 1.25 at 90psi too. The biggest problem I had was getting 1.0 as this was before the internet(was widely used for buying) and my LBS had limitations on minimum ordering.
Another problem was Conti making 26 x 1.0 with weak sidewalls. If you kept them high you risked a blow out from a hummingbird wing tapping your tire on the side, if you kept them low a pebble would slap your rim if you rode over it
glowingrod is offline   Reply With Quote
Old 01-17-05, 09:59 PM   #7
d2create
Senior Member
 
d2create's Avatar
 
Join Date: Apr 2003
Location: Houston we have a problem
Bikes:
Posts: 2,914
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
i'm running my 1.5" Armadillo Nimbus at 80psi.
d2create is offline   Reply With Quote
Old 01-17-05, 10:53 PM   #8
madmanaenewman
Newbie
Thread Starter
 
Join Date: Jan 2005
Bikes:
Posts: 4
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Wow, great responses. I certainly appreciate all the help.
madmanaenewman is offline   Reply With Quote
Old 01-18-05, 12:50 AM   #9
Raiyn
I drink your MILKSHAKE
 
Raiyn's Avatar
 
Join Date: Jul 2002
Location: St. Petersburg, FL
Bikes: 2003 Specialized Rockhopper FSR Comp, 1999 Specialized Hardrock Comp FS, 1971 Schwinn Varsity
Posts: 15,061
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by d2create
i'm running my 1.5" Armadillo Nimbus at 80psi.
Ditto
__________________
Raiyn is offline   Reply With Quote
Old 01-18-05, 06:49 AM   #10
andygates
Just riding
 
andygates's Avatar
 
Join Date: Oct 2004
Location: Exeter, UK
Bikes: Cannondale Bad Boy / Mercian track / BOB trailer / Moulton recumbent project
Posts: 651
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Ratings schmatings. I'm running 26x1's at 100psi on my 618's, even with half the braking surface worn away by roadgrit. On a healthy rim the tyre will blow off before it'll damage the rim.
andygates is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -6. The time now is 08:32 PM.