Guest 1913 T Posted July 26, 2009 Share Posted July 26, 2009 Hello I keep having a problem with my valve stems on my rear tires shearing off the tube , resulting in a flat tire. I have been purchasing the 30"x3-1/2" with the metal stem. I dont know if I am over inflating the tires or underinflating them I have been putting 45lbs of air in the tires. Are my brakes to tight and are causing the tires to grip the road so well that they spin a little on the rim causing the stem to be sheared off the tube? I have had the stem sheared off 3 times in about 2 years. I completed the 2009 Brass and gas tour with no problems and I was on the brakes a lot going down a lot of hills. Any thoughts would be greatThanks Link to comment Share on other sites More sharing options...
oldford Posted July 26, 2009 Share Posted July 26, 2009 You need more air in the tube. 3 1/2 clinchers should have 60 lbs. of pressure in them. With low air, the tube creeps in the tire and cuts off the stem. Frank Link to comment Share on other sites More sharing options...
Terry Bond Posted July 27, 2009 Share Posted July 27, 2009 Agree with Frank - I usually keep 60-65lbs pressure in them and have not had any probs. That air pressure is what keeps the clincher on the rim.Terry Link to comment Share on other sites More sharing options...
Layden B Posted July 28, 2009 Share Posted July 28, 2009 When using metal stems, be sure you have the proper bridge washer installed. This "bridges" over the felloe hole and keeps the tube air pressure from pushing the stem out the hole and ripping it off the tube. Link to comment Share on other sites More sharing options...
Guest 1913 T Posted July 29, 2009 Share Posted July 29, 2009 Thanks for the information guys , I just received my new tubes and it came with the metal bridge and two lock nuts. I assume that you slip the metal bridge over the metal stem and lock it on with one nut and then assemble the tire and tube and place the second nut on the outside of the rim on the metal stem. Thanks Again Mike Link to comment Share on other sites More sharing options...
Guest tmodelman Posted July 30, 2009 Share Posted July 30, 2009 The bridge washer and nut keep the metal stem tube from moving. Keep the clincher tire pressure at least 60psi, not less. You can use more up to 70psi if you want.And the use of flaps does help not only in mounting to keep from pinching the tube, but keeps the thin tube from wear at the clincher bead joint, the beads fit into the rim, but leave a gap in the middle that can wear the tube prematurely. Link to comment Share on other sites More sharing options...
Guest 1913 T Posted July 30, 2009 Share Posted July 30, 2009 Thanks again everybody!!A picture is worth a thousand words! Link to comment Share on other sites More sharing options...
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