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#11
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Blowing tube descending
On Monday, April 3, 2017 at 5:49:53 PM UTC-7, wrote:
In the flatlands we never worry about this stuff but still seems unreal you could blow a tire by overheating the rims. How long does the descent need to be and braking? I have taken a mile 5-9% grade down and had to brake in places but does it mean you simply ride the brake continuously to get too much heat. Have any here had this happen due to heat not poor install or other tire blows. Deacon Mark We have a lot of hills in the San Francisco bay area and I can't remember ever getting a flat from riding the brakes including one mile long 18% grade so I think that your blowout was a fluke from either a pinch during installation which made a weak spot in the tube or a manufacturing error. I have found these in the cheap tubes from Performance Bicycle. You can inflate the tire and a half hour later you can have it explode. Or you can come out the next day for a ride and the tire will be flat. Continental tubes don't do this but they are expensive. |
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#12
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Blowing tube descending
On Thursday, April 6, 2017 at 1:55:29 PM UTC-7, wrote:
On Monday, April 3, 2017 at 5:49:53 PM UTC-7, wrote: In the flatlands we never worry about this stuff but still seems unreal you could blow a tire by overheating the rims. How long does the descent need to be and braking? I have taken a mile 5-9% grade down and had to brake in places but does it mean you simply ride the brake continuously to get too much heat. Have any here had this happen due to heat not poor install or other tire blows. Deacon Mark We have a lot of hills in the San Francisco bay area and I can't remember ever getting a flat from riding the brakes including one mile long 18% grade so I think that your blowout was a fluke from either a pinch during installation which made a weak spot in the tube or a manufacturing error. I have found these in the cheap tubes from Performance Bicycle. You can inflate the tire and a half hour later you can have it explode. Or you can come out the next day for a ride and the tire will be flat. Continental tubes don't do this but they are expensive. At Bikekit Pro the Continental tubes for a 23 mm tire are $9 apiece. Though at that price maybe they just give you the drive to be extra careful when mounting. |
#13
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Blowing tube descending
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#14
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Blowing tube descending
wrote:
In the flatlands we never worry about this stuff but still seems unreal you could blow a tire by overheating the rims. How long does the descent need to be and braking? I have taken a mile 5-9% grade down and had to brake in places but does it mean you simply ride the brake continuously to get too much heat. Have any here had this happen due to heat not poor install or other tire blows. Deacon Mark myself no, I grew up in area with both short and very steep and longer shallower climbs though I'm more MTB than roadie. longest decent i've done is just shy of 22 miles I've done it few times now, not thus far had problems with the rim warming much. I'm sure some can get into trouble one only has to go on charity/sportives etc to see that riding ablity covers quite a range! Roger Merriman |
#15
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Blowing tube descending
I beg to disagree. On one of my favorite rides near Placerville, CA, going southeast on Buck's Bar Road, you descend 670 feet to the Cosumnes River in less than a mile. On a hot day, that will heat up my Mavic Open Sport rims so the heat is conducted up the metal valve stem and the tube fails at its base. It always happens just as you start the ascent from the Cosumnes gorge to the town of Somerset, so it is rather discouraging. Therefore I've made it a habit of stopping halfway down the descent at a Cosumnes River overlook to let my rims cool.
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#16
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Blowing tube descending
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#17
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Blowing tube descending
Duane wrote: Disagree with what? Maybe copy a bit of what you're replying to...
Sorry, Duane, but I thought there was a clear consensus in the foregoing posts that blowouts from rim heat due to descending don't really happen anymore. |
#18
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Blowing tube descending
On Thursday, April 20, 2017 at 6:16:10 AM UTC-7, wrote:
Duane wrote: Disagree with what? Maybe copy a bit of what you're replying to... Sorry, Duane, but I thought there was a clear consensus in the foregoing posts that blowouts from rim heat due to descending don't really happen anymore. Can you suggest why blowing out a tube would be worse than pushing a worn-out disk pad out the side of the actuator and ending up with no brakes at all? Disks seem to be the great fix but after my using them they have a lot of weaknesses. They are generally too strong and far too easy to lock a wheel, especially off-road. The pads are far too shallow and wear out very rapidly.. Talking about ceramic pads is a bit funny to me since instead of wearing the pad you then wear the disk. In any case you can rapidly lose the full length that the actuator will move. A disk brake is all about leverage. So the total movement of the pad is very slight so that the implied lever arm can be long. So it doesn't take much wear anywhere in the system to lose total brakes. There are limits to everything. If you are blowing tubes because of overheating rims you are going too fast. Or you are braking too much. I can't say I'm an expert off-road but I can get along. I've had my share of crashes and as a rule they have been so damn scary that I've always had time to situate my body so that I don't land on my head. That's a hell of a lot more than I can say about road bikes where you are generally going so fast and so close to the ground that there's no time to think and head injuries are fairly common. So as I get older I am taking more and more of an upright posture not because I have trouble getting down on the drops but because it gives me more options in a crash. I've actually seen MTB riders step off of a bike in a crash without actually falling off at pretty high speeds. Don't try this at home. |
#19
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Blowing tube descending
On Thursday, April 20, 2017 at 6:40:01 AM UTC-7, wrote:
On Thursday, April 20, 2017 at 6:16:10 AM UTC-7, wrote: Duane wrote: Disagree with what? Maybe copy a bit of what you're replying to... Sorry, Duane, but I thought there was a clear consensus in the foregoing posts that blowouts from rim heat due to descending don't really happen anymore. Can you suggest why blowing out a tube would be worse than pushing a worn-out disk pad out the side of the actuator and ending up with no brakes at all? Disks seem to be the great fix but after my using them they have a lot of weaknesses. They are generally too strong and far too easy to lock a wheel, especially off-road. The pads are far too shallow and wear out very rapidly. Talking about ceramic pads is a bit funny to me since instead of wearing the pad you then wear the disk. In any case you can rapidly lose the full length that the actuator will move. A disk brake is all about leverage. So the total movement of the pad is very slight so that the implied lever arm can be long. So it doesn't take much wear anywhere in the system to lose total brakes. There are limits to everything. If you are blowing tubes because of overheating rims you are going too fast. Or you are braking too much. I guess I haven't had any problems with discs that would disqualify them from use. I have had problems with rims over-heating -- although only on a tandem or with sew-ups. I was flying down Page Mill on a hot summer day 40 years ago with squirming sew-ups, and I was so worried about braking that when a squirrel ran out in front of me, I just ran over it. Anyway, if you're on a long, steep, twisting descent, probably the only thing you can do is stop every so often to let your rims cool and maybe even your discs. Well, you could avoid the descent, but what fun is that. For Retrogrouch: be happy you're not coming up the other side of that climb.. It works out to an average 12%. -- Jay Beattie |
#20
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Blowing tube descending
On Thursday, April 20, 2017 at 7:15:05 AM UTC-7, jbeattie wrote:
On Thursday, April 20, 2017 at 6:40:01 AM UTC-7, wrote: On Thursday, April 20, 2017 at 6:16:10 AM UTC-7, wrote: Duane wrote: Disagree with what? Maybe copy a bit of what you're replying to... Sorry, Duane, but I thought there was a clear consensus in the foregoing posts that blowouts from rim heat due to descending don't really happen anymore. Can you suggest why blowing out a tube would be worse than pushing a worn-out disk pad out the side of the actuator and ending up with no brakes at all? Disks seem to be the great fix but after my using them they have a lot of weaknesses. They are generally too strong and far too easy to lock a wheel, especially off-road. The pads are far too shallow and wear out very rapidly. Talking about ceramic pads is a bit funny to me since instead of wearing the pad you then wear the disk. In any case you can rapidly lose the full length that the actuator will move. A disk brake is all about leverage. So the total movement of the pad is very slight so that the implied lever arm can be long. So it doesn't take much wear anywhere in the system to lose total brakes. There are limits to everything. If you are blowing tubes because of overheating rims you are going too fast. Or you are braking too much. I guess I haven't had any problems with discs that would disqualify them from use. I have had problems with rims over-heating -- although only on a tandem or with sew-ups. I was flying down Page Mill on a hot summer day 40 years ago with squirming sew-ups, and I was so worried about braking that when a squirrel ran out in front of me, I just ran over it. Anyway, if you're on a long, steep, twisting descent, probably the only thing you can do is stop every so often to let your rims cool and maybe even your discs. Well, you could avoid the descent, but what fun is that. For Retrogrouch: be happy you're not coming up the other side of that climb. It works out to an average 12%. -- Jay Beattie A couple of years ago when the Tour of California was doing several stages in the area I was flying down Page Mill with a couple of friends and coming up was what looked like the Stanford group with perhaps 50 in the group FLYING up and taking up the entire lane. I don't remember any of the climbs in that area being particularly troublesome. On one of them I was with a large group and the front half disappeared and a city crew stopped my group. They were cutting a tree down and it took about a half hour. You should have heard the other group when we got to the top. They thought we had forgotten how to climb. |
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