Blowing tube descending

On 20/04/2017 9:16 AM, 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.


No problem. Just that threads around here tend to wander and I don't
keep old posts.

If that was the consensus, then I agree with you that it can still
happen. Although I also know that if you can let the brakes go for a
bit the fast descent cools the rims as well.

I don't have disk brakes on my bike but I can see why some people do.
Jay rides a lot in the rain in a very hilly area for example...

Duane wrote: "If you are blowing tubes because of overheating rims you are going too fast. Or you are braking too much."

Yes, I probably brake a lot and descend slower than a lot of other riders. Part of that is because I'm an old guy, but you know what? I haven't fallen off the bike in a long time!

Jay wrote "For Retrogrouch: be happy you're not coming up the other side of that climb. It works out to an average 12%."

Yes, I have done that climb a number of times. When I was younger I could do it without stopping, but now I really hate it because I have to get off the dam*ed bike and rest at least once. I don't like to have to do that! People tell me I should get a lower gear, but I dunno. My low is 35 inches, and I think that the day that I am too weak to push that gear will probably be the day I quit riding.

On 20/04/2017 11:45 AM, wrote:
Duane wrote: "If you are blowing tubes because of overheating rims you are going too fast. Or you are braking too much."

Yes, I probably brake a lot and descend slower than a lot of other riders. Part of that is because I'm an old guy, but you know what? I haven't fallen off the bike in a long time!

Jay wrote "For Retrogrouch: be happy you're not coming up the other side of that climb. It works out to an average 12%."

Yes, I have done that climb a number of times. When I was younger I could do it without stopping, but now I really hate it because I have to get off the dam*ed bike and rest at least once. I don't like to have to do that! People tell me I should get a lower gear, but I dunno. My low is 35 inches, and I think that the day that I am too weak to push that gear will probably be the day I quit riding.


Thanks for the quote but I didn't say:
"If you are blowing tubes because of overheating rims you are going too
fast. Or you are braking too much."

I can't really parse that. The people that I've seen blowing tubes
because of overheating it was generally caused by them wanting to not go
too fast for conditions.

The situation that I described when my rims were overheating, I had a
choice to brake enough to slow in the curves, go off the mountain or
stop and walk. I was able to manage without walking or blowing a tube
but the smell of the rubber burning scared the hell out of me. g

On 4/20/2017 10:15 AM, jbeattie wrote:
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.

PETA agents will be pounding on your door soon.

I'm proud to say that no animals were harmed during my two bike rides
yesterday.

--
- Frank Krygowski

On 4/20/2017 12:06 PM, Duane wrote:
On 20/04/2017 11:45 AM, wrote:
Duane wrote: "If you are blowing tubes because of overheating rims you
are going too fast. Or you are braking too much."

Yes, I probably brake a lot and descend slower than a lot of other
riders. Part of that is because I'm an old guy, but you know what? I
haven't fallen off the bike in a long time!

Jay wrote "For Retrogrouch: be happy you're not coming up the other
side of that climb. It works out to an average 12%."

Yes, I have done that climb a number of times. When I was younger I
could do it without stopping, but now I really hate it because I have
to get off the dam*ed bike and rest at least once. I don't like to
have to do that! People tell me I should get a lower gear, but I
dunno. My low is 35 inches, and I think that the day that I am too
weak to push that gear will probably be the day I quit riding.


Thanks for the quote but I didn't say:
"If you are blowing tubes because of overheating rims you are going too
fast. Or you are braking too much."

I can't really parse that. The people that I've seen blowing tubes
because of overheating it was generally caused by them wanting to not go
too fast for conditions.

The situation that I described when my rims were overheating, I had a
choice to brake enough to slow in the curves, go off the mountain or
stop and walk. I was able to manage without walking or blowing a tube
but the smell of the rubber burning scared the hell out of me. g

Again, according to one technical article from long ago, for a lot of
grades, maximum rim temperature occurs when you try to hold the speed to
about 30 mph. Descending slower inputs energy into the system at a
slower rate. Descending faster allows aerodynamic drag to take some of
the load.

Unfortunately, 30 mph is about the speed a lot of riders choose for fast
downhills.


--
- Frank Krygowski

On Thu, 20 Apr 2017 08:45:27 -0700 (PDT),
wrote:

My low is 35 inches, an=
d I think that the day that I am too weak to push that gear will probably b=
e the day I quit riding.

When I had very low gears put on my first real bike, I said to the
mechanic, "I'll be back to get higher gears after when I've built up
some muscle." He answered "No, you will climb steeper hills."

And I'm still riding those gears. But if I make a habit of riding on
150 W, which has a very steep dip with a divided highway in the
valley, I may ask the Trailhouse whether they can install a bigger
inside cog -- I know that I'm already using the smallest-possible
inner chainwheel.

On the other hand, just after I cross US 30, there's a convenient
driveway where I cam pull off and change into walking shoes, and it's
only two miles from there to city streets where I'd want walking shoes
anyway. And all downhill, once I've walked to the top.

Meanwhile, I'm walking down every staircase I can, and if nobody is
looking, I'll walk up backward.

I've learned a new trick for climbing hills when seventy-six: when I
see a hill I'm not sure I can climb, I sit down at the top of the
previous hill and rest for five minutes by the clock. Then I pedal as
fast as I can coming down, and find the climb fairly easy.

--
joy beeson at comcast dot net
http://wlweather.net/PAGESEW/
The above message is a Usenet post.
I don't recall having given anyone permission to use it on a Web site.

On Thu, 20 Apr 2017 16:04:41 -0400, Frank Krygowski
wrote:

On 4/20/2017 12:06 PM, Duane wrote:
On 20/04/2017 11:45 AM, wrote:
Duane wrote: "If you are blowing tubes because of overheating rims you
are going too fast. Or you are braking too much."

Yes, I probably brake a lot and descend slower than a lot of other
riders. Part of that is because I'm an old guy, but you know what? I
haven't fallen off the bike in a long time!

Jay wrote "For Retrogrouch: be happy you're not coming up the other
side of that climb. It works out to an average 12%."

Yes, I have done that climb a number of times. When I was younger I
could do it without stopping, but now I really hate it because I have
to get off the dam*ed bike and rest at least once. I don't like to
have to do that! People tell me I should get a lower gear, but I
dunno. My low is 35 inches, and I think that the day that I am too
weak to push that gear will probably be the day I quit riding.


Thanks for the quote but I didn't say:
"If you are blowing tubes because of overheating rims you are going too
fast. Or you are braking too much."

I can't really parse that. The people that I've seen blowing tubes
because of overheating it was generally caused by them wanting to not go
too fast for conditions.

The situation that I described when my rims were overheating, I had a
choice to brake enough to slow in the curves, go off the mountain or
stop and walk. I was able to manage without walking or blowing a tube
but the smell of the rubber burning scared the hell out of me. g

Again, according to one technical article from long ago, for a lot of
grades, maximum rim temperature occurs when you try to hold the speed to
about 30 mph. Descending slower inputs energy into the system at a
slower rate. Descending faster allows aerodynamic drag to take some of
the load.

Unfortunately, 30 mph is about the speed a lot of riders choose for fast
downhills.

What I've always done on hills that were either super steep or had
corners that limited safe speeds was to brake as hard as I could to
near walking speed and then release the brakes until the speed seemed
excessive and then brake again. The theory was to get the bike slowed
down and then allow the rims to cool during the non-braking phase.

I have no idea whether this is effective other then to say that I
never had a tire explode :-)

On Thursday, April 20, 2017 at 8:45:31 AM UTC-7, wrote:
Duane wrote: "If you are blowing tubes because of overheating rims you are going too fast. Or you are braking too much."

Yes, I probably brake a lot and descend slower than a lot of other riders.. Part of that is because I'm an old guy, but you know what? I haven't fallen off the bike in a long time!

Jay wrote "For Retrogrouch: be happy you're not coming up the other side of that climb. It works out to an average 12%."

Yes, I have done that climb a number of times. When I was younger I could do it without stopping, but now I really hate it because I have to get off the dam*ed bike and rest at least once. I don't like to have to do that! People tell me I should get a lower gear, but I dunno. My low is 35 inches, and I think that the day that I am too weak to push that gear will probably be the day I quit riding.

I think that you got those quotes a little mis-ascribed. That was me. And I do not think that going too slow is a problem. Going too fast and then trying to slow up often is. If you ride more slowly there is a lot less energy going into the brakes and hence the rim.

As for climbing - it's just the F-ing weather. Once the sun comes out and we can ride often enough the fitness will come back. I had to stop three times going up Palomares last time. I NEVER stop on Palomares. Even coming up the steep side I am dying over the last 100 feet but I don't have to stop.

And I feel like crap all the time now because I can't ride for one reason or another - mostly weather related but I'm getting cataract surgery now as well. Despite the doctor's advice as soon as there was a clear day I did a nice easy 25 miles.

On Thursday, April 20, 2017 at 8:22:04 PM UTC-7, John B Slocomb wrote:
On Thu, 20 Apr 2017 16:04:41 -0400, Frank Krygowski
wrote:

On 4/20/2017 12:06 PM, Duane wrote:
On 20/04/2017 11:45 AM, wrote:
Duane wrote: "If you are blowing tubes because of overheating rims you
are going too fast. Or you are braking too much."

Yes, I probably brake a lot and descend slower than a lot of other
riders. Part of that is because I'm an old guy, but you know what? I
haven't fallen off the bike in a long time!

Jay wrote "For Retrogrouch: be happy you're not coming up the other
side of that climb. It works out to an average 12%."

Yes, I have done that climb a number of times. When I was younger I
could do it without stopping, but now I really hate it because I have
to get off the dam*ed bike and rest at least once. I don't like to
have to do that! People tell me I should get a lower gear, but I
dunno. My low is 35 inches, and I think that the day that I am too
weak to push that gear will probably be the day I quit riding.


Thanks for the quote but I didn't say:
"If you are blowing tubes because of overheating rims you are going too
fast. Or you are braking too much."

I can't really parse that. The people that I've seen blowing tubes
because of overheating it was generally caused by them wanting to not go
too fast for conditions.

The situation that I described when my rims were overheating, I had a
choice to brake enough to slow in the curves, go off the mountain or
stop and walk. I was able to manage without walking or blowing a tube
but the smell of the rubber burning scared the hell out of me. g

Again, according to one technical article from long ago, for a lot of
grades, maximum rim temperature occurs when you try to hold the speed to
about 30 mph. Descending slower inputs energy into the system at a
slower rate. Descending faster allows aerodynamic drag to take some of
the load.

Unfortunately, 30 mph is about the speed a lot of riders choose for fast
downhills.

What I've always done on hills that were either super steep or had
corners that limited safe speeds was to brake as hard as I could to
near walking speed and then release the brakes until the speed seemed
excessive and then brake again. The theory was to get the bike slowed
down and then allow the rims to cool during the non-braking phase.

I have no idea whether this is effective other then to say that I
never had a tire explode :-)

I've always done this as well on steep hills with dangerous turns in them.

On Thursday, April 20, 2017 at 8:53:47 PM UTC-7, Joy Beeson wrote:
On Thu, 20 Apr 2017 08:45:27 -0700 (PDT),
wrote:

My low is 35 inches, an=
d I think that the day that I am too weak to push that gear will probably b=
e the day I quit riding.

When I had very low gears put on my first real bike, I said to the
mechanic, "I'll be back to get higher gears after when I've built up
some muscle." He answered "No, you will climb steeper hills."

And I'm still riding those gears. But if I make a habit of riding on
150 W, which has a very steep dip with a divided highway in the
valley, I may ask the Trailhouse whether they can install a bigger
inside cog -- I know that I'm already using the smallest-possible
inner chainwheel.

On the other hand, just after I cross US 30, there's a convenient
driveway where I cam pull off and change into walking shoes, and it's
only two miles from there to city streets where I'd want walking shoes
anyway. And all downhill, once I've walked to the top.

Meanwhile, I'm walking down every staircase I can, and if nobody is
looking, I'll walk up backward.

I've learned a new trick for climbing hills when seventy-six: when I
see a hill I'm not sure I can climb, I sit down at the top of the
previous hill and rest for five minutes by the clock. Then I pedal as
fast as I can coming down, and find the climb fairly easy.

--
joy beeson at comcast dot net
http://wlweather.net/PAGESEW/
The above message is a Usenet post.
I don't recall having given anyone permission to use it on a Web site.

When you look at a climb it is almost always far more daunting in prospect than in reality.