Metal Valve Stems

[beedawg]

The reason I'm interested in these is that my rubber valve stem broke at either the end of the straight on in the first turn at Road America last weekend.

Was this the factory stem?  Was it dried out?

This was not the original stem, but it wasn't new, either.  It was the same style as the original, and I bought it at my local Ace Hardware store.  The brand name is Victor.  I'm not sure how old it was, but it passed my visual inspection, i.e. no visible cracking or other signs or wear or abuse.  After the tire went flat, I could see cracking around the stem in several places.

[pkpk]

Well it's clearly proof that you ride too fast.     

[aschendel]

but he was on a track, there were no unforeseen risks.

a.s. 

[pkpk]

I know, it was a glib comment.  I forgot the smiley.

[aschendel]

mine was a glib comment too, i was piggy-backing on your poking fun at brent to poke fun at the track is safer/controlled people. 

a.s.

[pkpk]

Duh!  (That is poking fun at myself.)

[Deplorable, thank you!]

I just wanna point out that the .7 ounce metal-and-rubber 90* stem that Lloyd posted is probably the kind that I heard criticized.  The base is rubber, and it's a press-fit valve stem.  It's likely to flex at speed, so it's going to get worked and possibly fatigued.

The picture in my original post is of a valve stem with a metal base.  A nut inside the wheel presses a rubber seal against to inside of the rim to hold the valve in place and seal the air in.  Not likely to flex at speed.

I don't have the exact one you show, the straight metal one I ref to, just has an oring on the top and bottom to seal the metal stem to the rim....the one you pictured has more of a grommet....(so perhaps it is .5 ounces?)

 yes the 90* I show, well I only put those on cruiser bikes, where they are less likely to see trip digits (much)..it was simply for picture and weight comparison....

At any rate---my point was/is............the weight difference is going to be very insignificant on a 22-25 lb wheel assembly and likely not the cause of any vibration

[carlson_mn]

I have an all metal 90 degree unit on my front that works just great.  I've often spun it a bit to get pressure easier and no problems in 10k miles. 

[beedawg]

I have an all metal 90 degree unit on my front that works just great.  I've often spun it a bit to get pressure easier and no problems in 10k miles.

The front tire on a sport bike is usually the harder one to get an air chuck or pressure gauge on because of the rotors, so that's the one that could benefit most from a 90-degree valve stem.  But I don't understand your comment about having spun it a bit to get pressure easier.  Maybe it's just too late in the day and I'll get it in the morning.

[beedawg]

mine was a glib comment too, i was piggy-backing on your poking fun at brent to poke fun at the track is safer/controlled people. 

a.s.

But the track is safer, and I proved it.  If you had a flat at 145 on the street, your bike (or hair) would start on fire instantaneously, and you'd be lucky to survive it.  I didn't even pee in my pants.  Much.

Really, though, the track would be unquestionably safer than the street if we rode at street speeds on the track.

[aschendel]

mine was a glib comment too, i was piggy-backing on your poking fun at brent to poke fun at the track is safer/controlled people. 

a.s.

But the track is safer, and I proved it.  If you had a flat at 145 on the street, your bike (or hair) would start on fire instantaneously, and you'd be lucky to survive it.  I didn't even pee in my pants.  Much.

Really, though, the track would be unquestionably safer than the street if we rode at street speeds on the track.

I don't disagree with anything there, but it's not "safe" (which nobody has claimed, safer, yes, safe, no) and it's not as controlled as many believe / would have everyone believe; your cracked valve stem "proves" that, in my humble opinion.  mid-corner intermediate / advanced and people'd have been affected, potentially very seriously.  i don't mean to thread jack and was just sliding a little veiled opinion into your thread at first.

say, what is the primary benefit of switching to the style you picked?  i assume it's easier to use and less prone to failure?

andy

[carlson_mn]

I have an all metal 90 degree unit on my front that works just great.  I've often spun it a bit to get pressure easier and no problems in 10k miles.

The front tire on a sport bike is usually the harder one to get an air chuck or pressure gauge on because of the rotors, so that's the one that could benefit most from a 90-degree valve stem.  But I don't understand your comment about having spun it a bit to get pressure easier.  Maybe it's just too late in the day and I'll get it in the morning.

If I have it turned perpendicular to the rotors for easy access it hits the calipers as the wheel spins.  So I tuck it into the middle while riding and turn it over to side when checking.  I wasn't sure if that'd be hard on it, but it's been just fine. 

[beedawg]

If I have it turned perpendicular to the rotors for easy access it hits the calipers as the wheel spins.

I hadn't thought of that.  Maybe the 25-degree one wouldn't hit the calipers.

[beedawg]

I don't disagree with anything there, but it's not "safe" (which nobody has claimed, safer, yes, safe, no) and it's not as controlled as many believe / would have everyone believe;

On the track, we just eliminate a bunch of things -- like oncoming traffic, intersections, wildlife (although I once had to brake hard for a deer in Turn 3 at BIR, and I once saw a turtle on the track at Grattan), pedestrians, really lousy drivers, cars and trucks, debris, guard rails, telephone poles, and long wait times for emergency personnel -- so that if we do crash, the risk of serious injury is less than it would be at the same speeds elsewhere.

your cracked valve stem "proves" that, in my humble opinion.  mid-corner intermediate / advanced and people'd have been affected, potentially very seriously.

I think you're saying that if someone had been riding close enough to me, I might have taken them down.  Is that right?  I had just passed some people at the end of the straight, and I don't know how close they were to me.  No one went down, though.  I would argue that my valve stem leak was probably the result of poor maintenance rather than high speeds, and that getting a flat in rush hour traffic would have been potentially much more dangerous. 

say, what is the primary benefit of switching to the style you picked?  i assume it's easier to use and less prone to failure?

I'm after the "less prone to failure," but the "easier to use" is a nice feature, too.

[aschendel]

a.s.