norskagent

That is what I am forced to conclude...I tried replacing my 32mm city tires on my 1980 Mclean tourer with some 32mm knobby cross tires for riding more on the gravel roads of our local state park (umstead).
The front tire switchover went smoothly, but apparently I didn't get the rear tube seated properly because when I tried to air the tire up to full pressure (90-100 psi), the tube exploded from being pinched I suppose.
The hole in the tube is right at the valve stem, but now my rim (rigida,france) has an outward warp about 3" down from the valve hole. I have popped tubes doing this before on other bikes without damaging the rims, what happened this time? I rode the bike last sunday and did not feel any bumbs while braking, so I guess the tire changeover did it...Also, any levering I did to remove/replace the tires was with a plastic lever opposite the valve hole.

USAZorro

Are you sure there's nothing else that happened? The last time I blew a tube and noticed a wheel suddenly out of true, I later found the flange of the hub had also cracked.

Check the tension on your spokes and see if something else may have also happened.

StephenH

I would bet that the rim got bent and that's what let the tube blow when the tire slipped off there.

Mike Mills

+1

I'd bet the rim was bent first and that caused the blow out. You just didn't recognize it.

norskagent

That ^ seems to be the most likely scenerio, but I had just put the tube and tire on the rim, wouldn't I have noticed a significant bump in the rim's edge while doing so?

rhm

Maybe, but not necessarily; it's easy to miss things like that.

But to answer your question, yes, a rim can get deformed by a tire blowing off it. I've seen it happen. Sometimes, as the tire is working its way off the rim and the tube is pushing its way out, you can hear spokes creaking loudly, and then, after your ears stop ringing, you find the wheel is out of true. I wouldn't assume a blowout can deform a perfectly trued and tensioned wheel; there may already have been problems with spoke tension. I don't imagine the rim would be bent badly enough that it can't be trued up again, though.

norskagent

here it is. More than out of true. Perhaps the lack of rim tape contributed?

rhm

Woah!

Okay, that is not what I was talking about, I have never seen anything like that, and I would not have thought a blowout could have done that; and I agree, it would have been hard to miss it. You would have felt it in the brakes, if the wheel turned at all. And you're sure you didn't do it with a lever, prying the tire on/off, huh? Freaky!

norskagent

I did pry the tire off, with plastic levers, but on the opposite side of the rim from the valve hole.
Any suggestions for new rims?

miamijim

I'd like to see a close up side shot of the rim. Money in the bank says the rim was cracked and gave way when the new tire/tube was brought up to pressure.

Reynolds 

That looks at least 200 psi-worth!

Panthers007

To your question regards rim-tape: YES! That could well have contributed to causing the blowout. The final act (BANG!) likely had a few factors leading up to catastrophic failure. But riding a wheel without rim-tape is asking for a blown tube. And all that follows. Velox is my favorite.

norskagent

It had rim tape, but there was a ~2" gap in it at the valve hole (see pic). I will look for a rim crack. Perhaps it was dented all along and I missed it because I wasn't looking for it, I don't know.

cudak888 

Looks as if it was bent from a previous impact, and gradually deformed under pressure.

-Kurt

norskagent

Here is a recent pic of the bike taken a few months ago. The valve stem is at ~4:00. Looking at the full sized pic, I zoomed in to the stem area, and could not detect any warp (though it could be there). Seems like I would remember hitting anything hard enough to whack the rim through those fat tires, but I don't.

norskagent

well, since the old rim is toast, I am going to try a quick fix. My lbs had an old mavic 36h rim that matches the profile of my rim pretty well - I'm going to attempt a delicate rim-to-rim spoke transfer operation. Any pointers?

USAZorro

Five.

1. Take a digital picture of the spoke lacing on the old rim.
2. Make certain you lace the spokes the same way on the old hub. Going the other way is more likely to crack the flange. Don't ask me how I know this.
3. Make certain when you start with the rim in the proper orientation, so drive side spokes go in the drive side holes of the rim - and vice-versa. Don't ask me how I know this either.
4. Start with the spokes with heads that seat on the outside. Do both sides of the hub with spokes with this orientation, and save the spokes with heads seated on the inside for #19-36.
5. Make certain you pay attention to how the spokes are crossing (first crosses are over - last cross is under).

Then you'll be on to tensioning. That's another lesson.

mswantak

I'd add two more pointers:

- Don't lace your rim on the living room floor while you're watching TV

- Be reasonably sober

And yes, I learned this the hard way.

badmother

Loosen spokes on old wheel.

Put old wheel on top of new rim on yoyr lap, axel between your legs. Valve holes at exactely same place.

Start at the walve. Mowe and loosely secure spokes one by one .

True new wheel.

norskagent

Thanks! I will let ya'll know how it goes...

lotek 

I'm not a fan of the one at a time method of moving spokes, it sort of messes up the
lacing and cross patterns for me. I use Jobst Brandts method for lacing wheels, it makes it
easy and has good illustrations. I also used Sheldon Brown's guide
https://sheldonbrown.com/wheelbuild.html#lacing
to build wheels. Sheldon does an excellent job, has a glossary and explains things in a much
easier way than Jobst.

marty

Sangetsu

Use tape. Before disassembling your wheels, tape the spokes together where they overlap, and then use string or tape and tie at the overlap points in a complete circle. This will maintain the position of the spokes and eliminate any guess work.

norskagent

Changeover went smoothly. I taped the spoke crossings but it turned out that wasn't necessary, once I lined up the two rims and taped them together. Just went around the rims in order, tranfer complete. One thing that makes it easier when loosening the "old" wheel spokes, if it's a rear wheel, is to loosen all the non-drive side spokes first, then the drive side. Don't ask me how I know this. Now for tension, true, hop & dish...

norskagent

Okay, new problem...When I examined the spoke area that was hidden behind the now removed freewheel, practically every outboard spoke (9) has scratch/gash damage about 1" above the hub flange. Wtf? Now it looks like I should replace those 9 spokes before I finish the wheel...

miamijim

At some point in the past you dropped the chain between the freewheel and wheel. 'Dork discs' serve a purpose.