Pinnacle’s Flat #2

Not even one week later, the Pinnacle experiences yet another flat tire!

Thankfully, the flat occurred to the front tire – which is much easier to remove. That is where the “good” news ends…

After pulling the tube out of the tire, the sun had officially set. Determined to patch the tube and get things good to go, I used the horrible bicycle repair stands to inflate the tube to find the punctures.

There wasn’t just one puncture, but two. Two patches get applied, and when everything was reinstalled and I was inflating the tire, another problem happened.

The valve stem separated from the tube, followed by a loud “psst…” and the tire flat once again. And that was the end of the tube.

Prepping for life on the road…

While the 1981 Free Spirit Pinnacle is “going away” soon (rather, just being replaced and retired), I’ve decided that the moment of purchasing tools for simple roadside repairs has been long overdue. (Plus, I can liberate myself from the crappy bicycle repair stands.)

So I went full circle and purchased two new, el-cheapo “Bell”/CST tubes. These tubes retain air fairly good, and they don’t break the bank. Two tubes – one to replace the damaged tube and the other as a spare – set me back about $9.

Then there’s the tools aspect. I was eyeing a repair kit that would have everything¬†but the wrench needed to remove the wheels on the Pinnacle, but I decided that it should be an addition for later down the road. (Most modern bikes have quick-release wheels, such as the Pinnacle’s replacement. But the Pinnacle was a lower-end bike during a time where quick-release wheels were more common on upper-level bikes.)

I also spent the extra money and purchased a compact pump. Unlike my current floor pump, it can fit in my backpack and go with me easily. The downfall is that it takes more time to inflate a tire, a lot more effort, and can present a problem that I’ll mention later. It outperforms the crappy bicycle repair stand pumps by a long shot, as the stand pumps only get to about 20 PSI before tapping out.

So, my “starter” roadside bicycle repair kit is started. I’m hoping to expand it, but so far I’ve decided this is pretty much all I need since the Pinnacle runs fairly fine outside of tire problems.

The kit consists of an adjustable wrench, compact pump, and a spare inner tube.

Today I actually put the tools to use by replacing the old tube that had its valve guillotined. I realized that I should’ve got a pair of tire levers, but thanks to some old gift cards and the help of a friend, I was able to pry the tire off and retrieve the old tube.

I was actually able to get the tire pumped up to between 40 and 45 PSI before having to switch over to the floor pump. That would be enough to get you out of a pickle and home. (On the Pinnacle’s planned replacement, that would actually be in the lower end of the recommended inflation range.)

After getting the tire fixed and getting a bite to eat, I returned home and got this picture of the Pinnacle at night.

Pinnacle at night.

Common Failure Modes of Tires

With the Pinnacle, I’ve experienced a lot of the common failure modes that tires can exhibit. It may be worthwhile to mention these so that you may not make the same mistakes I have.

“Crack! Psst…”

One of the most frustrating but common flat tires I’ve experienced with both the Pinnacle and it’s short-term replacement, the Superia, was the valve stem splitting itself from the tube.

The valve

You’ll walk out to your bike and start pumping up your tires when the valve stem splits, followed by all of the air escaping from the tire. This is how the Pinnacle’s tube failed the other evening after patching it.

Once you remove the tube, you’ll find a hole in the tube where the stem originally was located.

The valve stem hole…

In the world of inner tubes, the valve stem is probably the most abused and stressed component. The rest of the tube acts like a donut-shaped rubber balloon, with the valve stem being where the air goes in (or out.)

Unlike a balloon however, that stem has to extend through the rim into the outside world, where air can be added or removed. The rim can put considerable strain on the stem, especially the tire is underinflated or the tube was incorrectly installed.

This stress can lead to the stem splitting from the tube. The rubber surrounding the valve is reinforced, but after a while it can no longer take the pressure (no pun intended) and splits.

This can be caused by putting excess stress on the valve stem, such as flexing or bending it when pumping. This is my main concern with the compact pump – is that it puts added stress on the stem that can eventually cause it to snap off.

Once a valve stem splits from a tube, it’s game over for the inner tube. A severed valve stem can’t be repaired.

I have, however, seen one instance where this issue is taken one step further.

Earlier, while preparing to wash the Pinnacle in this post, I found the tire had went completely flat. It appeared that the valve stem patch had “melted” away from the tube, causing it to no longer hold air. Occurred to a $10 “thorn-resistant” tube from a reputable manufacturer. The tube was trashed and replaced with a standard-thickness Bell/CST tube.

The valve stem patch came unglued.

Blowouts, bulges, oh my!

The other thing I’ve both experienced first and second hand were blowouts.

One day I decided to overinflate a tire and test its limits. On that particular bike, a similar tire that had a recommended pressure of 45-60 PSI held fine when inflated to 80 PSI. (Yes, you’re eyes are not deceiving you. That tire held on at 80 PSI.) The other tire, however, wasn’t having it. At around 65 PSI, I was rounding a corner when I saw the tire bead split off the rim, and the tube started to bulge outward. After a quick jog away and about twenty seconds, the tube popped with a loud bang that wasn’t dissimilar to that of a gunshot. Truth be told, I didn’t want to go near that bike since I knew the other tire was overinflated by a good 20 PSI.

On that same bike, a small hole appeared in one of the tires which let the tube slightly bulge out. Dumb me, I started fiddling around with one of the “tube bubbles” when I pressed too hard and punctured the tube, which blew air all in my face.

I’ve seen other blowouts, either caused by damage to the tire, improper installation or inflation, and damage to the rim (next paragraph.) A lot of installation problems appear after a bead wasn’t seated properly, or the tube was caught under the tire, lifting it up and off the rim.

Rim Damage

The Pinnacle was made in 1981, predating hooked rims. Modern tires have “hooks” molded in the bead that latches onto a hook molded into the rim, providing a pretty strong seal. Without the hooked rims, modern tires can only be inflated to a certain point before it pushes itself off the rim.

I didn’t know that until I went online. So the Pinnacle blew a couple tubes in this manner with new tires. When inflated to their recommended 90 PSI, the rim couldn’t handle it and the tire blew off. Each time it sounded like a gunshot, and I’d have to walk the bike home with a ringing ear.

With that being said, those rims were fairly popular on vintage low-end bikes. Other damage to rims, such as impact spots and structural damage, can’t just give you a flat: but can cause you to crash.

One more thing: when installing a new tube or tire, always check the rim strip. This is the only thing separating from a tube under pressure from the spoke nipples that can ruin your day by puncturing your tube. (Often, “spoke nipple flats” can’t be repaired.)

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