Bike Noob

Because I'm Always Learning Something New

How Much CO2?

by // 9 Comments

One of the A riders in the club posted on the Yahoo group that he was making the move to CO2 cartridges, after many years of resisting them. That started online discussions that took two separate tracks.

12g threaded

Another member asked, “How many pounds of pressure does a 12 gram cartridge impart to a 700×23 tire? I use 16g cans and still have trouble getting home with the optimum 92-94 lbs onboard.”

The Internet is a wonderful thing. It doesn’t take long before answers start rolling in. Multiple answers.

“I’ve never checked the actual pressure,” answered a fast rider, “but my 23’s are quite firm after using a 12 gm cartridge. I just did a bit of research and it appears that you get about 100 psi in a 23mm tire from a 12 gm cartridge and about 125 from a 16 gm.”

But that doesn’t allow for individual differences. The fellow who posted that probably doesn’t weight more than 130 pounds soaking wet. The original poster followed up:

“Am I the only one who rides 25 mm tires? What did your research say about the pressures in the larger road tire?”

Cripes. We haven’t answered the cartridge size question yet, and now we’re introducing tire size variations? It’s gonna get confusing.

“I ride 25s too,” chimed in another member, “and am somewhat heaver than Steve so you probably will not be surprised to hear that I only roll with the 16s on the road bike.  However, I also put some Gatorskins on the wheels so I don’t get flats very often any longer [although I just jinxed it and am sure to get a flat on my next ride] so the extra cheese spent on the threaded 16 gram cartridges isn’t a big deal.  If you use less than 6 of these a year, it’s not a major expense.” But he also had a practical suggestion.

“Go buy a 12 gram and a 16 gram cartridge.  Let all of the air out of your rear tire, fill it up with the 12 gram cartridge, and go for a ride.  Repeat with the 16 gram.  Which did you like better?”

I imagined pffffft! sounds coming from garages all over the neighborhood as cyclists took him up on that idea.

16g unthreaded

Then, of course, there’s that complication you get with CO2:

“Bear in mind that CO2 bleeds out of a tire much faster than pumped air,” wrote the 130-pounder, “so if you fix the flat in the early part of a three-hour ride, you will find a lower pressure when you get home. This is why, after fixing a flat on the road with CO2, I always deflate the tire and refill it with a pump at home. However, unless it gets down in the low 80 lbs range, you shouldn’t have any problems short of a pinch flat if you hit a big pothole or rock.”

Okay, this is all good information. But one member had a great idea: Go right to the source. The Genuine Innovations website has a link to an inflation chart.

“Unfortunately there isn’t a measure for the 25mm tire,” said the guy who suggested experimenting. “But there is one for 23 and 28. You should be right in the middle. It looks like a 12gm will get you 90psi in the 23mm tire and 62psi in the 28mm tire or about 80psi in the 25mm. If you want a higher pressure, go with the 16.”

What was the second discussion track? Cost, of course.

The original poster wrote: “If you buy cartridges from a bike shop they can be pretty expensive. I just checked online and it appears that you can get them reasonably cheap if you get a bunch of them. For example you can get a box of 50 16 gram non-threaded cartidges for $50 including shipping. And different prices for different amounts. but 50 for $50 seems about the best.”

Another replied, “Buy a box of 12 gram cartridges at Walmart in the BB/paintball gun section. 15 for $7.97.”

“+1 on that recommendation,” said a third.  “I buy mine in bulk from a discount sporting goods store.  The only thing is that these do not have the threads to screw into some of the smaller nozzles.  I had to use it this weekend and a single Crossmark CO2 cartridge inflated my tire in one shot.”

Well, that was settled pretty quickly. Looks like a bunch of my club pals are headed for Wal-Mart to get their CO2. But one of the previous commenters signed off with some wise advice:

“Even though I’ve had good luck with cartridges, I still have a frame pump attached to my bike just in case Mr. Murphy is drafting.”

 

 

 

The Mysterious Popping Bar Tape

by // 7 Comments

Here’s a weird one: When I went into the garage early Sunday morning, with an idea to get the bike ready for the club ride that I never went on, I discovered this:

For some reason unknown to me, the bar end plug had popped off overnight, unraveling the bar tape. When I put the bike away after the last ride, Friday, it was okay. When I was in the garage to get into the car Saturday, it was okay.

What happened?

I haven’t any idea. I had taped the bars some time ago, probably in early fall, and hadn’t had any trouble with them since. I had even taken a scrub brush to them the last time I washed the bike, and got off most of the dirt smudges. The bar end plugs had held the tape in place much better than some of my previous tape jobs.

My next reaction was that I had to fix it, and fast, if I planned to ride that day. I’d already decided the foul weather would keep me from doing a club ride. Logically, I would have waited a few hours until the bike shops around here opened for their short Sunday hours, then picked up a new roll of tape.

But sometimes, I don’t think logically.

I removed the tape. It looked to be in reasonably good shape, so I decided to use it again.

Now, the usual advice you get when you go online for a refresher on winding bar tape is not to reuse it — get new stuff. I can understand that. But the tape wasn’t torn or otherwise damaged. I started winding it on the bar, paying close attention to the amount of tension I kept on the tape. You want it to be taut. You don’t want it to be so taut, it tears. I managed to stay on the good side of that fine line and got the tape rewound on the bar. Heck, it would look new, except that the rewind had uncovered some grungy dark areas that will have to be scrubbed clean again.

By the way, this is not high end bar tape. This is the run of the mill stuff I picked up at Performance. It’s a cork gel, and costs only about $10 for enough to do both handlebars. I like it. I like spongy tape that provides some cushioning, and this does that. Some riders say they prefer a harder tape that transmits road feel back up to the hands. I’m perfectly happy with the feel I get from this tape.

I’ve ridden the bike a couple of times since retaping the bar. It’s holding well.

Have you ever reused old bar tape? What were your results? Did it last as long as you’d hoped, or did it break down in a short period of time?

The New Old Crank Set

by // 3 Comments

As we neared the end of the year, some issues with my bike started cropping up. Because I am me, I immediately diagnosed them as problems with the front derailleur. Because I am me, my diagnosis was 100 percent wrong.

The problem was a noise — a sort of a creak — that started whenever I pedaled in the small chain ring. When I shifted to the big ring, it was quiet. On a club ride two weekends ago, I spent as much time as possible in the big ring, just to keep from hearing the noise. But some hills were involved in that ride, and riders near me were treated to a “creak — creak — creak” noise whenever I applied power or started climbing.

I dropped it off with our club’s bike mechanic, who was surprised to be seeing me again so soon. He’d just done some work on my rear derailleur. The next day, he sent me his verdict: bad crank arm and bottom bracket. My mind  brought up memories of  an incident that happened on a New Year’s Day ride. My left crank arm fell off. Having to tighten it before each ride after that got old fast, so I got some blue Loc-Tite and smeared it into place. Once it cured, no more crank arm problems.

Don's crank set.

I was pleased about that, because I liked this setup. Guest blogger Don Blount had sent me the crank set after I’d posted about needing 172.5 mm cranks instead of the 175s that came with the bike. The shorter crank arms let me deliver more power to the pedals. But it turns out my fix was only temporary, and in the long run it did damage. The bike mech summed it up:

“The noise issue appears to have been started by a degrading crank.  The non-drive crank arm appears to have worked loose over time.  This damaged both the crank arm by wallowing out the splines and, because it allowed for play on the crank, ended up damaging the non-drive bearing on the bottom bracket.”

The only way to fix the problem, he said, was to replace both the crank and bottom bracket. Yech. But I had a solution, sitting right in the garage — the original crank set and bottom bracket that came with the bike.

The original.

He put them on, and I was rolling again the next day.

Because Christmas intervened, and we were out of town for five days, I haven’t ridden it much yet. I have gone out on some short rides with my wife, and really pushed hard today when we did Veloway laps. I will have to lower the seat a bit — maybe not the full 2.5 mm the new cranks have added to my pedal stroke, but enough to keep that twinge away from my knee — and futz with the saddle, because lowering it means I have to put it back a bit, too. Heck, I haven’t had the bike fitted for almost two years. Maybe it’s time to do it right and make an appointment to get it done right.

—–

Click to embiggen.

Christmas was a modest affair around our house. Pat set a low gift expense limit, so neither of us went overboard, but we both got what we wanted. I got some new wool socks, because I like the ones I have so much. But these are truly high-tech socks. They’re even sized for each foot. And they tell you which one, right on the toe. Makes me feel like being in kindergarten again, when we had red ribbons tied to our right shoe so we would be able to learn left from right.

Recent Posts

Categories

Archives