Bike repair: replacing chainrings

I have no idea why the gears in the front of a bike are called chainrings. The set of gears on the back of a bike are often referred to as sprockets, and a collection of integrated sprockets as a cassette. They are all gears to me, but if you call them by special names the mechanics at the bike shop will take you more seriously.

The chain was slipping a lot on my 2000 Bianchi Volpe, particularly when I was trying to accelerate hard. This frequently happened when I was trying to cross an intersection. It wasn't safe. The front and rear derailleurs looked fine, so I suspected it needed a new chain and new chainrings.

I stopped by my LBS (Local Bike Shop) and bought a new chain. I explained the slipping I was experiencing, and the mechanic told me a new chain would probably make it worse. Still, a chain is cheaper and easier than chainrings, so I thought I'd try it.

The bike mechanic was right. Or, at least, the new chain didn't help. It was time to replace the chainrings. And this is where things got complicated: what do you replace them with?

When you try to buy chainrings, there are a lot of different factors that come into play. One was the number of teeth. That was pretty easy, I could just count them. My larger chainring had 52 teeth (52T), and my middle chainring had 42 teeth (42T). I decided to leave my smallest chainring, which had 30 teeth (30T). It rarely gets used and didn't look very worn.

My bike's drivetrain is a Shimano Tiagra, but I didn't know the exact model, which complicated things. I could easily see that the crank had 5 arms, so I needed chainrings with 5 bolt holes. Then there is another measure, called the BCD (Bolt Circle Diameter). This has nothing to do with the size of individual bolts, it's the diameter of the circle that would pass through all the bolt holes. The 2 best sites for explaining this, and how to measure it, were:

My chainrings had a BCD of 130mm.

Another wrinkle is that some drivetrains use 2 chainrings (doubles) and some use 3 chainrings (triples). I'm not certain this is totally critical, but it is important that the outer chainring is meant to be an outer chainring, and the middle chainring? Probably OK as long as it's not mean to be an outer chainring. Yet another wrinkle is that chains can vary based on the size of the cassette. By bike has a 9-speed cassette, so I looked for chainrings that were designed for something similar. It looks like there's some wiggle-room there, but I don't know how much.

It's possible I worried about this way too much. My friend Chuck has cobbled together bikes out of all sorts of incompatible parts. But this was my first attempt to replace chainrings, and I wanted to get it right, if possible.

Eventually I deduced, based on some of the measurements I'd determined, that my drivetrain is the Shimano 4403. That's an old drivetrain and Shimano doesn't make any new 4403-specific parts. But some bike forums suggested that the 4403 was pretty standard, didn't do anything particularly strange, and that parts should be relatively interchangeable. I ended up with FSA Pro chainrings, 52T/42T, 130mm BCD, 5-bolt pattern.

I watched a couple YouTube videos, both from English bike mechanics, before attempting the swap myself. Better to see it done a couple times than to wing it, right? Well, mostly right -- in both videos they removed the crankset from the frame. I was unable to get the crankset off my bike, but it turned out I was able to remove the old chainrings and replace them with the new chainrings without removing the crankset. I didn't even have to remove the pedals! I may have had to remove the crankset if I wanted to replace the smallest chainring, I'm not sure. You do, of course, need to remove the chain and put it back on when you're done.

After the repair, I took the bike out for a quick spin. Smooth ride. No chain slippage, even under load. Shifting wasn't great, but no worse than it was before the repair. It was a success!

I am leaving these notes here in case any other amateur bike mechanics are trying a first-time chainring swap. Good luck, it's not as bad as it first appears!

Reading List for English 317: Quest for Utopia

Taught by Prof. Gorman Beauchamp, University of Michigan, Fall 1995

  • The Republic, Plato
  • Utopia, More
  • "Of the Cannibals", Montaigne
  • Gulliver's Travels, Swift
  • Looking Backward, Bellamy
  • News from Nowhere, Morris
  • Notes from Underground, Dostoevsky
  • We, Zamyatin
  • Brave New World, Huxley
  • 1984, Orwell
  • Woman on the Edge of Time, Piercy
  • The Handmaid's Tale, Atwood

My top reading list from college.


S24O - Sub 24-hour Overnighter

Apparently that's a trend now: camping trips that take less than a day.

Anyway, inspired by a co-worker who biked to Duluth this week, I decided I needed to bike somewhere too. It was time to load up my bike with tent and sleeping bag and head back to the Carver Park Reserve and find the bike camping site.

I left on Wednesday night at about 7 P.M. Although I made very good time, sunset was around 8:30 P.M. and soon I found myself riding in the dark, under a canopy of trees, with just a sliver of a moon. I have lights on my bike, but they are really intended to help other people see me, not to help me see the trail.

And I had my sunglasses with me but not my regular glasses, so I got lots of gnats in my eyes. What a weird way for a gnat to die. You're just flying along, and then splat: a giant eye hits you.

In the darkness, I saw a large shadow cross the trail. A dog? A deer? A wolf? An axe-murderer? A mountain lion? Bigfoot?

I finally got to the turn off the main Minnetonka LRT trail to the Carver Park Reserve. It had an eerie feel in the dark, like I was the only person on this slightly strange planet. And then, around a blind curve, 2 other cyclists riding 2-abreast come careening at me. "Sorry!" one of them said.

Signs that in broad daylight would be hard to miss were suddenly inconspicuous, and I had to stop at every fork and see which way I needed to go.

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Bike Ride: Minneapolis to Carver Park Reserve

After a miserable hot and humid Friday and Saturday, it rained Sunday morning and the weather cooled. The sun came out and it was a beautiful afternoon. I was inspired to go for a ride. Looking at a map, I picked Excelsior, on the southern shore of Lake Minnetonka.

I took the Cedar Lake Trail/North Cedar Lake Trail to Hopkins, and missed my turn to pick up the Minnetonka LRT trail, which I realized when I stopped to admire Shady Oak Lake and discovered I was on the wrong trail. Note to self: turn north just past Luther Hopkins Honda.

Ride a block or two through downtown Hopkins, catch sight of a giant raspberry statue, and then catch the Minnetonka trail. It's a crushed limestone trail, but is a smoother ride than many of the asphalt trails. There are frequent stops while you are in town, crossing mostly quiet residential streets. There's a Lunds & Byerlys supermarket right off the trail between Hopkins and Minnetonka if you need to refuel.

Somewhere along the way I saw a sign that said "Carver Park Reserve, 16.1 miles." I've been contemplating an overnight bike camping trip there for some time, so I adjusted my destination accordingly. Excelsior was still en route.

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Bike Ride: Minneapolis to Stillwater

This ride was recommended to me by my doctor, who is also a cyclist. Usually I head west, where you can get out of town in just a mile or two. Instead I headed east, through St. Paul.

The Route:

  • Dinkytown Greenway to Transitway
  • Transitway to Como Avenue
  • Como to Avon (?)
  • Avon to Wheelock Parkway
  • Wheelock Parkway to Gateway Trail
  • Gateway Trail to Brown's Creek Trail
  • Brown's Creek Trail to Stillwater

29 miles each way. There are sections on Como, Avon, and Wheelock where bike lanes disappear, but other than that you are not sharing the road with cars.

Stillwater is on the St. Croix river and features a Main-Street-turned-Mainstreet-of-Yesteryear tourist attraction vibe that I honestly can't stand, but at least you can get food and Gatorade and sit a spell before you hit the road again.

Much of the two state trails are heavily wooded and provide plenty of shade. Look out for turtles on the trail, while are, as you might expect, slow-moving.

In spite of replenishing electrolytes with the previously named sports beverage, I still managed to get muscle cramps in about 3 different leg muscles almost immediately into the return trip. I kept the bike in a very easy gear and just pedaled through the cramps. Remember, potatoes have more potassium than bananas, so...pack some French fries?

The Dream Syndicate at Fine Line Music Cafe, 5 Dec 2017

This was my first visit to the Fine Line. This venue is 3 blocks from my apartment, and it's charming inside. Exposed brick, streetlamps along one wall to make it look like an outdoor cafe. I bought the slightly pricier reserved table seating in the balcony. You walk upstairs, and there is a table that literally has your name on it, a carafe of ice water and plastic cups waiting for you. I would absolutely do it again. Any band at all. It just felt first class.

The guy at the door put my 21+ wristband on. No one was carded. If you've heard of this band, you are definitely over 21. 21 twice over and half again! Part of the light show involved the reflective surface of the many bald heads in the audience. The crowd was a little thin, I suspect the recent snow and resulting road conditions kept a lot of people at home.

I only know this band via Pandora, where a couple of their songs ("That's what you always say" and "When you smile") have been popping up on post-punk stations I've created for years. Apparently their first album was a college rock hit in '82, but that star must have faded.

The opening act was Elephant Stone, laid-back psychedelic rock, fun but less Stone Roses than the name would have you believe. One of the members played a sitar for a song or two, sitting barefoot on a dais. At a table near me, an audience member impressed her friends by identifying the instrument as a sitar, which I thought was a little sad, but I can't tell an oboe from a clarinet so who am I to talk.

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Movie review: Inception

Like your Thanksgiving leftovers, here's a hot take served cold: I just saw Inception for the first time, and it wasn't a very good movie.

First of all, have you seen Dreamscape? From 1984? Just so we have that out of the way.

OK, so now we have layers or levels, dreams-within-dreams. So what? A big part of my problem with the movie is that the various levels are all action-packed garbage. It's action that doesn't even advance the plot: it's there to try to create suspense or a sense of urgency because the death of a character in a parent dream means they die/disappear from the child dream.

The problem is that it's hard to create suspense if you're not invested in the characters. And I definitely was not invested in these characters. You get to the end after an hour or so of feeling like you're flipping aimlessly between channels showing 3 different James Bond flicks. The final shot is where you're supposed to think, wait, is this a dream? or is this real? does he care if it's a dream or if it's real? Instead the feeling I was left with was who cares?

As far as people who get really into discussing what this-or-that means in the movie, I have a feeling they are the same people who found The Matrix exceedingly clever.

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Ministry w/Death Grips, Minneapolis, 27 Oct 2017

I had been indecisive about whether I was going or not--did I feel like showing up?--but the day of the concert I went out to see if tickets were still available.

I made it about 2 blocks before I turned around and went back for a jacket. It was cold! A benefit of living downtown.

The line to get in went down the street and around the corner. I walked past the venue to see if there were separate lines for have-tickets and need-tickets but it looked like one line to me so I added myself to the queue.

I often have remarked that no one smokes anymore. That was not true of the people near me in line. I was surrounded by some of the trashiest people I've rubbed shoulders with in ages. And the eavesdropping -- they were clearly idiots. Although I overheard a conversation where people were proud of some younger relative winning an essay contest, and he would be traveling to D.C. He's so smart, look how much he's grown, etc. One Ministry fan said that Death Grips was too avant-garde for her tastes.

Venue staff were coming around checking IDs and applying wristbands. "Is this the line to buy tickets?" No, he said, up by the doors there's a crowd of people smoking. You should go there.

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Minneapolis Bike Tour

Reading over the Star Tribune, I found an article describing all the traffic woes for this weekend, including numerous road closures for the Minneapolis Bike Tour. I mean, I just did the St. Paul Classic last Sunday, and the weather was looking good, so why not?

Somewhere within Theodore Wirth Park, I heard a hiss-hiss-hiss sound and realized I'd blown a tire. I pulled off to the side and went through my pannier bag to find my spare inner-tube and bike tools. I popped the wheel off and quickly pried the tire off with a tire lever.

Several people called out as they passed by: "Got everything you need?" Yep, I said. I felt very scout-like, I was prepared!

Nevertheless, a man in an orange volunteer t-shirt arrived soon thereafter. Bob, one of the ride marshals, offered assistance. Much appreciated, since roadside repairs are a little different than garage/workshop repairs. He reminded me to check the inside of the tire for damage or debris that would puncture the replacement tube. It seemed OK. A couple more marshals stopped by, which was also helpful because we were having a hard time getting the wheel back on past the derailleur, in part because of my confusion around what high and low gear is on a bike.

Which, by the way, is the opposite of the terminology we use for automobiles. Which is, frankly, moronic. Seriously. Maybe there's some technical explanation, but it is not intuitive.

I was back on the road in just a few minutes. The day started out cold, but my hands were no longer numb and I was starting to feel good. Unlike the St. Paul ride, much of the route we took was familiar to me from my usual weekend outings.

Around mile 29 or 30 though: hiss-hiss-hiss. Not again! I pulled off to the side and checked the tire. This time, it was obvious: a big hole in the tire itself. Another participant called out: "Got everything you need?" The marshals could help me with a tube, but a tire? Maybe they could have, but it seemed less likely. Fortunately I was only a mile from home and, even better, only 2 blocks from Misfit Coffee. The pour-over Papa New Guinea there is my favorite local coffee.

Coffee in hand, I walked my bike home and locked it up, traded my biking shoes for running shoes, and jogged to the finish. Inspired by Ricky Bobby, from Talladega Nights. And after all, there was a free beer from Utepils waiting for me, and I'd told Bob I'd find him later to talk about the Tour of Minnesota ride.

So that's what I get for quadruple-patching a bicycle inner-tube! I stopped by the One on One bike shop later in the afternoon to pick up a new tire and 2 new tubes: a replacement and a replacement spare.

It was a beautiful day, and I regret nothing.

St. Paul Classic

Last weekend I participated in the St. Paul Classic, an organized bike ride around the more easterly of the Twin Cities.

I was initially planning on doing the full 45 miles (short loop + long loop), so the day before I decided I should fix the slow leak in my rear tube. Every morning before my commute I re-inflate it, and every evening on the return it's a little low. When I removed the tube, I discovered I had already patched it twice before. I inflated it a little, submerged it in water, and found 2 more small leaks.

I prepared to patch them and discovered the tiny tube of vulcanizing glue in the patch kit was either empty or dried out. I walked to Target and picked up a tube of Shoe Goo.

The thing is, I have a spare innertube! I always take a spare tube with me on long rides. I could have replaced the tube, now with 4 patches, with a new one.

I told Flaster about this, and he asked if innertubes had gone up in price, or if the university wasn't paying me enough.

I think I have a problem, I said.

It's not a bug, it's a feature, he replied.

It felt a little weird paying $50 to ride a bike, something I've been doing for free most days anyway. They did give out bananas and cookies every 10 miles or so. I ended up riding just the 30-mile loop, since getting to the start of the ride and back home was another 12 miles, and I still had to pack for my trip to Champaign-Urbana later that day.

Group rides and organized rides are weird for me, because I'm usually just by myself. And I wasn't there with anyone I knew, so I was still by myself, but surrounded by a couple thousand other cyclists. I think I ride faster when other people are around, it spurs a feeling of competition that I typically try to avoid. But it's fun to breeze past a group of riders with matching Lycra jerseys.

In case you were wondering, the new patches held up and my tire remained properly inflated. Good as new?