Brewster

Friday evening, the start of Memorial Day weekend, was my third annual ride from home to Brewster on Cape Cod, via a fast ferry from Boston to Provincetown. The bike setup was based on the century 0f the previous weekend - for example, the fenders were still on. I added the big headlight and the relatively new Garmin HCx GPS.

As you may recall, I broke our previous GPS on a long ride last year, apparently from vibration through the handlebar mount. That was disappointing given that I used a handlebar mount made by Garmin, exactly as intended. This time I was determined to be more conservative, even though the new unit appears stronger than the old. I decided upon a couple layers of vibration dampening before the handlebar mount. First, I moved it to the end of my (carbon) handlebar so the length of this tube can deflect a bit to absorb bumps. My hands and upper body help dissipate shock and vibration here, especially when I'm "in the drops" as I am most of the time. This vibration dampening is the main reason I use a carbon handlebar. After that, I attached the GPS outside the foam handlebar tape, so the tape itself is a cushion. On the tape I mounted a short extender piece, which then had more handlebar tape on its tip, then the Garmin handlebar mount. And I tried not to compress any of the handlebar tape more than necessary, so the foam would retain its softness.

I left home after work and made good time down to Cambridge. I started the GPS as I approached the end of the bike trail, but it was unable to acquire satellites as I rode. At the end of the trail I stopped the bike and restarted the GPS, while I reworked the GPS mount. (It proved too loose on one layer of handlebar tape, so the whole unit kept flipping upside down.) The GPS locked normally this time, and I continued across Cambridge and Boston toward the ferry dock. One segment of the trip is still a puzzle: the bumper-to-bumper stopped traffic in front of the museum of Science - this time I tried the leftmost lane for a while, and that worked pretty well, but the sidewalk is likely the fastest route if I were willing to ride it.

My hopes for the new GPS included improvements in the routing algorithm. Both old and new units have a mode for "bicycle", but the old one didn't seem to act much different from "car" mode. Around a mile from the ferry dock the new GPS gave me a different turn from last time, evidence of algorithm progress! I landed at a security kiosk I'd never seen before, in front of a beautiful arch reading "World Trade Center". The route is already more scenic! Immediately after passing the arch, though, I found why I'd never seen this before: I was two floors above ground level! Rather than explore, I walked down polished stone stairs with my bike, stepping gingerly in my awkward bike shoes with their metal cleats. I'll take the old route next time.

After a quiet ferry ride, I started the second part of the ride as the sunlight waned. In Provincetown, the GPS periodically tried to divert me to Route 6, instead of the quieter 6A I've used before. The good bit of preparation I did included putting last year's route on the screen of this new GPS, so I could compare it with the GPS advice. (The bad part of my prep was neglecting all forms of paper maps and instructions.) After I merged with 6, the GPS started finding little zig-zag roads to divert me from 6. This must be a new "bicycle" algorithm - it was nuts. Route 6 is not very bad (PMC uses a lot of it), and it's obviously faster and smoother than the side roads. It's also pretty obvious that zigzags are not a safety enhancement since most of them require crossing the highway. After I figured out what was happening I just used the 2008 route and stayed on 6.

It was dark when I reached the transition to the Cape Cod Rail Trail, roughly my halfway point on the Cape. This was a lovely ride like last year, though very different in character because the weather was great this time. Here I turned off the GPS routing entirely, leaving it as a map only, and I turned off my other beeper too. No more gadgets or cars, just trees and wildlife - this was delightfully peaceful. A line of radio towers looked like an alien invasion as I neared then passed through the plane of their aircraft warning lights. I chased a coyote, rabbit and raccoon along the trail. The rabbit was the only foolish one - it veered away from my path then reconsidered and jumped high in the air in front of me. A quick stop prevented impact, but I can't figure out what it was thinking. Why not wait till I'm past to cross the trail? Maybe it recognized me as a mountain biker and offered me a bunny hop salutation?

This segment ended quickly too, and the ride was done. I've been buying water between P'town and the trail head, but from now on if I'm on this year's pace I'll skip that.

I concluded the GPS is vulnerable to vibration, preventing its lock on the bike trail. While it worked fine after lock, this makes me nervous that something is moving inside the unit, perhaps the antenna. This sounds like a recipe for metal fatigue, so I'm going to try to figure a way to give it yet more isolation from vibration. Ugh. Also, next time I'll try the "car" routing algorithm instead of "bicycle", and then constrain it to minimize highway use, etc.

CRW Spring Century 2009

Yesterday the calendar reached the CRW Spring Century, the first big ride of the year. Landing at the end of a busy week, the preparations were not altogether stellar.
Base Miles: check! Commuting a couple days per week through most of winter gave me confidence I could finish the ride.
Long rides: not check. I managed zero rides longer than a commute this year, and my longest route of 25 mi happened only once or twice.
Bike condition: check! I found time the day before to put the fenders back on for the forecast rain, and to put on a new chain. I've ridden the bike on enough commutes to be confident of the other parts. (It's taken a bunch of maintenance this year though.)
Sleep: not check. A party the night before turned into an extended tarot reading featuring rounds of JC's delicious and hearty margaritas. Then I had trouble sleeping as I alternated between feeling hot from the tequila and feeling cold from the fresh breeze through the window.

Luckily, by the start of the ride the forecast had calmed to just morning rain, and as we riders gathered for the start the rain was light. I briefly considered taking off my vest and leaving my glasses in the car but instead I left well enough alone. Four friends of mine had tentatively planned to ride this, so I kept a lookout while the start assembled, but I couldn't find anyone. The ride started late, and in waves, and after standing around in the rain around 20 min I was happy to leave with the first wave - the self-selected fast riders. In the back of my head I heard the advice of my late father in law, "don't ride with the young bucks", but it seemed preferable to more waiting.

The pace picked up as we warmed up, but I held on reasonably well in the group-ride style of previous CRW centuries and the PMC. About half an hour in, a cold front with strong rain came through, and I was very happy I'd never taken off the vest. In fact, a full jacket would have been nice though I wouldn't have stopped to put it on. My glasses also saved me - I was quickly reminded that group rides in the wet mean riding into the continuous fantail from the wheel ahead.

After an hour, my plan to avoid pulling at the head of the group finally unravelled. Pulling means doing more work than anyone else in the group, breaking up the still air. Over the first hour we'd averaged 21MPH, which for me is unsustainable and even unwise. Trying to pull this group was doomed to fail, but it was my turn. I pulled briefly, up to a stop sign, overcooking myself so thoroughly that the group passed me after the stop and I could not keep up. I was "shot out the back of the peloton (group)," as the race announcers say.

I rode alone for a while after that, then was caught by a rider I recognized from the lead group, named Tim. He wanted to work with me as a pace line (taking turns pulling for each other) to try to catch up to the leaders. We tried, but had such different styles that we weren't effective, and my legs were so weak that I told him I couldn't help him anyway. He didn't give up; then we found we'd missed a turn. I was ready to turn around but Tim pulled out a big street map and plotted a course to intercept and possibly save a mile, which might help us catch up. Tim's plan worked beautifully, and when we finally crossed another CRW mark, I was thrilled and shouted to him, "Thanks very much!" Tim was still focused on catching the leaders, and the vital question became how the distance of our route vs CRW route compared. I had to pull over to figure this out. I wanted to keep riding but I figured I owed him for getting me back on track, so we pulled over and I searched the cue sheet as Tim got out his map. Then the leader group zoomed past us and we jumped back on the bikes and tried to catch up. Tim made it, I did not. I never saw any of them again, but after a couple miles I was content with the situation because I couldn't have held their pace anyway.

After a while I reached the commercial center of Exeter, NH. The problem is I wasn't supposed to do this - I'd missed another turn, and turned around to backtrack.

After the first water stop (near the halfway point of the ride) I saw the mark for the first left of the route to the last stop, but then no confirmation marks, and after another mile I turned around again. By this point I felt quite discouraged at my inability to stay on the route, but fought to stay committed to it. (And I redoubled my efforts at checking marks and noting the mileage when I reach one.)

At the two-thirds mark, I caught up to a couple individuals on the ride. This was encouraging as proof I wasn't the last one on the route, and that my pace was somewhat reasonable. I said Hi to the folks and rode behind one briefly, but I shortly decided I wanted to pass them. I tried to let them tack on behind me, and they seemed to take me up on it informally. But just as we were starting to get organized, the markers indicated we were to turn onto a closed road, into a gap between a pair of Jersey barriers. I shouted the news back and rode through the gap. It was about three feet wide, not unlike some bike path barriers on the Cape Cod trail, so I didn't sweat it much but the other riders fell back enough to lose drafting. After a short ride on this road, with grass growing through the pavement, the exit pair of Jersey Barriers came up. Again I shouted back the news, but then as I bore down into it I realized the gap was narrower, about 2 feet, and I started to regret my decision to take it at speed. I wish I'd at least pulled my hands from the handlebar drops up onto the top to save some width, but I just held it and rode cleanly through. Whew! This pair of obstacles was not on the route before!

The last water stop was near mile 75, meaning mile 80 for me including my wrong turns. At this point my Achilles were getting sore and I would have been pretty happy to be done for the day. As I snacked and refilled my bottles, I heard two people give up, seeking rides back to the start. And I heard another had given up at the first stop near mile 50. I've never before heard of someone dropping out of these rides. While I felt sad for the folks pulling out, the news encouraged me too. It wasn't schadenfreude, rather an external confirmation that this was a tough ride and I wasn't the only one feeling beaten down.

From here I faced just 25 miles to the end, just like my summer commute home from work. I counted down a few different ways: miles covered, miles to go, water bottles remaining, ETA. And I sang to myself what I could remember of Joan Osbourne's Spiderweb, with a little bike dancing thrown in. My emergency double-caffeine Gu helped me celebrate 15mi to go. In short, I pulled out all the stops to finish the ride.

In sum, I'm glad I did the ride in terms of my training. I learned a bit about following route markers. But riding alone for most of the day was less fun than the centuries with DP and TT.

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Technical note: One of the many bike tech debates is whether to trust the lubrication that comes on a new chain. Without much planning, this ride was an experiment and it confirmed Jobst Brandt's argument that it's a good lube and so well applied that it's probably the best lube job the chain will ever have. I rode a new SRAM PC-951 on this ride with just the factory lube, and it ran smooth and quiet throughout the ride. I heard a bunch of squeaky chains just after the second water stop. And my fenders make life much harder for the chain than if I didn't have them - I'll guess three times worse. (Very few other riders had fenders.)

Two Flanges per Hub, Please

Tearing apart the FSA three-flange hub design.

[This is a rant about bicycle physics, perhaps the first in an occasional series. It's written for someone conversant with bike mechanics. Unfamiliar words are likely defined in the Glossary by the late Sheldon Brown. I'm heavily influenced by Jobst Brandt, and in this case I recall he heaped derision on this three-flange hub, but did not explain much about why. He has written an excellent book about the mechanics of the bicycle wheel.]

Strong wheels are wonderful. But modern wheels have traded off as much strength as possible in a quest for lots of gears in the cassette. If excess strength remained, the cassette would get deeper, but instead since the ancient 7-speed cassettes, cassettes have stayed about the same size and the chain side plates have paid the price, getting driven to thinner and more expensive designs.

A conventional rear wheel is a careful balance of forces to form a reasonably strong yet lightweight structure. The difficult kind of strength to provide is lateral: resisting sideways forces on the rim. Spokes act only in tension, so the rim's lateral position is held by tension in the spoke set on each side of the rim, the drive-side set and the non-drive set. The drive set has a small bracing angle, meaning the spokes are almost in a plane parallel to the rim, but they do pull toward the cassette. The total lateral force from the drive set is perfectly balanced by the lateral force of the non-drive set, but the non-drive has a larger bracing angle so the non-drive tension is lower. (This describes a hub with equal counts of spokes on each side, like my Shimano ones - other designs exist but are ultimately comparable.)

A properly built wheel has the following balance: the rim is compressed to the limit of its strength (or is close to it) by the sum of the tension in all the spokes. The spoke tensions are matched within a given set of spokes, but different sets may have different tensions.

In a conventional wheel, the limiting factor in lateral strength is getting enough lateral tension on the drive side with the limited bracing angle. The drive side spoke set also handles the majority of the torque transfer from the cassette by increasing tension in "pulling" spokes while reducing tension in the lagging spokes. These spokes are doing a lot of work!

The FSA design has three flanges: a pair in fairly traditional locations, laced radially, plus a third flange in the rim plane with a large diameter and crossed spokes to transfer torque. Radial spokes cannot transfer torque. Each spoke set has a third of the total spoke count (8 each, rear), and the even spacing of the rim holes tells us the spoke tensions are all similar. The rim design is conventional, so total spoke tension is about the same as a conventional wheel. But since the drive-side spoke set 'lost' a third of its spokes to the center spoke set, the drive side lateral bracing force has been cut by about a third. There's no way around this - the wheel is substantially weaker than a conventional wheel.

Jobst's quick take on this was that this design is so bad the whole company should be avoided by his readers. That's bad news for me, since their chainrings have received good reviews, and they're a player in the crank market which has for the moment abandoned road triples like mine. If FSA were to offer a good triple, I'd like to be able to consider it - but I'm afraid I'd have trouble ignoring Jobst's advice.

If you're interested in more about bicycle wheels, get it from the horse's mouth.