Data freaks: careful with that GPS cyclometer!

An ugly secret exposed about GPS measurement: it’s not always accurate. Although this article is about GPS watches for runners, it certainly applies to cyclists. The article can be found here: http://www.nytimes.com/2011/12/20/health/nutrition/gps-watches-may-not-track-runs-accurately.html?src=recg

For years Roger and I have been using handheld Garmin GPS devices for cycling, and recently I’ve been using an uber-expensive Garmin 800. We’ve always had these devices in addition to a regular cyclometer and we have noted the discrepancy in mileage between them. We have been careful to accurately measure the rollout distance at a specific tire pressure on a weighted bike in order to calibrate our cyclometers. One possible confounding error is the reliability of the wireless signal from the transmitter to the computer head. But in general we’re fairly confident in the accuracy of the cyclometers. Looking in detail at the path created by a series of GPS track points one can see that a track around any curve is simply a set of line segments. So, to us it has been rather amazing how close the GPS-measured distance usually is to that of the cyclometer. Typically our experience over a 50 mile route might be a discrepancy of one- to five-tenths of a mile. That’s pretty damn good. On the other hand, we’ve had some whoppers too. We did a ride in Austria this past summer and the difference was about three miles out of about 60, or roughly 5%! There didn’t seem to be any obvious reason why we would have such a difference. One day on our tour we were cycling near Hallstadt, which sits on the edge of a lake underneath a huge granite cliff. Our GPS signal rather abruptly severely degraded (as did that of other cyclists) and we had a track which had us cycling in weird zigzags over water! Surprisingly, the measured distance for the day wasn’t too far off between the Garmin and the Shimano cyclometer.
My recommendation is that you have a choice, use a GPS device which measures distance using a wheel sensor rather than relying on the GPS signal alone. For example, the Garmin 800 and 500 allow either. But the new Garmin 200 measures distance only by the GPS signal. Of course, unless you’re a data fanatic it really doesn’t matter, does it? And, if you have serious aspirations for ‘improving’ your cycling (i.e. going faster), then distance isn’t an important training datum anyway. Of course, for bragging rights it’s EFI!

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Sports Basement Holiday Fun-Raiser

This Wednesday, between 4-8pm at the Sports Basement Potrero Hill (only) get 20% off on all merchandise for Different Spokes members, freinds, families and more.

Show your membership card at the door, grab a beer and shop away!

This is a non-hosted event, show up when you like to take advantage of 20% off on anything.

See the flyer for more details!

Ralston Bike Bridge

Jamie Guerrero took in the opening of the new Belmont Bicycle Pedestrian Bridge on Saturday, check out the photo:

He notes: “The peninsula’s most voluptuous bike bridge. Note the helmet-height and handlebar-height smooth scrape plates, and angled fence for anti-claustrophobia. The roadway is lit, not your eyes.”

Adventures in the near Arctic—Climbing Mt. Hamilton

It wasn’t of Shackletonian dimensions but it was still pretty damn cold. This year’s annual fall Mt. Hamilton ascent on November 5 was a narrow escape from a snowstorm.

Last year the long run of good luck with the weather ended when it got rained out. This year we were hoping for a better shot and we were granted our wish but just barely. The forecast had a storm front hitting the Bay Area around two p.m. If it were slow moving, then we’d probably make it without getting drenched, as the storm wouldn’t arrive in the South Bay until later. But if the forecast was off just a little, then we were in for a ride of epic proportions, as in slip-sliding through the snow off the top of the hill. Just to add to the fret-fest, the morning weather report showed that there had already been snow on top of Mt. Hamilton, and the UC Lick Observatory weather station had the temperature pegged around 33º F. But the day would warm up and it would all be gone when (or if) we reached the summit.

Mt. Hamilton riders return to the parking lot
Narrowly missing a drenching!

The turnout was pretty big, over a dozen, for a climb in excess of 5,000 feet, and it wasn’t just the usual suspects. David Gaus and Karin Atkins were co-leading the ride; Sharon Lum, who originated this ride for the club oh so many years ago, was again AWOL, which was truly unfortunate as she had the nasty habit of bringing delicious muffins to the start of this ride, and they were sorely missed. (Please come back, Sharon!) The day’s greyhounds turned out to be Tim, Peter, and that erstwhile tortoise Chris Thomas, who now conquers climbs like Casanova conquered women. Somewhere in the middle were Roger and I (on the tandem), Frank, Bob, and Judy. Taking it easy that day were the two Davids, Nancy, Gordon, and Karin.

Unfortunately the Fates conspired to make things difficult even before the start. David Gaus was unable to retrieve his bike from his storage due to a maintenance toad who had rekeyed his locker and didn’t bother to get him a replacement. David eventually caught up with us after a frantic morning chasing down a key. I guess our delayed start (but does a Different Spokes ride ever start on time?) and our patient starting pace were just enough for him to catch on. Fortunately, despite David’s absence Roger, Chris, and I had been up Mt. Hamilton before and we were able to provide a rough description of what the ascent would be like and what the group would confront. There was much moaning and kvetching about the anticipated altitude gain.

Then the group, already chomping at the bit, took off at a frenzied pace. Peter and Tim, who have a penchant for getting lost at the drop of a cycling cap, bolted out of the parking lot and promptly missed the first turn but sheepishly managed eventually got back on course. Although Roger and I ostensibly were trying to provide guidance, half the group was already out of sight. Tim and Peter pulled into the portapotties in Alum Rock Park which, lucky for them allowed us to catch up. They promptly passed us just as they were about to miss yet another critical turn if we hadn’t shouted out to them. Who was ahead and who was behind was all rather murky to us. Those that were ahead we just had to presume could follow the map and cue sheet. We waited at the turn for the others and led them up the short climb the presages the Big One.

As expected, as soon as we started up Mt. Hamilton Road, we started to spread out on the road, each of us taking a pace that would allow arrival at the summit without imploding. Roger and I, being on the tandem, had figured we would be pulling up the rear. We are not especially ferocious on the climbs due to the extra mass of the tandem. But we have lots of character! I had been looking forward to chatting during the climb with Karin, who admits to being a *slow* rider. But she and a bunch of the others just disappeared behind us due to what we learned later was a minor ‘mechanical’. So again we were on our own. Suddenly Chris appeared and roared past us, a man on a mission. I thought he was way ahead of us. “Extra miles!” he said. “Intentional?” I asked. “Nope!” he responded and off he went.

Despite the chilly start we were now thoroughly warmed up, sweating even. Off came the jackets. A high overcast concealed the sun, any warming from it muted, although it wasn’t yet needed. Mt. Hamilton Road is a long slog, about 18 miles covering 4,000 feet of net vertical to the observatory. The climb is not monotonic—there are actually two short descents of two or three hundred vertical feet, which give brief respites. But on a day like today even those short descents meant a chilly blast against sweat-soaked jerseys. On the positive side, the recommencement of the uphill segments, usually a point of bemoaning, was greeted with joy by our now benumbed and shivering limbs.

Halfway up, at Grant County Park we ran into Bob. From him we learned we were, surprisingly, in the middle of the group. Gordon, Nancy, Karin, and the two Davids were still somewhere below. As we waited, we saw a family of wild pigs silently walking through the meadow hunting for food. We waited, thinking the rest of the group surely must be just behind us and would soon catch on. But we were rapidly getting chilled and uncomfortable, so off we went despite the discourtesy. As we ascended the temperature continued to drop and the chill became more pronounced. Any stop at all, to drink or pee, and the warmth of climbing vanished in an instant and gave way to shivering. Despite being a Saturday the road traffic was minimal—the occasional automobile and just a few motorcyclists go racing by. The quiet, the solitude, the dreary weather along with the gelid temperature made it all very atmospherically wintry.

The grade of the climb above Grant County Park averages about six percent versus five percent for the lower climb. At this point you can make out the Observatory in the distance. The road winds around dozens of curves, allowing the Observatory to peek in and out of view, seeming close yet still miles away and literally thousands of vertical feet to go. It’s tantalizing and agonizing at the same time. Time seems to stand still, and if not for the odometer you imagine the effort is completely futile. Then suddenly you’re on a set of switchbacks just below the Observatory and the road then levels out. By this point we have caught and passed Frank who has clearly felt the effort of the day. Chris passed us heading down; apparently he’d been to the top and did not want to linger and get frozen. As we made the final turn up to the Observatory we passed Bob and then we were there. When we got to the top, did we take in the view or high-five each other for our accomplishment? Nah, we headed to the vending machines in the back hallway where we could inhale some Cokes and paste our bodies against the wall heater!

To our relief, there had not been any snow and the road had been dry. It felt arctic, and according to Tim the temperature is in the low 30s. One certainly doesn’t want to prance around outside, especially in sweaty clothes.

Other cyclists trickled in and everybody was relieved to get out of the cold and warm up at the heater. Both Bob and Frank crawled in. Poor Bob was in just shorts and a long-sleeved jersey—no windbreaker, tights, or shoe covers.

Where was the rest of our group? Tim and Peter had arrived long ago and were hovering in the main alcove of the observatory. But Judy, who had passed us at the very beginning, was not to be found. About 20 minutes later she showed up, apparently also having done some extra miles! The weather appeared to be stable, but it was now two p.m. Where was the storm? Waiting for the others meant risking getting caught in either rain or snow. With no cell service at the top (note: we have AT&T) no one could get an update on the storm. Nearly 45 minutes after we had arrived the rest of the group minus Karin showed up. Everyone was happy to have the climb out of the way and survived the frigid conditions. The wall heater suddenly got crowded!

The problem with going inside and warming up was that going out to the cold seemed bitterly painful. As a long time bike commuter I’m used to riding in all weather conditions. But the wintry weather has come on so quickly after a welcome Indian summer that I’m simply just not yet used to the cold. I had on an undershirt, long-sleeved jersey, windbreaker, and then a fully waterproof jacket, a wool cap with a cycling cap over it, and toe covers, and I was still shivering! For insurance I had brought along some chemical handwarmers. I broke those out and gave some to Roger to shove into his gloves so that he could steer us safely down the mountain.
When it comes to weather I’ve found that prayer is rarely effective. So, even though Karin still was nowhere to be found, we decided to head out in order to try to beat the storm. David Goldsmith headed out with us and soon zoomed ahead. One would think a tandem would blast down any descent ahead of any single. But Mt. Hamilton road is very curvy, narrow, and has marginal sight lines, all of which make a single bike a much better descent vehicle. David was soon completely out of sight. The tandem felt sketchy and unsteady; Roger was shivering so hard that I could feel it in how the bike was handling! I was silently praying that we make it down in one piece unhurt. I offered Roger the rest of the heater packs to pack under his jersey so he could warm up some more, but he declined.

The descent was a whirlwind of curves, tight turns and chicanes. Whether it was the cold or just being tired, the whole experience felt vertiginous, banking through turns one after the other. We quite literally did not have to pedal at all until we got to the first short uphill. But both of us were shivering and so tight from the cold and lack of effort that this teensy climb felt like we were going up Alpe D’Huez (and that ain’t no exaggeration because in 2006 we had crawled up the Alpe on the tandem!) The climb was so short that we weren’t warmed up by the time we had to descend again. This had to be one of the least enjoyable descents I had ever been on. (Well, except for the ones where I crashed. And the one where I got hypothermia because it was snowing and all I had was a tee shirt and Bermuda shorts. Oh yeah, and the one where the fog was so thick that I couldn’t see.)

By Grant County Park the temperature was noticeably warmer (but not warm), and the second short ascent brought a welcome glow to our frozen legs. We were starting to feel human again. There was still no storm in sight even though the sky was ominously darker. In a trice we were down the final descent and back to the edge of San Jose. That’s when it started to rain. At first it was just a few random drops, then it became a regular pitter-patter. Being just two miles from the car we knew we were in pretty good shape, and our legs were pretty cooked from about 5,500 feet of climbing. So we just rolled on at our weakened pace even though we knew the storm was hitting.

David was already back in the lot putting his bike on the rack when we arrived. Just as we got off the bike the rain’s pace picked up and we rather hurriedly got the tandem and ourselves into the van. Then the sky opened up. But where were the others? We thought they were just minutes behind us. Surely they were getting drenched! Soon it was a raining, not hard, but enough for everything to get a good soaking, perhaps also including our fellow Spokers. It was about a half-hour before the others finally showed up, and in a turn of good luck they were so far back that the front wasn’t as ferocious up on the mountain. They got wet but not overly, so all was good. Everybody was grateful for the good luck in getting down without having to deal with a blizzard.

What better way to close out such a frigid day than some hot Indian food. So off Roger, David Gaus, and I went to Naan ‘N Masala in nearby Milpitas for some flame-throwing curry!
See more pics over at the Different Spokes Photo Gallery.
—Tony Moy

FYI – Sunday Nov. 6 Golden Gate Bridge West Sidewalk Closure

This Sunday November 6 if you are not planning on attending the club’s Morgan Territory/Mt. Diablo ride in the East Bay and instead plan on staying closer to home for your riding, be warned that the west sidewalk of the Golden Gate Bridge, the side we usually cycle on, will be CLOSED from 7 to 9:30 a.m. for the 5,000 expected runners in the US Half Marathon. Cyclists may instead contend with the pedestrians on the east sidewalk or use the FREE shuttle which runs from the parking lots at either end of the bridge.

And don’t forget that daylight savings time ends at 2 a.m. this Sunday also. So, that 7-9:30 a.m. closure period is an hour later than you think!

Foxy’s Fall Century

DSSF members and ALC friends converged on Davis for the Foxy’s Fall metric and century rides this year. It was dark when we parked, and I had to remind myself that it was mid-October. So while we got a later start for the century than I would have liked, all turned out find for a relatively flat (near) century (this years route was modified, and instead of being 102 miles, was down to 95.)

The first 24 miles were relatively flat, quick and and the groups got split up, a stop light or two facilitated some of the split. Eventually Gordon and I caught up with Bob McD, who was again riding on “fire” similar to day two of the Double Bay Double. If I remember correctly, RS# 1 is where the metric route splits, and we left Bob there, and he waited for the rest of the metric group to arrive there. I tried to convince him to join us on the century route, but he held true to sticking with the metric group. I later got a text from him wondering if there were any hills, on the century compared to the metric.

Lunch was at Wooden Valley School at mile 50, with a water stop in between. David’s B and S caught up with us there, and just as we were leaving, so did Nancy. It was warmer out here, and the main climb of the day, Highway 121 on the way to Moscowite Corner was next. An interesting feature on this ride, they have on-the-bike SAG on the route, in addition to the vehicles with bike racks. There was a couple on a tandem, in fact.

Rest stop 3 was at Lake Solano Park, and Gordon and Scott pointed out that this was one of the overnights on Sierra to the Sea, and the reverse climb is called Cardiac Hill. Oh joy, since I am planning to do that next year. The last 22 miles brought us along tree lined roads before the outskirts and neighborhoods on the way to the Veterans Memorial ride start. And to my pleasure, I finished my first century in 6 hours (exactly.) I enjoyed Foxy’s, it being a nice day, a great group and no headwinds! 🙂

http://app.strava.com/runs/1988846/embed/42498b01d28e85459ed4d8e3ed2d158d14200bd4

Old La Honda-Tunitas Redux

While we did not have the wonderful Indian Summer day I had hoped for to redo Chris Thomas’ Double Bay Double training ride to San Gregorio and back, we did get the weather that Karin had hoped for, a bit cloudy and coolish, but not bad at all. We were joined by a fellow ALC TRL and rider, Judy, and the three of us set off from Mountain View to meet up with Nancy Levin, at the start of Old La Honda. We missed Nancy at the bottom of OLH.

Climbing Tunitas Creek was a first for Karin, and she did great, despite my inaccurate description of the climb. In my mind, the 9 mile climb is broken into thirds with the bottom and top each being not that difficult. I’ll remember next time, it’s more like the bottom and top quarter, with the middle 4+ miles being tough. But in all fairness, I did say that the climb is doable with no steep grades. Nancy headed back to her car from Skyline, while Judy, Karin and I did our lunch stop at Roberts Market and then we continued on Chris’ planned route, which included the extra “evilness” of Elena Road. Thanks again Karin, for co-leading with me. It was a fun day, even more so because I was in the minority, nice to see a 3:1 ratio for a change. 🙂

http://app.strava.com/runs/1824661/embed/977dd98d19eeeb6215d102ebe969e1ea0cf22fbe