On Bicycles, and.... what else is there?

Since the retirement of the RS road bike with more "relaxed" geometry, Cervelo has unified its stack-reach schedule, creating a single geometry shared between the R and S series. This geometry is fairly close to the Trek H2 geometry, the more relaxed of the two geometries Trek supports. The logic used by Cervelo is that the vast majority of riders can be fit with a stem ranging from +6 degrees to -17 degrees using this more relaxed geometry. And it's true, but many riders object to a bike like the S5 being touted as an "aero" frame had the longest head tubes. This was especially problematic when using the bike with full time trial bars. Indeed the S5 is sufficiently aero that with time trial bars, it's a competitive time trial/triathlon frame. So a lower stack provides more adjustability and allows more reach for the same stack and a shorter stem for most male riders (small women often benefit from a small reach). Riders claim to prefer the feel of s...

Previously I reported on the Tour Magazine test of "frames under 800 grams" published in the December 2013 edition of the magazine, and summarized on-line. In the article, they weighed the frame, fork, and bearings from a series of light & expensive bikes. They also bent them, measuring the stiffness characteristics. They then calculate a rating based on these and some other minor factors (warranty, quality of finish). But it's interesting to compare these weights to what is claimed by the manufacturer. Those aren't listed in the article. The focus of Tour isn't to investigate the dishonesty of bike companies. Rather it's to determine the truth. Claimed weight is a tricky business. Only Cervelo is totally clear in the matter, publishing a lot minimum, average, and maximum for each size of the RCa frame in their White Paper on the bike. Obviously bigger frames tend to weigh more. If I'm buying a 56-cm frame, I don't care about the mas...

At EuroBike, Cervelo made two huge product announcements, a new S5 aero-road bike, and a revised on the super-premium "would be fun to ride but I can't comprehend paying $10k for a frame and fork" "Project California" RCa. The S5 is an interesting case. Cervelo has a range of aero road bikes: the S2, S3, and S5. The S2 and S3 are the same frame but with different part specs. These were designed for the more average rider/racer, with an aero front end combined with the rear triangle which is basically the same as the R-series road frames. The S5, on the other hand, was designed with the racer philosophy that, as Specialized tweets, #aeroiseverything . The idea is that racers, looking for all marginal advantages, would ride the S5, and give up a bit of rear-triangle comfort. Surprise, surprise. On the Garmin pro team, the S3 got much more use. Racing is a complex dynamic, much different than riding solo in the wind. The riders felt better on the S3 wit...

Tour Magazine did a web feature from an article in the Dec 2013 printed magazine " Lieichte Rahmen unter 800 Gramm ." This featured 8 bikes, all exceptionally priced, which presumably get under the challenging 800 gram mark for a bike frame. Now 800 grams is hardly new. For example, Ruegamer showed a custom frame under 700 grams at the National Handbuilt Bike Show 6 years ago, and that frame is still ridden a ton by weight weenie legend Don Becker of Berkeley. Spin, a company in Germany, was also around the same mass at that time. But production bikes tend to be overbuilt due to the need for mass production margins and since sometimes the fattest riders buy the lightest bikes, irrationally. It's not a good thing if a 100 kg rider snaps his 51 cm frame after hitting a pothole on his 3 mile bike commute. Additionally, 1500 watt sprinters may perceive an extra few mm of flex in a super-light frame, causing irrational fear that precious watts are being squandered. So ...

On a recent ride, I found a shop local to the day job, Cupertino Cycles, had a Cervelo Demo R5. Cool! Since reading the RCa White Paper, I've always wanted to try one. Indeed, I've never ridden any of the Cervelo R-series. Recall, perhaps, the Peloton magazine review of the RCa , the prototype which led to the present R5: There is a fury to the way the bike reacts to power -- it leaps from under you, but the feeling continues beyond the initial acceleration. Each pedal stroke delivers a new surge forward. Who wouldn't want to ride this? Deal is the Cervelo geometry is, as I've described, a bit tall. So it isn't obvious what frame to try. But is low-stack over-rates? So what I did is I started with the geometry for the Fuji SL/1, which is my race bike (since I've done little racing recently, the poor thing is getting neglected). I started with the geometry of the size small, which I ride. I use a +6 degree 11 cm stem at present (I used to use a ...

The old R5Ca, Cervelo's first version of a super-high-end stock bike ($10k for the frameset alone, and people, to my amazement, actually paid it...), used a relatively novel geometry whereby the downtube was offset forward of the bottom bracket. With the nominal 72 degree seat tube angle, this in effect gave a seat tube angle which was steeper for shorter bikes, more laid back for taller bikes. In this case by "shorter" and "taller" I mean bottom bracket to saddle. With most manufacturers the same thing is accomplished by changing the actual seat tube angle from steeper in the smallest size (for example, 74.5 degrees) to more laid back (for example, 72.5 degrees) in the largest. But of course the effective STA doesn't then change with the amount of seat post showing. Here's a plot I did: But this was an experiment they didn't pursue. Maybe it caused too much confusion to dealers. I don't know... In the present version of the R5, and the RC...

So far I've been sticking mostly with main-stream bike brands with the exception of Swift. This time I'm focusing on premium frames, including the stock geometries from custom framebuilders. For reference, I include the Trek Emonda, which is obviously both light and expensive in the SLR with vapor coat model. Then I include the Cervelo RCa, the same geometry as the Cervelo R5, which is the most expensive frame here, at over $10k with the crankset, but it's also (except for geometry) perhaps the best all-around bike ever designed (the white paper is fantastic). Then I include two exotics: the AX-Lightness Vial Evo, extremely rare so far, and the Lightweight frame, which needs to be included by virtue of its name but which actually isn't that light when compared to the Cervelo and Trek. Then there's the Guru Photon, which made a bit splash when it was announced at Interbike around 5 years ago, but for which the low weight shown there was a very small frame built...

I'd left the Trek Emonda out of my previous comparisons for two reasons. One is it's technically a 2015 bike. Note, however, I'd included the Specialized Tarmac 2015, but that was an iteration on an existing bike. But more importantly I left it out because I don't like it. You'd think I would, as it's marketed as a weight weenie special. But, unlike another weight weenie special, the Cervelo R-Ca, the Emonda is designed with down tubes which show an utter contempt for wind resistance. And for what weight savings? 30 grams. Yes -- 30 freakin' frams: the claimed weight for the Madone Vapor Coat H1 is 720, the claimed weight for the vapor coat Emonda H1 is 690 grams. There's a lot of ways to save 30 grams. 30 grams will save around 0.35 seconds up Old La Honda.... which I'm pretty sure will be squandered to wind resistance by the Emonda's bulbous down tubes. If the CdA of a rider on a Madone is 0.35, and if the Emonda is 100 grams equiva...

I previously showed the Canyon Aeroroad. But Canyon's perhaps more popular bike is the Ultimate, a perennial competitor for Tour Magazine's lab-dominated bike of the year ratings. A prime competitor is Storck, a more niche German company known for its engineering-based approach to bike design. Included in that approach is a relatively unique approach to geometry. Here's a comparison of Trek, Specialized, Canyon, and Storck road bikes, where I've left off the endurance bikes this time: Canyon is clearly sticking to the stack-reach design philosophy with both of its models. And for once a bike company does the obvious which is to make the aero bike lower. And the longest Ultimate is incredibly long. It must be those tall Norwegian customers. But the Storck 0.6 is a bit bizarre. The smallest size differs only in stem length, essentially (actually with the head tube angle being slacker than 73 deg, slammed stem will result in the smallest being slightly higher). Th...

Last time I compared Trek to Cervelo for stack-reach. The Madone H1 and the even more aggressive Domane Race were much longer/lower than the Cervelo H1, and even lower than the more race-geometry Cervelo R-series from 2008. The Madone H2 and Cervelo R5 were comparable. The Trek Domane 6 was substantially more relaxed than the Madone H2. It's really designed more as a century bike than a race bike, although it may provide a good fit for some racers. Here I compare the Specialized line to the Trek line. I already looked at the 2015 Tarmac. In the following plot, I add in the Roubaix endurance bike as well as the Venge aero road bike: The Venge is basically identical to the Tarmac. The Roubaix is fairly close to the Trek Madone H2, not nearly as relaxed as the Roubaix: around 2.5 cm spacer difference. The Madone H1 is more aggressive than the Tarmac, however: with two lines of Madone they can afford to be more aggressive on the longer/lower version. This suggests for racing...

Previously I plotted the Trek Madone stack-reach. Consistent with using "race bikes" from other manufacturers, I used the more aggressive of the two geometries, the H1. The H1 used to be called the "pro" geometry, in contrast to the more relaxed "performance" geometry, but Trek decided, apparently, that this implied the more relaxed geometry was a lower standard, compelling weekend warriors to buy bikes which didn't fit them well. So the "pro" became H1, and the "Performance" became H2. In addition to the Madone, the Domane is also a legitimate race bike, sold for comfort at some cost in mass. The standard Domane, as is the standard with "endurance" bikes, has relatively relaxed stack. To compel professional riders, most notably Fabian Cancellara, to ride the frame a lower-stack model needed to be developed. Since the UCI requires bikes given to professional riders be made available to the public, Trek made availabl...

More stack-reach comparisons, retaining the tall (Cervelo R5) and long (Trek Madone H1) winners from last time: First, there's a new obvious "tall" winner, and that's the Parlee Z5 tall model. Of course this isn't a fair comparison, as it would make more sense to compare the Parlee tall geometry to the endurance geometries of other bikes, but I put this here for comparison since I recently test-rode a Parlee ESX. The regular Parlee Z5 geometry corresponds to around 2.5 cm less spacer height, and has more traditional road racing geometry (clearly not designed to a stack-reach spec, however, since the curve zig-zags). Specialized is interesting, as the smallest 3 models are essentially constant reach, changing only in stack. This is because top tube length is directly canceled by seat tube angle. This keeps the reach the same as the top tube is lengthened. The bikes still fit bigger riders, however: adding spacers to the smaller frames would bring them to a...

More bikes added to the stack-reach plot I showed last time. It's tempting to add more and more but I run out of colors, and humans have only 3 color receptors so there's contrast only between so many... Again the mostly vertical blue lines indicate points which can be matched to fit with the same stem but with more spacers on the lower stack, longer reach frame. Spacers reduce reach and increase stack. I additionally added mostly horizontal blue lines, which are spaced by 1 cm spacer height apart, again assuming a 73 degree head tube. These lines would correspond to points which you could reach with the same spacer height, but different length of 0 degree stem. Of course stems aren't typically 0 degrees 6 degrees, 10 degrees, and 17 degrees are popular, and these can be flipped positive or negative. But the spacing between these lines is the key point. For small riders, Cervelo and Swift rule, Swift providing less stack, the Cervelo geometry at this size only rela...

Last time I noted that Adam Blythe when he switched from the BMC Pro Tour team to the NFTO continental team his stem went to something truly disturbing: a giant horizontal protrusion from the front of his otherwise very nice looking Swift Carbon frame. The obvious explanation is frame grometry: the BMC allowed a lower, longer position than the Swift. So I decided to check this. Here's a plot of reach (x-axis) versus stack (y-axis) as reported by various frame brands (I need to be careful not to say "manufacturers"). I compare the BMC SL01 with the Swift Ultravox Ti, along with two favorite references, Cervelo old (2008) and new (2014). Slight digression: Cervelo decided to take a fresh look at geometry back in those days by setting a seat tube angle of 73 degrees for all frames. They reasoned that the human body when it's shorter or taller is still optimized by the same seat tube angle: the desire for steeper seat tubes in smaller geometries is more driven by ...

Adam Blythe, 2013 BMC, 2014 Continental team NFTO, won the London-Surrey Classic this past Sunday in a remarkable upset, beating the World Tour riders otherwise dominating his winning breakaway. I watched the final 10 km on youtube, although that video seems to have since been pulled. Too bad -- it was an impressive final. Adam was there with 5 pro tour riders including Sky's Ben Swift and BMC's former world champion, Philippe Gilbert. Although Blythe was on BMC last year, obviously his preparation for this race was handicapped by the lack of top caliber race opportunities available to his team, NTFO. Despite this, he took his share of the pulls, longer pulls than some of the others. Surprisingly there were no attacks in the final kilometers, the group instead working together until the end game began well within the final kilometer. Adam went from relatively long, not wanting to get jumped by Swift, and it worked. He held his gap to the finish, winning his home ...

For a long time I've been alarmed by the trend in carbon bikes to go to fatter and fatter tubes in a never-ending quest for higher stiffness-to-weight ratio. Indeed the trend predates carbon fiber: it goes back far further, to Cannondale, and before that, Klein with their fat-tube aluminum bikes. To save a relatively small amount of mass, giving up a large amount of wind resistance. But then as the quest for lighter carbon frames started approaching a limit, there was an effort to gain performance elsewhere. So wind resistance got renewed interest. Starting perhaps with the Kestrel Talon, there were a series of "aero road" frames which, at the cost of around 200 grams more or less, performed much better in the wind tunnel. These frames had a hard time catching on with professional riders, however. Road cycling is performed mostly in packs, with fatigue and avoiding crashing both major factors, so optimizing the bike is a lot more than optimizing speed at a given po...

I was watching a tutorial for some modeling software when I saw a reference to Lagrange multipliers. Lagrange multipliers... it range a bell from my distant past but I didn't recall what it was. Fortunately Google is my friend and I pulled up a video from MIT on a "recitation" -- what MIT calls sessions with teaching assistants which occur between lectures taught by professors designed to provide practice, review, and supplemental material. The problem posted on the video was the following: suppose I want to optimize (maximize or minimize) a function f(x, y, z) = x 2 + x + 2 y 2 + 3 z 2 , where the solution is constrained on the unit sphere: g(x, y, z) = x 2 + y 2 + z 2 - 1 = 0 Lagrange multipliers are based on the assumption that for points g(x, y, z) = 0 if the function f(x, y, z) is optimal along contours in g(x, y, z), then the gradient of f(x, y, z) and the gradient of g(x, y, z) must differ only by a scale factor λ, assuming the derivatives of both functi...

In 2009, Caltrain projected 72 thousand boardings by 2030 , a rate of annual increase of 2.3%. These projections are obviously extremely important, since capacity increases need to be planned well in advance. Indeed, as was predicted by essentially all rational observers at the time, the ridership has exploded far in excess of that "extremely conservative" schedule, Ridership survey reports are available here . Here's the annual ridership: At the rate ridership has been increasing it would hit 72 thousand not in 2030, but rather in 2019: A key thing, though, is that ridership will not increase at this rate. There simply is not the capacity. At some point trains get so full that the experience of riding on the train is worse for a sufficient number of passengers than the experience of driving, or the experience of working from home, or the experience of moving closer to work, or the experience of changing jobs closer to home, or the experience of moving to Portl...

I was looking at an excellent web page in how to make your own wall-mounted bike rack ( link here ). But one aspect of it was bugging me... the calculation of the force acting on the hook in the wall. I encourage you to look at that site -- it's a bit annoying in that it requires you to click through 5-separate ad-laden pages to see it all, but I suppose that pays the bills. Here's my diagram of how the rack would look on my wall... either in the recommended arrangement of hanging the bikes wheel up, or in a way a bike shop friend of mine recommended, wheel down. Either or a mix would be compatible with the 2-tier arrangement of hooks. With only a single tier, you'd need to alternate up-down. Here's a separate example of such a rack with bikes hanging from the front wheel: Going back to the original web page where the bikes are also hung from the front wheel, the part I'm most interested in here is on page 3, which described the physics. Here's the ...