|Tech Features Road MTB Cyclocross Track News Photos Feedback|
Edited by John Stevenson
Got tech? Send press releases, news, and tech questions to the Cyclingnews tech-heads.
Navigators Tap into Power
Headsets - Why Integrate?
Carbon cage update
The Navigators Team announced earlier this week that it will be using Graber Products' Power-Tap as training aid in 2002. The Power-Tap, a system that uses an instrumented hub to measure a rider's power output, will be used to optimize training and measure performance during selected events.
Navigators' Director Sportif Ed Beamon said, "Measuring power has become an increasingly important instrument in constructing and evaluating a comprehensive training program, especially at the professional level. Studying the relationship between work, heart rate, and power output has become as important to serious cyclists as recording time and mileage was 15 years ago. We have chosen Power-Tap as a system because it provides a complete platform of vital information, yet offers simplicity in design and operation."
Power-measuring devices have been around for a few years, but the Power-Tap, launched by original developer Tune in 1999, was the first successful device aimed at regular consumers as well as sports science labs.
Graber Products, of Madison, Wisconsin, is also the parent of CycleOps fluid trainers, which the team used exclusively during the 2001 season and will continue to use in 2002.
More information: Power-Tap's website
A couple of weeks ago Cyclingnews reader Larry Malavear asked us why so many bike builders were going to 'Integrated' headsets. While some of the pros and cons of these systems are fairly obvious (pro: clean lines, a little less weight; con: yet another component standard), we thought we'd ask a few of the manufacturers who are using integrated and zero stack headsets why they're doing so.
Dave Cash of Litespeed was the first to get back to us: "This system provides a lighter frame/fork combination with added stiffness. Our use of the larger head tube lets us geometrically enhance the tube to an aerodynamic shape as well. We have used 1 1/8 for the past two years with great success. The lighter weight that the internal system offers was the next logical step. A last bit is the ease of serviceability this system has is a snap. Bearings can be replaced by just dropping them in."
On the other hand, the folks at Gios are disarmingly skeptical, telling us:
1) We will use the integrated model 1 1/8" only in one model named "Carbon".
2) In our opinion the use of integrated head set is chiefly due to an optical/fashion reason.
For 'optical' we think you can read 'visual' there (and we wish our Italian was as good at their English, or indeed extended beyond 'dopia ristretto').
Cane Creek, a company that makes both old-style external headsets and two types of integrated headset, sent us some very useful info on the types and standards. As Dia-Compe, Cane Creek was the company that introduced the threadless headset to mountain bikes back in 1990, an idea that took a couple of years to really take off but has now become the standard.
Cane Creek points out that there are actually two varieties of what you might call 'internal' headsets: 'Zero Stack' and 'Integrated'. Zero Stack headsets use 44mm diameter cups that fit into the head tube to mount the bearings, whereas an Integrated system mounts 41mm diameter bearings directly into the head tube.
And because the bike industry is like the computer industry (it loves standards so much it has loads of them) there's a third variant: Chris King's Perdido headset, which is similar to the Zero Stack headset but has 44.5mm diameter cups that fit deeper into the frame.
Picking apart the various aspects of these designs, lets take a closer look at the pros and cons.
Going from a 1in to a 1 1/8in steerer tube brings most of the advantages Dave Cash mentions: a torsionally stiffer steerer that can also be made lighter because the increased size allows the use of lighter materials like aluminium and carbon fiber.
Losing the steerer threads means that a headset can be field-adjusted with just an Allen key (or two, if the product manager has been annoying enough to spec a stem that uses a different size bolt from the top cap).
With any of the internal systems you no longer have to take the stack height of the headset into account when designing a frame, which makes it easier to build very small frames for shorter people. However, this makes very little difference to an average height male rider, who'll probably just find he gets a slightly longer head tube out of the deal.
Downsides include a bigger head tube, which may not be to everyone's aesthetic taste and which may put back some of the weight lost in the fork and headset itself.
The Integrated design also requires that the inside of the head tube be very accurately machined, since the bearings sit directly in it. Part of Chris King's rationale for the Perdido design, which uses easily-available cutting tools to shape the inside of the head tube, is that shops don't have the tools to work on frames that take 41mm Integrated headset bearings. If the builder hasn't cut the head tube correctly, then you have a problem, according to King.
However, that's true to an extent of all headsets -- they work better if the cups are correctly aligned, and shops routinely ream head tubes to improve the fit of the headset. Integrated headsets are just a bit more sensitive to alignment, a good reason to choose carefully the company that makes your frame.
The bottom line, so far at least, is this: Internal headsets weigh a bit less and look good, especially if you like designs that appear to meld frame and fork into a seamless unit. Adjustment and maintenance of some systems are easier than with 1in threaded headsets, and bearing replacement is a doddle. If the bearings fit straight into the frame in a fully integrated system, have your dealer make sure they fit correctly.
Chris King's website
After last week's tech letters we got lots of emails about the unusual 10g carbon fiber bottle cage that Don Marcopulos wrote to tell us about. One message was from the maker, Bernhard Langerbein of Bike Tuning Parts in Germany.
It turns out these cages are designed to use bottles with a slight taper (that answers the question "how does the bottle stay in the cage?") and Bernhard adds: "I sell the cage always with TAXC-Splash bottles and alloy screws. But here in Europe there are some other companies that now make "konic" bottles like Polysport, Toto, Cobra." Bernhard's website is currently only in German, but he's promised an English version soon.