Hi All,
Joel Greenblatt of Clockwork Bikes has posted his latest photos from the North American Handbuilt Bicycles Show (NAHBS), currently in-progress in Sacramento, California (March 2nd-4th, 2012). For show site, see:
http://2012.handmadebicycleshow.com/ . Joel's Flickr photostream is available in its entirety at:
http://www.flickr.com/photos/28879558@N04/The photos are uncaptioned and all drool-worthy, but relevant to this category are the photos of a nice cutaway of a Rohloff Speedhub. I would suggest right-clicking the photos at the links below and selecting the "Original" view for the full impact. The Rohloff cutaways are preceded by some nice views of a Schlumpf Drive. See:
Rohloff Cutaway
http://www.flickr.com/photos/28879558@N04/6802263472/in/set-72157629499390397/http://www.flickr.com/photos/28879558@N04/6948374735/in/set-72157629499390397/http://www.flickr.com/photos/28879558@N04/6802263654/in/set-72157629499390397/I am struck by how remarkably thin the shell is. Take a close look at the several sharp radius changes, which would seem to create stress risers at several points in the shell, yet there have been no reported failures there. The flanges -- where occasional breakages have been reported -- look to be entirely conventional in design and conformation. I think flange breakage (when it rarely occurs) is likely due to 1) variations in density (porosity) of the billet pour, 2) the fact the hub shells are not forged (and have no aligned grain structure) and 3) their large diameter results in a more acute lateral pull-to-center as the spokes enter the rim at a more acute angle (regardless of how the rim holes are aligned). Given the low incidence of failure, my money is each of these in turn, with 1) being the precipitating cause, aggravated by the other two.
Schlumpf Cutaway
http://www.flickr.com/photos/28879558@N04/6948374397/in/set-72157629499390397/http://www.flickr.com/photos/28879558@N04/6802263374/in/set-72157629499390397/----------------------------------------------------------------------------
Off-topic, but other um, highlights from the show include...
- a bicycle with a faux chainsaw chain; ouch.
Definitely needs a chainring guard:
http://www.flickr.com/photos/28879558@N04/6802262396/in/set-72157629499390397/- a variety of single-chainring chainkeepers from Paul's:
http://www.flickr.com/photos/28879558@N04/6802261600/in/set-72157629499390397/- a Really Bad (from an engineering standpoint; maybe the frame materials absorb some of the stress?) dropout-stay interface on a bamboo-framed bike:
http://www.flickr.com/photos/28879558@N04/6802261398/in/set-72157629499390397/- painfully sharp cantis on a Bruce Gordon (sharp-pointy stuff is Big this year...):
http://www.flickr.com/photos/28879558@N04/6802259648/in/set-72157629499390397/- Schmidt dynohub with Schmidt conductive (no external wires) fork ends:
http://www.flickr.com/photos/28879558@N04/6801915090/in/set-72157629499390397/There's enough here to keep any bikie busy for awhile, but I will observe how nicely Thorn's designs -- tailored for the practicalities of mass-production -- come across against full-on, cost-no-object handmade custom bikes whose builders' imaginaitons have run wild. There are a lot of nice design features on Thorns also seen among the bikes at the NAHBS, things like hidden or filled vent holes, pump pegs on the left seatstays (a la Sherpas) and bi-plate fork crowns (as on Ravens and Nomads).
Best,
Dan.
