The old saying “a chain is only as strong as its weakest link” has an analog in bike frames, and on metal bikes often times it is the area around the right rear dropout. Millions of bikes don’t fail at the dropout, but I’m never surprised when I see one break. Fatigue failures basically require two things to occur: a cyclical load on the structure and a focal point where the stress can overwhelm the strength of the material. A bicycle frame is a deceptively complex problem to analyze stresses, with a huge number of variables that are difficult to quantify. I suspect that the vast majority of dropouts in the history of bicycle design were designed with aesthetics and intuition in mind rather than detailed stress analysis. Accumulated experiences would be incorporated into new designs. By now, you’d think that the dropout would be perfected, but manufacturing methods, frame styles, and drivetrain components have continued to evolve. Setting aside the carbon fibre frame construction and the rapid onset of thru-axles, dropouts on metal bikes still fail too.
This first photo shows a fixed-gear/single speed bike with a fractured dropout. It is a steel bike from a somewhat niche yet inexpensive brand, a brand that has the wherewithal to have its own dropouts made rather than buy generic frame fittings. The brand’s marketing taps into the everyman appeal of traditional steel framesets, which is made accessible through the economy of Taiwanese manufacturing. The dropout design incorporates a practical integral axle tensioner bolt and stylized cutout windows beside the chain stay and seat stay attachments that harken to the delicate embellishments the framebuilders of yore added to forged or stamped fittings with much hand-filing labour. But these windows are not added by hand, nor is the dropout is likely stamped or forged. Most likely is investment cast, since modern manufacturing methods allow near-net shape items to be quickly developed and economically produced. However, cast steel parts frequently have less strength than forgings. In all likelihood, the strength of the material was just not sufficient with the windows removing so much metal in the area. Interestingly, the left dropout partially fractured in the exact same place. Basing statements on anecdotal evidence can be shady business, but I did see two more bikes with broken dropouts like this not long after. And current production of this model eschews the window cutouts adjacent to the chainstay, suggesting that the manufacturer felt compelled to change the design.
This morning on Sony Mirrorless Pro, blogged about the new Fuji X-Pro2 and welcome the completion in the compact-pro camera market. Also noticed the bike-related photos in Fuji’s 5th anniversary photo contest. Like this Tour photo
And dreamy urban shot
Worth nothing too how Fuji is emphasizing rugged toughness with outside imagery and this battered-hero image.
Also see fashion and BMX
Their mini site about the their AF technology also features more bicycle imagery – HELLO FUJI PR!
Expect the X-Pro2 to be welcomed by Fuji fans, as well as us, in our ongoing quest to travel lighter, smarter, and take better photos. The X-Pro2 body goes on sale for $1,699.95 next month at $400 more than the X-T1 from 2 years ago. It’s a premium pro compact camera targeting professional shooters, like the market Sony defined.
Working on the next issue of our magazine and riding around trying to find something to put on that rack…the one on the Trek Boone. This one
I’ll tell you more about what we’re doing with the Boone in the issue; as well as content from our contributors.