i'm replying to the snipped post below. 1) i don't agree with the article in velonews. i think it borders on 'paralysis by analysis'. if your bicycle shakes, it usually only shakes on one hill at one time. that is, it's not a day-to-day problem. personally, i see it as a momentary incident, one in which the rider's fore-aft shift came at an inopportune time. a poorly designed frame, or a rider on a frame that doesn't allow for proper balance, or a combination of both, 'could' be the culprit. i've seen all combos of head angles, rakes, front wheelbases, stem lengths...and there is no constant to the issue of shimmy. i think that notion of 'straighter' frames shimming more frequently than crooked frames is bullshit. ya' know what i think the real issue is? some people don't have balls. they don't know how to go down a hill without freezing up. period. i MEAN, do you ever here of guys descending in the pyrenees, in the pro ranks, on factory built bicycles...do you ever hear about these guys losing it at 62mph? no! because they have honed their bicycle handling skills. for the rest of us, when it comes to the issue of shimmy, and descending speeds, and the related issues, i say it's all pilot error. 2) i don't understand the description about the brazing technique sterling was referencing. i'll wait to read more about it. 3) the os tubing that the french were using was less than 1mm different. it was hardly oversize in the accepted use of the term. the same effect that you get from growing the tube's od that small amount could be had simply by increasing the wall thickness. 4) all my frames, except those specifically 'of the period', are fully oversized and have been for almost 10 years. materials improvements have allowed that the newer frames weigh less without the penaltys once associated with 'light' frames. as far as 'capturing the past' goes, that's not part of the commerce of it all. that is, the few folks that want a bike 'from the old days', but built in the here-and-now, don't constitute a market. yet. e-RICHIE Richard Sachs Cycles No.9, North Main Street Chester, CT 06412 USA http://www.richardsachs.com ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ <Sterling@tns.net> writes: A couple of ideas regarding frame building/construction came together for me in the past few weeks.
There is an interesting article in this months Velo News , which discusses the elements of front end shimmy. Shimmy , head shake , high-speed wobble is caused by top tube rigidity or lack of it.
His frameset was constructed so that the top tube and down tube , in addition to the brazing at the lugs , were also brazed inside the head tube.
The French so clearly understood the elements of front end shimmy , that their tube sets also included an oversized top tube. It is also known that Rene Herse built racing bikes with oversized down tubes for extra rigidity , and I believe I saw a Rene Herse Randonneur bike on Ebay last year that also had the oversize down tube treatment . I'm sure there would have been more of oversized tube sets , if builders/constructors did not have to make the lugs themselves to fit the oversized tubes.
I would like to hear from the frame builders/constructors on the
list as to what they think of these ideas ( tubes brazed to the head
tube; oversized tube sets). This best reason for not brazing the
tubes inside the head tube is all the extra work , only Rene Herse
and Alex Singer were willing to go the extra mile.
Would having builders like Baylis and Sachs build bikes
with oversized tubes ruin the attempt to capture the past with this
type of build? Any comments from others?
Sterling Peters