Re: [CR]Oversize tubing - who did it?


Example: Framebuilders:Dario Pegoretti

Date: Fri, 26 May 2006 19:37:48 +0100
Subject: Re: [CR]Oversize tubing - who did it?
From: Hilary Stone <hilary.stone@blueyonder.co.uk>
To: Jan Heine <heine93@earthlink.net>, <classicrendezvous@bikelist.org>
In-Reply-To: <a05210600c09ce5b1b5c6@[192.168.1.33]>


I can answer one or two questions of Jan's and fill in on other issues he raises. Frame tubing diameters were pretty much standardised in Britain before WWI with 1in TT and 1 1/8in ST and DTs. After WWI Chater-Lea introduced (i think 1922) a lugset to build frames with a 7/8in TT and 1in DT and ST. Brampton followed suit soon afterwards. CL also supplied tubing to suit - I can look up the wall thicknesses if anyone is interested. These never proved very popular judging by the number of surviving bikes with 7/8in and 1in tubing ... unless they were a lot less reliable. By 1938 sets of tubing in this size combination were no longer available - in reality I think the idea had died a death by 1930. In the cycling press of the time there is a lot of talk on the importance of frame rigity and the smaller tube sizes ran completely contrary to that. Taper tubing was patented in Britain in 1925 by Granby; it is said that Maurice Selbach also played a part in the design. The first taper tubing was manufactured by Accles and Pollocks, Reynolds started to make taper tubes in the early 1930s. A 1938 Brown Bros catalogue gives the spec for the A&P tubes and Reynolds HM taper tubes:

A&P TT 7/8 to 1 1/8in 22g, DT 1 to 1 3/8in 22g, ST 1 3/8 to 1 1/8in 22g

Reynolds HM TT 1in 24/20g DB, DT 1 1/8 to 1 3/8in 22g, ST 1 3/8 to 1 1/8in 24g

After the taper gauge tubing patent it 1925 Granby offered the taper tubing to the rest of the cycle trade. Hence taper tube frames were built by most of the lightweight builders in the UK though some definitely built a lot more than others - Granby and Selbach being I think the most prolific.

Bates were not the first to use tubing with OS centres a small firm in S London announced the idea in 1933 - one wonders whether Bates bought the idea, pinched the idea or simply came up with the same idea themselves... However the Cantiflex tubes with OS centres work extremely well on TT and DTs - with both tubes the stresses are mainly torsional and the stresses are therefore at their highest near the centr point of the tube.

In Britain otherwise tube diameters were otherwise very standardised; tandems used larger OD tubing but that was also just to one standard.

Front end frame geometry is a complex subject Tony Oliver's Touring Bikes is about the best in the subject and my interpretation of Herse touring geometry is that they used geometry similar to that now used on tandems for touring so that there was less effect by lean steering - please correct me if I am wrong, Jan. I can certainly understand that my Thanet Silverlight leans strongly in that direction with less trail and greater fork offset. Despite skinny 1in tubes for TT, DT and ST it steers very nicely though not especially precisely. But mine is relatively small at 22in (CTT). On large frames riders are often less enamoured of a Silverlight's handling properties - there is simply too much flex then.

One small final point, Reynolds did make HM tubing in very thin gauges (24/26g I think) available in Britain (HM was introduced in 1933 despite what the incorrect history on the Reynolds website says) but frames built with this are almost unknown nowadays suggesting either a lack of popularity or a very poor survival rate.

Summing up in Britain from the 1920s through to the 1980s almost all bikes with the excveption of a very small minority were built with std diameter tubes. I've never heard of any experimenting outside of the 1 1/8in TTs - this was probably due the lack of lugs being available in any other sizes.

Hilary Stone, Bristol, Britain


> From: Jan Heine <heine93@earthlink.net>
> Date: Fri, 26 May 2006 10:30:50 -0700
> To: classicrendezvous@bikelist.org
> Subject: [CR]Oversize tubing - who did it?
>
>> I think it is reasonable to assert that mountain bike needs lead to some
>> important experimentation and the re-discovery that you can make a lighter
>> stronger frame by increasing the diameter of the tubes. It is fundamental
>> mechanics theory but long overlooked/ignored/unknown by the craftsman
>> builders.
>>
>> Todd Teachout
>> Hercules, CA
>
> Todd,
>
> From a 1970s perspective, I think you may be right. The lovely racing
> bikes of that era were all pretty similar, and lacking innovation.
>
> However, if one goes back in time, there was a lot of experimentation
> with tubing diameters - and I don't mean the super-skinny tubes of
> American department store bikes!
>
> To get some data, let's compile a list of the makers who experimented
> with oversize tubes on single bikes (let's not include tandems for
> now. Here is a start:
>
> - Bates: Cantiflex tubing was OS in the middle, but standard diameter
> at the ends.
> - A. S. Gillott: Tapertubes were OS at BB end
> - Herse: 30 mm OS down tubes on request (appear to have been thinwall.
> - Singer: singles built from OS tandem tubing, found to be
> harsh-riding and not much fun according to Ernest Csuka. Tandem
> tubing has relatively thick walls.
> - Schulz in 1930s France used a very OS central tube. The design
> apparently inspired the Paris Galibier (which added two very small
> diameter top tubes).
>
> Who else? Anybody in Italy? If somebody knows, the wall thicknesses
> of Bates' Cantiflex and Gillott's Tapertubes would be of interest,
> too.
>
> I think assuming the craftspeople building bikes in the old days were
> ignorant is a bit arrogant. Many of them worked with serious riders,
> who gave excellent feedback, and they put a lot of thought into their
> machines. The bigger makers - sure, I am willing to believe that
> there wasn't much analysis going on there. But people like Gillott,
> Herse, Bates and others had a very good grasp on things - certainly
> more so than many of the early mountain bikers, who started with
> junky bikes and could not build upon much of a cycling culture.
>
> When we don't understand something, we often assume it was done
> without much thought. The same applied to the front-end geometries of
> old French bikes. If you believe that "more trail = more stable
> handling," their geometries make no sense at all. I remember a post
> by an "expert" on the framebuilders' list claiming that "they didn't
> think much about front-end geometry back then."
>
> However, after much study and analysis, we found that nothing could
> be further from the truth. Especially Rene Herse bikes clearly had a
> front-end geometry adapted to their intended purposes. In fact, Peter
> Weigle recently told me about the front-end geometry he plans to use
> for his next "sportif" bike. It came as little suprise that it
> exactly matches that of a 1951 Rene Herse sportif (Peter did not know
> what geometries Herse used on his sportifs). Both bikes are intended
> for the same purpose and the same tire size... Once you understand
> the complex dynamics involved (low-speed vs. high-speed stability,
> weight of handlebar bag, pneumatic trail, etc.), you realize that
> there was a lot of thinking behind it. You may disagree, because you
> prefer a bike to handle or feel different, but that does not mean
> they were ignorant when they did what they did.
>
> And a final note regarding the viability of OS tubing: The often
> quoted 50:1 rule for older steels really makes little sense. Reynolds
> offered (in France, not in Britain) 531 in 3/10 mm wall thickness.
> For a 28 mm down tube, this comes out to a ratio of about 1:93. Sure,
> Those frames were fragile, especially when dented, but many held up
> for years of hard riding. Tours de France were won on them - for
> example, Ocana's Gitanes were reported to be made of the stuff.
>
> For comparison, a modern 1 1/4 down tube in a 0.4 mm wall thickness
> had a ratio of 1:79. So I don't see a reason why the same steel that
> could be made into 0.3 mm wall standard-diameter tubes could not be
> made in 0.4 mm OS tubes. So it was less a question of "could not be
> done," but "would not be done." I doubt it was ignorance. I believe
> it was that they tried it, and at the time, they preferred standard
> diameters. Times have changed, riding styles, distances, components,
> road conditions. All these factors influence the feel we want in a
> bike. So OS may make sense now when it did not decades ago.
>
> Jan Heine
> Editor/Publisher
> Vintage Bicycle Quarterly
> c/o Il Vecchio Bicycles
> 140 Lakeside Ave, Ste. C
> Seattle WA 98122
> http://www.vintagebicyclepress.com

>

> --