The constantly changing normal
Mon, June 7, 2021 
Giuseppe Martano 1934 Tour de France
Life is a constant change, new ideas, and new technology. People often hate change, they fight against it, but it is futile. Change will come for better or worse. In time we accept change, (Often we have no choice.) and a new “Normal” is established.
In the mid-1970s I wrote a series of articles on frame design for the British “Cycling” magazine. There was no Internet back then, no email, and no comments section where you could debate any ideas put forward. However, one older gentleman took the trouble to write and mail me a long hand-written letter, explaining my theories on “Trail” were wrong, and he enclosed a photocopy of an article from ‘Cycling’ dated 1946 to prove it.
Back in the 1930s, 1940s, and even into the 1950s, there was a thinking that trail was a bad thing.
It was thought that it made the steering of the bike sluggish.
Front forks had a rake (Offset.) of 3 to 3.5 inches. (76mm. to 90mm.) See the photo at the top, from the 1934 Tour de France, and the drawing, left.
I can even see where this idea gained traction.
At first glance it seems logical that the steering axis should reach the ground at the exact point the wheel makes contact and therefore turns at that point. Or it would make sense if a cyclist steered his bike by turning the handlebars, and the frame remained upright.
However, we steer a bicycle by leaning in the direction we wish to turn, and the steering axis ahead of the wheel’s point of contact, is one of the forces causing the wheel to turn in the direction of the lean. (See drawing below right.)
As far back as the late 1950s, early 1960s, I had realized that trail was a good thing, as had almost every other framebuilder. It provides a caster action, and gives the bike stability when going straight, and certain ‘self-steering’ characteristics into the corners.
However, trail goes hand in hand with the head angle. Steeper angles are more sensitive and need less trail to achieve the same self-steering qualities. As many framebuilders in the 1970s were building frames with 75 and even 76-degree head angles, their trail would have been a lot less than mine.
As well as staying with a 73 head angle with less rake, my overall geometry placed the rider’s weight more forward, which also affected the ‘feel’ of the steering. The point I am making, you cannot simply say fork rake should be this much, and trail should be this, without considering the whole frame’s geometry.
Whenever I write one of these type of articles the comments that follow remind me of the old gentleman that took the time to write me in the mid-1970s. He was quoting from an article written 30 years earlier in the mid-1940s.
Information here is just my opinion, if you read another article with a different point of view, it does not mean I am right and they are wrong, or vice-versa, it is simply two differing opinions. One must weigh the qualifications of the writers, and from the information, the reader forms his own opinion.
The problem is today there is an overload of information, couple this with a lot of poor quality and miss-information, and one often searches until they find an article that aligns with their own established viewpoint. This approach leaves little room for growth, instead of keeping an open mind and leaving room for new ideas.
There were more changes made in the 30 years that were the 60s, 70s, and 80s. than there were in the previous 60 or more years. Changes in actual frame geometry that is. Angles, tube lengths, and fork offset, etc. Closer wheel clearances, shorter wheelbases, and higher bottom brackets too.
Some changes brought about by economic factors, others by framebuilders trying to make something better. It once again made me realize how fortunate I was to have been around in that period. Those times will never happen again. There was so much experimentation going on amongst so many individual craftsmen. There will never be that many individual craftsmen at the same time again.
We have also seen many changes in the last 30 or more years since the end of the 1980s. The whole appearance of the bicycle has changed. We have seen clipless pedals, index shifting, leading to 11 (Or more.) gears. Thread-less headsets. Oversize tubes and carbon fiber have changed to look of the frame, along with sloping top tubes and tee-shirt sizing.
But actual frame geometry has not changed that much, 73/73 angles came out in the 1960s. My road bike fork rake was 35mm. I don’t think other steel framebuilders were too far away from that. Probably around 38mm. was an average. Fork rakes (Offset.) have increased but I feel this has more to do with avoiding toe overlap with the front wheel, than to affect the actual handling. I guess for the time being somewhat of a new norm has been established.
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Reader Comments (6)
Similarly, I still see plenty of articles claiming skinny tires are faster, when practical testing by Bicycle Quarterly has pretty much disproven the idea
Dave, I happen to own a frame that was part of those days of experimentation with geometries. It is an Alan aluminum frame and it is very upright with very little (25mm) rake, ending up with too much trail. As a result the bike is very skittish and to ride no-hands you have to sit on the very back of the saddle.
Does the seat post angle get steeper in smaller sizes? Also do you take the length of the thigh(hip socket to knee) in account in custom building?
thanks
Douglas,
On my frames yes, the seat angle got progressively steeper as the frame got smaller.
As for thigh length, if you have two or more people of identical leg length, (Inside leg.) If their thigh length is longer then it follows their lower leg is shorter and vice versa. The position of the knee is not that much different. And as one is pedaling in circles anyway, knee over pedal is less important. It doesn't matter if one is sitting back and pushing forward, or is over the pedals pushing down. One crank provides half the power stroke, before the opposite crank takes over.
Dave
Thanks. Went to a ball game with a friend of mine and as we sat on the bench seats with our backs straight I noticed for the first time that the two or three inch difference in our height was all due to thigh length which surprised me. I guess that would alter seat tube height(length) but also might mean that I was somewhat taller than average from the waist up. Don't know how that would work for the top tube as I have fairly short arms. Kind of seems like one could tie ones self in knots to get a correct design. I actually have two circa 1986 - 90 steel bikes. One a lugged steel and the other fillet brazed by a local builder. If you looked at them you would think they were not designed for the same person. Mainly, I think, because the fillet brazed bike wasn't tied to the angles required by the lugs. Also designed as more of a touring class rig.
In fact, there are very few changes in the frame or model. More parts are changes, but the ultimate aim is for humans to drive farther distances with less force.