Aardwolf

Hiya Folks,
I've been looking at early Holdsworths (50s - 60s) and I've been wondering what was going on with head/seat tube angles.

(https://www.nkilgariff.com/HoldsModelPages/Cyclone.htm)
Cyclone 1961(https://www.classiclightweights.co.u...-f-holdsworth/)
1954 MonsoonSo it looks like 71/73 was normal and 72/72 was "massed start".
My 1982 Avanti is 73/73, 1982 Mistral (touring) is 72/72.

I've got some idea of what a "massed start" was but I don't understand why it required different angles,
and why 73/73 is now normal.

Trakhak

As I understand it (from reading bike magazines in the US when I started racing, in the mid-1960s), time trialing was the major focus of bike racing in the UK in the 1950s and into the 1960s. That being the case, a time trial-specific frame would feature a steeper head tube angle paired with a shallower seat tube angle, resulting in a long top tube and enabling a flat-backed, aerodynamic position for time trialists riding in the drops/hooks.

Massed-start racing was generally referred to as "road racing" almost everywhere outside the UK in those days. I guess the parallel 72-degree angles for the massed-start frames made for a slightly more heads-up riding position and thus safer maneuvering in the pack.

The standards for racing bike frame geometry have gone through a number of evolutions since the mid-20th century. Those time trial and massed-start angles were a bit steeper than they would have been some years earlier, reflecting the gradual increase in the number and extent of improved (paved) roads in Great Britain (and Europe).

Thereafter, frame angles continued to steepen gradually. Going into the 1980s, Italian road racing frames in particular were approaching the same dimensions as track bikes, probably reflecting the greater emphasis in Italian racing on sprinting over endurance. But the most extreme example of the steeper-is-better philosophy may be that of the late-'80s Cannondale Criterium-geometry line of racing frames, designed with input from Davis Phinney, arguably the premier American sprinter of the era. Those bikes really were essentially track bikes with derailleurs and brakes added. (If you ever wondered where Cannondale got the reputation for making "harsh-riding" bikes, look no further than the Crit Series.)

The current 73-degree-ish seat and head tube angles reflect the realization that the bikes with the steepest angles didn't make the riders any faster and were more taxing to ride.

Interesting topic. At the risk of derailing this thread, I hope someone with more knowledge will weigh in, especially about the racing scene in Great Britain back then. For instance, is it true that the major British bike racing sanctioning body would ban cyclists from official time trials if they joined the breakaway massed-start racing organization (i.e., the National Cyclists Union versus the British League of Racing Cyclists, or was it the British Cycling Federation)?

Aardwolf

Cheers,
I was wondering how 'massed start' differed from road racing - they're the same thing (only foreign).

It's certainly true that there was opposition to mass start races - the Nation Cycling Union banned participants in 1951.
This is a good read: https://allezallezcyling.wordpress.c...n-to-holyhead/
and it's where the British League of Racing Cyclists started.

Trakhak

Thanks for posting that link! Anyone with any interest at all in UK bike racing of that era will enjoy it.

63rickert

71/73 is going to have toe overlap issues unless the top tube is very long. A time trialist who believes in 71 degree seat angles is not going to care about that. The belief in shallow angles (guessing here) would be from tradition.

Time trialists then and now are totally geeked out over mechanical trivia and oddities. The 72/72 bike is going to be way more useful.

Bad Lag

This quote is from the brochure.

"Frame built with a semi-straight head for free steering at speed giving perfect control;..."

Please, tell me,

• What is a "semi-straight head"?
• Is there such a thing as a fully straight head or a crooked head?
• Do other designs not allow for "free steering"?
• Does this design only give "free steering" only when "at speed"?
• What is "perfect control"?
• Why wouldn't one want "perfect control" at all speeds and not just when "at speed"?

I'm not being sarcastic here. My questions regard the design of bicycle frames, about which I am trying to learn.

rhm

+1

dddd

Interesting numbers reversal, as my very-British Super Course and Grand Sports models both feature identical 71-degree head tube and 73-degree seat tube angles in the 23" size.
CX or "gravel-bike" geometry in other words!




Also interestingly, my early-1950's E. Christophe road bike features frame angles north of 76 degrees in the 56cm size!




A steeper HT angle, in combination with a longer stem, allow a rider to more safely draft a leading rider without touching tires, which is worth a good number of watts of needed rider output. This combination also puts greater weight on the front tire for better steering stability, but may result in toe overlap in smaller frame sizes.
A steeper head tube angle also tends to be combined with less fork rake to maintain trail and thus stability, further shortening the front-center for even less toe clearance.

Different road frame geometries are and always have been re-visited, but today's seat tube angles in frame sizes around 55-58cm seem to run close to 73.5 degrees.
Today's HT angles for road frames in this same size range seem to run at 72.5 to 73 degrees.
My mid-1980's Holdsworth Special is set at 73X73 in the 23" size.

Kilroy1988 

I'm not going to comment on this specific bicycle or design but having read straight through several dozen period British cycling magazines and dozens more brochures and free-standing advertisements, I can tell you that superfluous marketing language was not an unusual stratagem to be deployed by frame builders of the time. I wouldn't hold too much stock in trying to interpret that line, which appears to be a lazy attempt at making a certain detail seem unique and decisive when it really isn't all that much.

-Gregory

Doug Fattic 

One of the things that surprised me the most when I went to learn how to build frames in England in 1975 was how little their blue collar workers were paid. The typical cyclist made very little money. My high school teacher's salary at the time was around $8,000 a year (10 months) and I was vastly more wealthy that most of those I knew over there. Few had cars, so their bicycle became a multi functional tool for all kinds of travel requirements. This effected how their bicycles were designed. They didn't do pack racing, it was almost all time trialing. A bicycle was a big expense and had to be very multi-purpose.

A 71º seat angle is sensible for general purpose riding. Your body weight is better balanced over the pedals taking your upper body weight off of your arms and hands. When you are using your bicycle for basic transportation you sit a bit more upright so you can look down the road easier for any danger issues. The more upright one sits the more they want their seat to go back. They usually had longer top tubes combined with shorter stems that made for better handling if using a handlebar bag. Americans are attracted to go fast bikes even if that isn't what is best for their kind of riding. Company lawyers in the US demand a steeper seat angle to get the front wheel out of the way of the rider's toes

There is almost always the assumption that over the years we have made improvements in bicycle design but in reality we just have different requirements for a different culture and bicycle usage. .

Aardwolf

Being an old git I'm tending towards a slightly more upright riding position,
so it sounds like 71º seat angle would be good for me.

I just need to look out for toe overlap (23" frame) and do some more research.
The top tube was 22.5" on the 23" frames (https://www.nkilgariff.com/HoldsCats...Cyc_Zeph61.htm)

On the other hand, it probably mostly depends what comes up on Ebay first

63rickert

I would agree that a 71 seat angle is sensible for general purpose riding. But these were explicitly time trial bikes.

Also agree with the line about lawyers dictating seat angles for US market bikes. What happens next is everyone on the receiving end of those dictates starts inventing reasons why everything is for the best in the best of all possible worlds and really there is no alternative. The way things are is the way they have to be.

Very often frame design makes no sense. It can be explained but explanations are just that, the design is not perfect, it just has reasons. Tradition weighs heavy. What peers and colleagues are doing weighs heavy. For cyclists in 1950s UK who still saw DL-1s with 66 seat angles daily, and maybe owned and used one, a 71 seat angle would have looked racy enough. Add a 73 head and it looks totally racy. The 73 head was likely combined with a long rake fork. It was not that they wanted low trail bikes, or that they were influenced by French randonneurs. They simply made the head steep and got around to making a shorter rake fork a couple decades later. On bigger frames the long rake would also keep the toes out of the front wheel. Maybe. Small frames not a chance.

Now add in most in UK used mudguards all the time and only took them off to race (in a time trial). Lots of negative clearance. That it took decades to change that is not surprising.

Handlebar bags? Brits use saddlebags. Bottle cage goes on handlebars.

Bad Lag

Mine is a British bike - Bob Jackson, Leeds, England.

I have massive toe overlap. Super tight turns at near zero speed, such as when starting off, can be tricky because of it. This is when you do actually turn the wheel a significant amount.

Honestly, it just isn't an issue. In the 50 years I've had it, I have had "toe strike" maybe a dozen times but have never fallen as a consequence.

At high speed, you just do not turn the wheel very much, at all. As turns get tighter and higher in speed, I tend to stop pedaling, weight the outside pedal and lean the bike over - it's not a wheel turning thing. Besides, with momentum at high speed, touching a tire would be akin to braking. It's not a pump thru the spokes kind of thing.

It would be interesting to see the frame geometry required to provide positive clearance for someone with feet as BIG as mine, or bigger.

clubman 

Well, as someone with long arms, short inseam and big feet, I can tell you that all of my performance 'speed' bikes have had toe overlap. Similarly, I've never been able to worry about top tube clearance for the same reasons.

Seriously, it's no big deal, you adjust to the bike and you're no more likely to fall or hurt oneself than anyone else.

Aardwolf

I just checked my 1982 Holdsworth Avanti (22" frame, 73/73 degrees) and there's about 1cm gap between the toe clip and the front tyre.
But I believe you, I've been searching on toe overlap and nobody says it's a real problem.

Bad Lag

I also checked (but only measured by eye). Mine has about 2" of overlap with the toe clip.

It's totally fine.