Tour de France tech question

[Andy in Germany]

Elder son should get points deducted for the parental assistance!

We argue that he should have points added for bilingual research, so it works out even.

 

[Ajax Bay]

When did Aluminium replace steel,

Alu frames probably began to appear regularly in the late 90s.

Not disagreeing (and 'out of time').
My 1981 Alan (owned since '83) is aluminium; glued and screwed. Still riding well, but main bike is steel.

 

[Stompier]

Not disagreeing (and 'out of time').
My 1981 Alan (owned since '83) is aluminium; glued and screwed. Still riding well, but main bike is steel.

Indeed. I used to want an Alan frame back in the day - right up until the point where I saw one snap in half

I think I said on another thread that the first aluminium bike frame was actually made in the 1800s, but certainly from a pro-team point of view, you didn't see them regularly until the mid/late 90s.

 

[BalkanExpress]

Could be, but from what I've read these were probably a bit before his era - the stories in question were 1930s, and retro direct was more turn-of-the-century.


Campagnolo Corsa. Moved the whole wheel back and forwards to maintain chain tension. A beautifully bonkers design. I've read that they weren't all that popular with riders, but I love the fact that he's done away with the need for a chain tension pulley.


Good stuff! (edit: or should I say Herzliche Glückwünsche! )
Courtesy of google translate

Calling @Specialeyes , I know he is not the boasting type but I believe he has a Cambio coursa, a Paris Roubaix and a something else, so will be able to give us chapter and verse

 

[Specialeyes]

Calling @Specialeyes , I know he is not the boasting type but I believe he has a Cambio coursa, a Paris Roubaix and a something else, so will be able to give us chapter and verse

Hehe, thanks! The Both the Cambio Corsa and Paris Roubaix are 'pedal backwards / sliding hub' changers.

The Cambio Corsa ("Due Leve") came first, in 1946. The longer of the 2 levers acted like an extended quick-release, freeing the splined axle in the toothed rear dropouts. That's the moment to pedal backwards or you pull the wheel forwards out of the dropouts! (DAMHIKT)

The dropouts, as well as being toothed, are angled slightly so that the rider's weight keeps the tension in the chain.

The shorter lever is used to force the chain left or right across the 4-speed block. As it's ahead of the block on the upper side, it's pushing the chain across before the sprockets - you're pedalling backwards, remember! - which is the opposite of the paralellogram derailleur.

Once you're in the correct ratio, you just tighten the longer lever and pedal forwards.

The whole process takes about 2 seconds.

The range of the gears is determined by the fixed length of the dropouts, to a hearty six teeth! The most common ratios were 15-21 while mine was a 'relaxed' 17-23

Gino Bartalli won the 1948 TdF on a Cambio-Corsa bike. There's a famous photo of him changing gears on a steep climb (which will tell you how quick he got at changing gears, as remember he's not just soft-pedalling, but pedalling backwards at that point!)


The "Una Leva" ws introduced in 1949, and renamed Paris-Roubaix when Coppi won the 1950 edition. (Thus making Una-Leva versions, without the name Paris Roubaix rarer). It's works on the same basic principles, but has slightly longer dropouts and manages to incorporate both the quick-release function and the chain-pushing cage into a single lever. The first 90 degrees of its travel are the QR while the chain cage swings freely, then once a spring engages over a 'hump' the QR stops and the chain cage engages. All of this engineering magic is inside the bottle-shaped section at the bottom of the lever - you can see the chain cage is a separate section. The practical upshot is that you don't have to think about the QR. Just push the lever past 90 degrees while pedalling backwards, pick a gear, then return the lever to its starting position.

Although that's a masterful piece of engineering in itself, the thing that always blows my mind is that in the last few degrees of travel a tiny 'claw' engages and pushes on a gear running around the outside of the hub. (You can see it at the 12-o'clock position in the photo below). This little push only moves the axle about a millimetre forwards in the dropouts, but it is just the right amount to result in perfect chain tension. The earlier Cambio Corsa axle would remain forced just as far up the dropout as the rider's weight pushed it, meaning heavier riders could have over-tight chains. Absolute bloody genius.

Note to self - should make a video of this, it would be easier to explain!

Paris Roubaix remained in production into the 1950s, despite the fact that in 1951 Campganolo introduced the first parallelogram derailleur in the Gran Sport. Coppi's 1952 Tour and Giro victories were using Gran Sport, which probably sounded the death knell for the earlier, finger-slicing, madcap derailleur systems!

The 'something else' @BalkanExpress refers to is a Vittoria Margherita which is equally madcap, has the benefit of being easier to use, but is bulkier, slower to use in expert hands and has manually set chain tension so is prone to dropping the chain. You can pedal forwards to use it (though backwards also works), it won't catch your finger in the spokes and won't fling your back wheel forwards out of the dropouts if you misuse it. What kind of non-hardcore changer is that?

As the chain is pushed from side to side by a pair of paddles on the top of the chainstay operated by twisting the knob on top of the tension lever, it must make this the original 'flappy paddle gearbox', well ahead of Top Gear.

So I reckon @Dogtrousers is referring to one of the first two, as they're the proper back-pedal gear changes, and would definitely stick in the mind!

 

[BalkanExpress]

@Specialeyes

And for the wood rims.