Author Topic: how does Campagnolo automatically detect the teeth on the bicycle sprocket?  (Read 1884 times)

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Offline DiTBhoTopic starter

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50 minutes ago I was shocked at what I saw!

On my street corner I was all busy replacing the inner tube because some hipsters must have been drunk enough to leave thumbtacks lying around, when I saw a road bicycle parked near me, and its Campagnolo computer able to auto detect the teeth on the sprocket and show it on the LCD.

A serious rider shifts and picks gears by feel and intuition, and there is no real need to have indicators, what matters in the end is the cycling cadence, the number revolutions per minute that bike crankset / pedals spins. The actual selected gear is secondary.

Even because the gearing is continually adjusted up or down to maintain the optimal efficient cadence for the cyclist in question for the current terrain, pace and desired level of effort.

So, for this reasons, road bikes do not include unnecessary features, for the most part, but ...
... technically WOW, is it science fiction? How can it be? :o :o :o

Unfortunately, I don't speak French .. I couldn't make any interview to that lucky owner.
« Last Edit: August 25, 2022, 10:53:25 am by DiTBho »
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Offline dave j

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I suspect it doesn't automatically detect the number of teeth on sprockets. The Campagnolo bike computer has wireless connection and there is a MyCampy app that lets you specify the exact bits you're using on your bike.
I'm not David L Jones. Apparently I actually do have to point this out.
 
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Offline DiTBhoTopic starter

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Ahhhh so it's a trick  :)
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Offline wn1fju

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Typically there are wireless transmitters in the two shifters on the handlebars that send data to the bicycle computer.  Once you tell the computer your rear gear cluster range and the front chainring sizes, the computer can display what you have selected from the internal positions of the shifter mechanisms.  This kind of stuff has been around for several years...

But I agree with you.  I can usually tell pretty accurately from my workload what gear I am in and don't really need a cycle computer to tell me.  Besides, you can always simply tilt your head down and look at the gears!
 

Offline thm_w

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There is some new obsession with head units recording: what gear you are in, what ratio, how many shifts you made, when you made them.
Most of it is just to say "hey we have a new feature, you'll have to buy the 2022 head unit to get it".
Maybe some fraction of people have use for it when training, should shift earlier here? who knows.

The more interesting aspect to me is:
- Shimano/SRAM/campag all fix their electronic shifters based on the number of gears.
This is pure marketing decision, because what you have inside the shifter is a small geared motor that is being told to move a certain distance when a shift signal is received (essentially).
On a 10 speed cassette it might be 3.95mm on 11 speed 3.7mm. Its a variable in the code somewhere.

A Chinese company decided on their model instead to let you enter that information yourself. So you can set 7 speed, 8 speed, 12 speed, whatever.
https://www.youtube.com/watch?v=eISsqEf3r7k

Now, the reliability of it is probably crap currently, but, at least they are fighting back against this idea of "must buy all the latest parts" to be compatible.
« Last Edit: August 25, 2022, 09:41:05 pm by thm_w »
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Offline timenutgoblin

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On my street corner I was all busy replacing the inner tube because some hipsters must have been drunk enough to leave thumbtacks lying around, when I saw a road bicycle parked near me, and its Campagnolo computer able to auto detect the teeth on the sprocket and show it on the LCD.

More than 10 years ago, Shimano released a bicycle computer called the Flight Deck SC-7900 with a gear display. I don't know exactly how it worked, though.

https://youtu.be/YIFP1ZMRUdU
 

Offline thm_w

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Flightdeck has wires going off to the left and right shifters, they have to be compatible: https://www.amazon.ca/Shimano-SM-SC70-Flight-Wireless-Bracket/dp/B000F5HXPU

So it could be like the swipe contacts in a multimeter, because it has to know the absolute position of the shifter (angle of the toothed cog inside). Can't quite tell from the photos.
Probably a reliability nightmare.

https://www.bikeforums.net/road-cycling/540563-what-shimano-flight-deck-what-flight-deck-compatible.html
https://www.bikeforums.net/general-cycling-discussion/1068371-what-flight-deck.html
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Offline Someone

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On my street corner I was all busy replacing the inner tube because some hipsters must have been drunk enough to leave thumbtacks lying around, when I saw a road bicycle parked near me, and its Campagnolo computer able to auto detect the teeth on the sprocket and show it on the LCD.

More than 10 years ago, Shimano released a bicycle computer called the Flight Deck SC-7900 with a gear display. I don't know exactly how it worked, though.

https://youtu.be/YIFP1ZMRUdU
At least 23 years:
1999 7702
Flight Deck cyclecomputer.
How did it work?
https://forum.cyclinguk.org/viewtopic.php?t=124594
Binary coded switch in the mechanical lever which reported the selected gear (not the gear currently engaged) just as the mechanical indicators did/do:
https://bike.shimano.com/en-AU/technologies/component/details/optical-gear-display.html

Flight deck's main feature was to report cadence from wheel sensor data rather than needing another sensor for the crank. The buttons on the hoods were convenient if you were "playing" with the computer on the go.
 
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Offline CatalinaWOW

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I never got good enough to automatically select gears.  Easy enough to change up and down through the sprocket range, but since the ratios from the chain rings overlap so much any time I changed the ring there was a period of hunting for the right sprocket gear.  A single lever system that picked equally spaced overall ratios would have really appealed to me.  Even better two levers, one to bump up/down one gear and another to bump up or down say five ratios fort those rapid changes needed at the tops and bottoms of hills.  Never saw anything that seemed both light and reliable.
 

Offline thm_w

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I never got good enough to automatically select gears.  Easy enough to change up and down through the sprocket range, but since the ratios from the chain rings overlap so much any time I changed the ring there was a period of hunting for the right sprocket gear.  A single lever system that picked equally spaced overall ratios would have really appealed to me.  Even better two levers, one to bump up/down one gear and another to bump up or down say five ratios fort those rapid changes needed at the tops and bottoms of hills.  Never saw anything that seemed both light and reliable.

Yeah, thats becoming more common now. You have a single lever and 10-12 somewhat evenly spaced gears. Makes it way more intuitive.

Levers depend on flat or drop style bars, with some drop bars you can downshift (easier gear) one or two gears at a time.
With some flat bar shifters you can go down four gears at a time, and up two at a time. To shift two you push the lever further on those. Depends on the model and brand though...

https://youtu.be/bRvRL4ZkD-Y?t=85
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Offline Someone

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I never got good enough to automatically select gears.  Easy enough to change up and down through the sprocket range, but since the ratios from the chain rings overlap so much any time I changed the ring there was a period of hunting for the right sprocket gear.  A single lever system that picked equally spaced overall ratios would have really appealed to me.  Even better two levers, one to bump up/down one gear and another to bump up or down say five ratios fort those rapid changes needed at the tops and bottoms of hills.  Never saw anything that seemed both light and reliable.
Part of this is that the gear ratios aren't designed for convenience or ease of use but for racing, the overlap was intentional for 2 reasons:
racers want to always have spare up/down gear or two at a moments notice without the slow change of the front
some chains cant bend enough to use the full width of the rear gears

So the shift between the front gears had to be matched with 3-6 "shifts" in the rear which would vary depending on both the specific ratios assembled/setup and the to-from gear ratios in use. As mentioned above, its only the newest electronic shifting sets (also eyewateringly expensive) that now enable it to be seamless (fast) enough that a single up/down control is possible....
Which reached the market at almost the same time as wide range 1x (only single gear at the front) specific rear gear clusters, so for the "normal" around town rider there are two good options:
gear hub (the price puts some people off)
1x11/1x12 with a 1:4 range or higher
 

Offline DiTBhoTopic starter

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I never got good enough to automatically select gears.  Easy enough to change up and down through the sprocket range

I don't do any climbs because I have a back problem, long journeys but all in the plains, I noticed I am using the same setup 52 { 13, 15, 17}

Only and always the same gears
- tours within the city, 52-17
- urban stretches, 52-15, 52-17
- extra-urban stretches, 52-13
- stretches along the sea or lakes, 52-15

speed between 27 and 35Km/h, low rpm, old steel-frame bicycle, Campagnolo Mirage 1992

I cannot do the same with any Pinarello Prince, Paris, Razha (worse still with my Monza Wr) with Shimano Ultegra bloody thing, they have a completely different gears-setup, and I have to continuously shift up and down like a deranged dog on speed because I never find the optimal ratio.
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Offline DiTBhoTopic starter

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Which reached the market at almost the same time as wide range 1x (only single gear at the front) specific rear gear clusters

Single gear at the front looks like what nowadays they call Gravel-profile, optimized for long travels (>200Km) and comfort

I am more for Endurance-profile, optimized for short travels (<150Km) on 32Km/h average speed with a bit of comfort

Decathlon has some interesting bicycles, but no gear-hub.

gear hub

Can you convert a vintage bicycle into gear-hub? 3 speeds would be OK for me.
1x3 :o
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Offline thm_w

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The point of having easy gear ranges is that you can put the same low effort into climbing as riding on the flat :)
https://www.youtube.com/watch?v=ipENw5mjjSg
But I might know what you mean, it seems to engage the back muscles more than flat riding.

You can convert any bike with a standard quick release dropout spacing of 127-135mm to a nexus gear hub. Don't really know if its worth it though.
https://www.sheldonbrown.com/nexus-mech.html
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