automatic gears on a bike ???

[mickle]

Nexus automatic about a decade back, Deal drive back in the 80s, doubtless a few others.
Bindun.

Yeah, the Deal drive! What an abortion. Interesting but fatally flawed - it was amzing that the designer couldn't see the obvious.

I entered a magazine competition to design the logo for that with the promise of product for the winner. My logo appeared on the later incarnations of it but I didn't see any product.

 

[mickle]

I can imagine a future for auto transmissions which would adjust your gear ratio (using CVT ideally) according to an adjustable cadence pre-set. Meaning the rider could adjust the desired cadence on the fly and the tranny would do all the rest.

 

[PpPete]

No way I'm riding the tandem with a tranny on the back....

 

[mickle]

meh

 

[bikepete]

As well as the electronic ones (Shimano did a relatively nice to ride four-speed IIRC) there have been several which use centrifugal weights to auto-operate a rear derailleur. Here's one:

http://www.landriderbikes.com/

http://www.youtube.c...h?v=iWOd_0BYm0U

Some amusing opinions on it e.g. here:

http://www.bikeforum...p/t-437895.html

A potentially nicer idea was the Browning system:

http://www2.bsn.com/...s/browning.html

But it never made it commercially.

 

[ASC1951]

would it be possible/practical to have automatic gear shifting on a bike?

What would be the advantage? You can see the point with a car because a) the optimum power range is narrow and b) the engine can't think for itself. All you would achieve with a bike would be to add weight.

 

[mickle]

What if it didn't add weight?

 

[iAmiAdam]

Then it'd achieve nothing.

Computers only know what you tell them.

Exactly my point, rather than go through a computer system why can't I just use the shifters I already have.







If it isn't broken, don't fix it.

 

[mickle]

eh

 

[mark barker]

What would be the advantage? You can see the point with a car because a) the optimum power range is narrow and b) the engine can't think for itself. All you would achieve with a bike would be to add weight.

I think it'd depend on who it was aimed at. I can see a market for it, theres plenty of people who ride because its more practical than driving, not because they enjoy it. For those riders a simple set up of pedal and go would be perfect.

 

[iAmiAdam]

None of this would be instant either, to detect the change in cadence it has to be measured over a few seconds, and what happens if you just top pedalling for a few seconds? does it try to shift to the lowest gear instantly.



In regards to Di2, there's no way that the team cars can change gears, it's not a wireless system.

 

[snailracer]

What would be the advantage? You can see the point with a car because a) the optimum power range is narrow and b) the engine can't think for itself. All you would achieve with a bike would be to add weight.

The optimum cadence range for a human is actually narrower than that of most cars, which can do 0 - 120 mph with only 5 gears i.e. 24mph per gear.

And there are people who just can't understand gears.

 

[mickle]

None of this would be instant either, to detect the change in cadence it has to be measured over a few seconds, and what happens if you just top pedalling for a few seconds? does it try to shift to the lowest gear instantly.

Depends on the number of sensors shirley?

The problem with the Deal Drive back in 1982 was that it was spring loaded. To get it into first gear from stationary (at rest = top gear) you had to pedal it. And it meant that the cranks would spring backwards when you took your foot off the pedal.

And the fact that it was in effect a hexagonal chainring didn't help.

 

[snailracer]

IIRC the "commuter" ancestor of Di2 was fully automatic. The automatic feature was removed when it made its way into race bikes.

 

[asterix]

The optimum cadence range for a human is actually narrower than that of most cars, which can do 0 - 120 mph with only 5 gears i.e. 24mph per gear.

And there are people who just can't understand gears.

cadence<>power