Shifting direction is different for front and rear shifters

Question

I have been riding singlespeed and 1x setups for decades. The last time I had a front derailleur was over 30 years ago, and the shifter was on the downtube then, and I don’t have any memory of how it all worked. So I’m experiencing a time warp of sorts when it comes to multi-geared bikes.

Recently I bought a cargo bike (Mongoose Envoy) with a Shimano 3X drivetrain. I love having the extra gears, but I’m totally shocked that using the thumb lever on the right shifter gives a downshift, but using the thumb lever on the left shifter gives an upshift. And vice-versa for the triggers…using the trigger on the right shifter gives an upshift, but using the trigger on the left gives a downshift. It’s completely counter-intuitive to my brain and I can’t imagine the reason it would be this way.

First of all, is my bike assembled right? Is this the normal way all bikes are? If this is the “standard” setup, how did this convention ever arise in cycling? Is there some advantage to the controls being opposite that I’m not able to appreciate? And lastly, can I change the cable routing somehow so that the front derailleur both shift the same “direction”?

Answer 1

The reason why shifting is arranged this way:

• Shifting to a larger chainring at the front gives a higher gear ratio, shifting to a larger sprocket at the rear gives a lower gear ratio.

• Shifting to larger chainring/sprocket requires positive pulling force from the shifter whereas shifting to smaller chainring/sprocket can be done with derailleur spring tension. It's intuitive that getting the chain to climb up onto a larger chainring/sprocket will takes more force than letting it fall down.

• Its easier to get positive pulling force from the thumb shifter lever then the finger lever, there's more room for a longer lever and a longer lever throw. The thumb can travel on longer distance without the hand losing grip.

The exception is of course Shimano's Rapid Rise rear derailleur which use derailleur spring tension to shift to larger sprockets. THis obviously didn't work as well as 'normal' derailleurs as the type has disappeared.

Answer 2

This is the way most (99.999%) of bikes work. If you really want to change it - I advise against such a move, the only option would be hunt out a (fortunately) now defunct "Rapid Rise" or "Low Normal" rear derailleur.

I was unfortunate enough to install one on a MTB in the early 2000's. I still suffer a from of PTSD recalling the decade of screwed up gear shifting, lost seconds and embarrassing hill climb failures caused by learning, then unlearning "rapid rise".

Better would be go back to a 1x setup if you really find it a problem.

Answer 3

The old Shimano SIS levers were just indexed levers. The deraileurs were spring-loaded heding towars smaller chainwheels. Thumb pushing lever is much more effective than index finger pulling lever. Also note that index and middle fingers should be on the brake levers most of the time.

Other design is rolling drum (simillar to motorbikes accelerator/spark timing controllers). Here it is easier to pull the drum rotatin towards you than pushing it rotating away from you. Again the indices in front goes against the ones in rear.

In modern index mechanisms, no matter whether MTB or roadbike integrated, the thumb lever (the longer one on roadbike) demands higher force to overcome the spring and the index-finger (the shorter on roadbike) is the other.

Speculation below:
I think this direction has also one advantage that when both wires fail, the chain gets set in the lowest tension setup. And also to the easiest to access and service.