zacster

One thing I've been noticing as I ride various upright bikes is that the thumb shifting varies a lot. Some, like my 10sp Deore shifter/XT derailleur dyna-sys combo shift really easily. Others, like the old 7 speed LX it replaced, required me to push hard with my thumb.

I bought my daughter an old Trek to serve as a campus bike, and it had some very low end 7 speed retro-shifting Shimano gearing on it, but this shifts really easily. I also have an old DX equipped bike that needs a full press to get it to go.

So what determines the effort that it will take? Is it the shifter having better leverage/mechanical advantage, or are the springs softer in the rear, or a combination of both? Or do I need to get new cables on the bike that doesn't shift well? It never did, it was the one thing I never liked about it when I bought it as a new leftover in 1995.

And one other observation, front shifting is always the same, even on a road bike. It is always a bit clunky.

Matt Gaunt

New cables and well-maintained pivot points on your derailleurs will make the most noticeable difference. Of course, there's a reason that Shimano, SRAM and Campy have ranges of components and the more you spend, the more pleasant the shifting experience. However, the fact remains that Dura-Ace or Super Record with bad cables and ill-maintained pivot points will perform far worse than a well maintained Sora system.

That said, I had a seven speed Altus set-up on a bike when I was younger and the shifters eventually gummed up and then died. On their way to their untimely death, they were nigh on impossible to shift, so don't rule out shifter internals in your investigation.

You say that it never shifted well from new so I would also check that the cable housing is long enough to allow the cable to move freely (particularly at the rear derailleur) and that there is little resistance where the cable runs under the bottom bracket shell to the front derailleur (I'm assuming it's a bottom-pull design).

If your front shifting is clunky, something isn't right.

FBinNY 

Over the years manufacturers have lightened the action of both derailleurs and brakes by using weaker return springs. This was made possible by lower able friction, with the advent of lined housings and die drawn inner wires. Weaker return springs in turn lowered cable tension, which lowered friction so everything is lighter action.

OTOH, there's a drawback to all this in that the return action is less positive, and the whole system is more sensitive to any increase in cable friction form dirt or wear. Some years back Shimano went a bit too far in the weak spring direction and spring boosters for mtn bike RDs became a popular item for a while. These days, folks seem to have dialed in the minimum force needed for return springs, and modern brakes and derailleurs seem to work OK with action much lighter tan decades ago.

However there can still be vatiation bike to bike based on variation in cable routing and friction.

Matt Gaunt

Yes. Remember the Sram Bass Worm?!