>It is a *logical* idea.
Dear Benz, We could have had this "logical" action with either a reverse-acting front derailleur (offered by Suntour and others for a spell) and the "Rapid Rise" derailleurs, among many others--the first modern derailleurs used a reverse rear action, and it comes back from time to time. We adjusted to the way we do it after initial designs that work "logically." I speculate we end up with our current arrangement for two reasons. One is ergonomic, and one is functional. The ergonomic argument makes the most sense to me. First, when one double-shifts with a standard setup, (i.e. going from small to big ring up front, simultaneously shifting to a bigger cog in back), both levers move in the same direction, facilitating an easy one-handed shift with downtube levers. It is the same muscle movement for Ergo levers i.e. actuate both inner levers or both thumb buttons, and it is the same distance of travel to make the shift work right if you're using "racing" gears; similarly for barcons. It requires much more dexterity to do an accurate simultaneous double shift with friction levers (it is easier with indexing) and one reverse-pull derailleur in the mix, and it is two different movements with barcons or the various integrated lever systems. Consequently, a single reverse-pull derailleur is a huge hassle when operating a half-step, for example, when (sequentially anyway) every other shift is a double, or if you're between ranges on a compact double. Now, this could have been done with either the standard setup, or with both lever pulls reversed, so why set up with high-normal in the rear and low-normal up front? When a rear derailleur cable fails (or is not installed), the derailleur moves away from the spokes in a standard setup. This eases installation and limits/eliminates the possibility of a derailleur getting mashed into the freewheel or spokes unexpectedly. Also, in very early designs, derailleurs had no limit stops, and a failed cable threw the derailleur into the spokes.... The Cyclo, with no return spring, was a huge step up--at the expense of double-cable design. The front derailleur also gets muscular support (vs a spring) to force the chain up onto the big ring, and you get direct manual feedback on when the chain has caught, which is when you can safely apply power to the cranks again. Cheers, Will William M. deRosset Fort Collins, CO On Monday, December 28, 2015 at 11:49:14 PM UTC-7, Benz, Sunnyvale, CA wrote: > > It is a *logical* idea. > > Imagine if we didn't have the legacy baggage of pulling cable to downshift > in the back. Wouldn't it make more sense if both front and rear derailleurs > did the same (upshift or downshift) if a particular action was actuated > (such as pull or release cable)? With rapid-rise (or Low normal), Shimano > was just harmonizing front and rear derailleur actions so pulling cable > (with DT, thumbs, barends & STI) will all result in upshifts. Sounds pretty > logical to me and it should be easier to teach newbies too. > > I also seem to recall that one of the technical reasons for rapid-rise was > to improve rear shifting. Apparently, the downshift-facilitating ramps on > the HG cassettes work better when the chain is gently prodded by a spring, > rather than getting ham-fisted with an overly eager rider. > > In any case, it's not a particularly hard skill to switch to. No shifts > are truly critical for non-pros, so a mis-shift here or there isn't bad. > One can always harmonize all Shimano-equipped bikes with rapid-rise rear > derailleurs! :) > > Anyone remember the reverse shifting Sachs *front* derailleur? > > > On Monday, December 28, 2015 at 11:28:37 AM UTC-8, Garth wrote: >> >> >> Rapid Rise was doomed before it even started ! If it was such a great >> idea then why didn't they make all shifting that way, mtb and road ? ... >> _______ ..... exactly . Saying it was good for some and not the other >> right there doomed it. A solution to problem that didn't exist. >> > -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at https://groups.google.com/group/rbw-owners-bunch. For more options, visit https://groups.google.com/d/optout.
