I've been doing it occasionally for years and never had any trouble. I do it changing up and down, on road and off, trail bikes and road bikes. I don't know the details of what's going on in the gearbox, I just tried it when I was told it worked and that that it didn't cause a problem - and so far so good.
The views expressed above may not match yours - But that's the reason my Dad went to war - wasn't it?
Life's journey is not to arrive at the grave safely in a well preserved body, .... but rather to skid in sideways, totally worn out,... shouting "man, what a ride"!!!
Bookmarks