What I want to know is, has Brucey actually tried all these combos, or he is just very adept at trawling a gazillion obscure internet sites and collating the info and having the extraordinary ability to remember it all?
to much time spent in the shed fiddling about, I reckon.
I first ran 8s chain through a 9s mech about 20 years ago; RD-M750 I think, with shimano 8s HG chain. IIRC they use the same pulleys in 9s and 10s XT/Ultegra mechs, so, barring odd cambers on the side plates, that normally works OK too.
Re RD-M4000; I didn't bend it but one of those holds my personal record for 'the most mangled (modern) RD that I have made straight again'. In an ideal world, one simply buys new stuff when old stuff breaks; it's not difficult. But sod's law says that you don't always have that choice and
a) knowing what might work if push comes to shove,
b) knowing how to fix stuff that is quite knackered and
c) knowing how long that repair might last
are all quite useful things. Years ago my (practically new) pedals on my touring bike decided to clap out at a very low mileage; the bearings in both pedals had developed an alarming amount of free play very quickly. I think I was somewhere in Switzerland at the time and it was late on a Saturday when I discovered the problem. The chances of buying new pedals the following day were nil, and I was anyway quite a long way from a bike shop. I'd ridden hundreds of miles to be there; many mountains with inviting roads draped over them like spaghetti beckoned me, and I didn't want to miss a day's riding.... so as night fell, I rebuilt the pedals as best I could so that at least I could try and ride the following day. It looked very much like the cones hadn't been hardened properly, but the bearing surfaces looked as if they had worn in such a way as the load might be shared between several balls if the bearings were adjusted correctly. Lots of sparkly bits of metal came out. I wasn't optimistic but I cleaned everything, checked the balls, applied fresh grease and hoped for the best.
Well, to my surprise the pedals worked OK the following day, and the next. Many cols were ridden. I went past a bike shop the day after and I didn't bother to buy replacement pedals. In fact the pedals were still working about two thousand miles later and I think I sold the bike with them still attached, telling the new owner 'they wouldn't last for ever'. I was right; some swine pinched the bike mere weeks later.
Anyway I've usually got various comparable 'horrible experiments' underway; despite this it has been quite along time since I have been stopped by a conventional mechanical problem; I've had to walk home several times in the last eight years; once through lack of booting fabric and a particularly big hole in the tyre, and three times because the frameset broke. In all three cases the frame broke because it was badly made, and in two cases I should have spotted the crack but didn't. In the third case the cracks were hidden from view. In all three cases I became alarmed at the way the bike was feeling and I climbed off the bike before it failed catastrophically.
[edit; I also broke a rear axle in an IGH; it had done about 70000 miles.]
By the time I have figured everything out I shall be so old and decrepit I shan't be able to ride a bike any more... ho hum....
cheers
