Kommisar89

I was at the LBS today and notice they had a 40t 110bcd chainring hanging on the wall so I said "What the heck, why not?" and took it home. Now in theory this should not be a good idea. My Panasonic was equipped with half-step + granny gearing - 50-46-26. And I absolutely hated it. Any hill that was too steep for the big ring was too steep for the 46t ring too so effectively I had one big ring and one tiny ring and nothing in between. But according to conventional wisdom, my Shimano half-step front derailleur should not shift well with my current 50-40-26 combination. Well, as far as I can tell, it shifts just fine. The only surprise was that I needed to adjust the limit screws on the FD. I didn't expect that since I was changing the middle ring but while I could shift up 26-40-50 just fine, the downshift from the 40 to 26 would not go. I had to both loosen the cable and back off the limit screw to get the deraileur to drop low enough to make the shift cleanly but it does and now there is not problem. If there is a difference, it's that before you could make the shift to the middle ring with minimal trimming: move the lever up or down about half way, the chain moves to the middle ring, done. Now, regradless of which direction you are shifting you have to overshift just a bit and bring it back a little.

I don't consider that to be bad shifting, especially now that I can use the middle ring. Is that what they meant back in the day when they said shifting was bad for triples with cross-over + granny gearing? Shimano even made a cross-over version of the FD but I don't think I'm going to run out looking for one anytime soon.

supton

I really like the 52/40 rings on my bike--one FD shift is worth two in the back. Makes for a wider range of gearing, and possible to use one ring for one type of riding, the other for different riding--uphill and cruising on the 40, downhill and downhill-followed-by-flat in the 52. I've wondered what it'd be like to have the FD worth two RD shifts--triple step?--but I think the large difference in chainrings would make for really hard shifting.

I consider "bad" shifting to be what I get on my RD when I'm chugging up a hill, and absolutely cannot get the gear right as I'm downshifting. That is either due to autoshifting or the RD being noodle-limp--when I'm not under power it shifts ok.

John E

If you look at the trajectory of a front derailleur cage, a more even progression, such as your 50-40-26, should work well. However, mathematically, it is tough to beat a well-planned half-step or half-step-plus-granny.

My compromise is the 1.5-step-plus-granny, which is not far from what you are doing. I run
48-40-28 or 48-40-24 / 13-15-17-19-22-24-26 on the Schwinn, and
46-38-24 / 12-13-15-17-19-21-23-25 on my wife's Ross. An 8-tooth drop in front provides about 1.5 times the ratio step of a 2-tooth progression in back.

I run 50-42 / 14-16-18-20-23-26 on the Bianchi, and if I ever went to a triple for some wall-climbing gears, it would probably be something like 50-42-30 / 14-16-18-20-23-26.

Kommisar89

I guess the problem is I grew up in New Orleans where I hardly shifted on the absolutely flat terrain there so I never really learned shift patterns and now I live in Colorado where half-step, granny or not, is practically useless. I never learned to double shift so it is not an ingrained habit with me. I've always used cross-over gearing. So it's granny gear for big hills, middle ring for medium hills, big ring for flats and downhills. I'm just glad this combination works well. I suspect a new triple front derailleur would work even better.

Skip Magnuson

Bad shifting is when the chain ends up in the spokes.

el twe

No, that's a bad derailleur adjustment.

Kommisar89

+1

I've only experienced two types of what I call bad shifting. With the old plunger style FD like the Simplex Prestige or Campag Valentino I've had the chain skip a few beats before making the upshift to the big ring but that was a fairly minor annoyance. The Nuovo Record FD shifts flawlessly with a 52-40 setup. With the old style square tooth freewheel cogs (pretty much anything European from the mid 70's or earlier) I've had it skate along the top of the cog and "freewheel" until it completes the shift. That is VERY annoying. Didn't seem to matter which derailleur, it's happened with the Simplex Prestige, and Campag Valentino and Nuovo Record RD's. Swapping the freewheel to a Shimano "bent tooth" or whatever you call it design solves that problem.

I've had no issues like that with the Panasonic. In fact it's been much better than even the Campag Veloce Triple drive train on my Bianchi when I pushed it with a 52-42-26 and custom 13-30 cassette setup. That was a very touchy combination and would occasionally drop the chain on the shift to the little ring and made the little ring/little cogs unusable due to chain slack. Fortunately I got strong enough that I didn't need the unusual triple setup and eventually went to a double crank and standard cassette.

MKahrl

I think the problem on alpine plus granny on old triples was when the middle ring "hid" during the shift from granny to middle. As the derailleur pushed the chain over at an angle (the very back and bottom part of the derailleur cage is in contact with the chain at this point) the chain would encounter the teeth of the large chainwheel before it encountered the middle chainring. This was made even worse (more likely) if you were in a small cog in the back.