I have considered switching to a triple crankset on a few occasions on my Bob Jackson, it certainly wouldn’t be out of place on a touring frame, but I rarely “run out” of gears and on balance there have always seemed to be a lot of disadvantages for some infrequent benefits. I run a Sugino Alpina compact crankset (48/34) with a 105 12-27 cassette and although I rarely cross over completely, it will happily run through all the gears in both chainrings which is really convenient for lazy / rapid changes. With a 48 big ring in fact I rarely use the smaller ring. I don’t race or go full pelt on this bike so there would be no advantage in having the 53 ring of a triple it really is just for the odd loaded, tired, up hill.
Enter the Ultegra 12-30 cassette. I fitted this last night, it honestly took no more than a few minutes as it turned out to need no adjustment of my 105 short cage rear derailleur, I was fully expecting to have to do a minor tweak of the b-screw and had a new chain on standby as I thought I may be a link short.
This gives me a range on the big ring (in gear inches) of 108” to 43.2”, previously 48” - and on the small ring from 76.5 to 30.6”, previously 34”.
My obvious concern was the gap between the gears but in fact the transitions seem very sensible and well spaced, albeit that I will rarely use the 30, nothing wrong with 9-speed though!
On my Condor Acciaio I have an 11-28, the 24-28 jump feels pretty big, to be honest a 27 big sprocket would be a better match, but there is no such thing as an 11-27, only a 12-27 or 11-25 and I would rather not give up the 11 as a highest sprocket or the 27 as a large sprocket, so the 11-28 seems the best compromise.
In conclusion, for me this is a much better solution than fitting a triple, it gives me a 30.6” lowest gear, virtually identical to what I would have had with a triple and my original 12-27 cassette. Perhaps it’s also a viable and cheaper fix for those on a road bike with a standard 53/39 crankset needing lower gearing, giving a 34” lowest gear, where previously a compact was needed to get this low.
Shimano 10 speed sprocket configurations:
11-12-13-14-15-17-19-21-24-28 on Condor Acciaio
12-13-14-15-17-19-21-24-27-30 now on Bob Jackson World Tour
12-13-14-15-16-17-19-21-24-27 previously on BJWT