Not to dissuade any thoughts of "varidrives/cvts/separate gear-driven shiftable transmissions" as everything has advantages & disadvantages, but the pawl/freewheel systems are actually
really easy to maintain & service... provided ya don't drop any parts under the workbench lol - additionally most of our powertrains rely on some sort of one way freewheel somewhere. I've logged almost five
thousand miles in a single summer with my Rollfast & the freewheel in the shiftkit didn't give me the slightest problem. I've heard yer not "supposed" to use grease in them as the pawls may stick, but even before I installed it I repacked it with a quality marine grade bearing grease... and I've not had to do anything to it since. Another advantage of the jackshaft setup is ya don't hafta sweat the "sprocket bolted to the spokes" problem ofc.
I'm not sayin' shiftkits don't have their issues, just that the freewheel isn't one of 'em heh. My biggest problems were chain maintenance, side plate flex & a bit of a "pulsing" symptom. The chain issues annoyed me greatly at first as there's no easy tensioning method, then it occurred to me the miles I was racking up - that it wasn't so much undue chain wear as just the maintenance chains require. I jus' switched to the highest quality chain I could find *shrug* The side plate flex
is a problem with the older designs (three piece) and the cloned copies of the same. The copies are of the first edition SBP shiftkit, the 2nd edition was better in that there's a reinforcement plate on the engine drive side, but there's still some flex evident. SBP has developed the 3rd edition which is unitized & the sides are not as long, while I've not run one - a buddy has one and I think they've resolved that issue w/it.
The "pulsing" problem gave me fits however - there was "something" somewhere that was out-of-round causing a sort of lurching under maximum load. After going through the entire shiftkit setup
and engine looking for bent shafts & misstamped sprockets - it turns out that it's simply the square tapered shaft on the bottom bracket, where the pedal crank presses on. After replacing both the bearing cartridge and the pedal crank yet still having the problem, I took off the pedal arms and rotated them ninety digress to the next flat and that reduced the symptom a lot.
Interestingly, many don't seem to have this problem... but as I've replaced parts and it's still present just lessened, I've decided it's "tolerable" and perhaps just part of my bikes "personality" heh. It's nearly impossible to get the pedal crank perfectly true on a square shaft and that's the root cause, I could tear it down and experiment with shims etc. - but I've decided not to bother as it's now hardly noticeable, most likely is that my first pedal arm was a lil miscast.
Again tho - nothin' wrong with experimenting with other options, I jus' wanted to give a lil feedback regarding the shiftkits as I think them elegant in their simplicity