Originally Posted by
Winfried
Thanks for the idea. The dual speed derailleur I used first worked fine at the expense of the chain rubbing against the inboard lip on the biggest two-three cogs in the back. Maybe I should try again with a serious angle grinder to remove more.
I then tried a triple, which did solve the noise issue… but the derailleur had an even harder time reaching the outter ring to the point I often had to get off the bike to move the chain by hand :-/
Besides the extra weight, a 100km test ride with the Alfine 11 left me more tired than riding the 2*7 derailleur solution, hence my looking at alternatives. But I appreciate the total silence, the single shifter, the ability of changing gears even at a standstill, and the lower risk of hitting the rear derailleur — it happened a couple of times, speeds would no longer work correctly, and I had to pull it outwards to fix the problem.
OTHO, the gear hub + cassette means two shifters, a derailleur prone to be hit (20" wheel), and a lot of duplicates/close speeds (~ 14 unique/useful combinations out of 3*9) :-/
"I mounted a 50/34 double with hollow spindle and external bearings, almost as much range and a far superior crank and bearing system in many ways" : What would replacing the square taper BB bring? Less weight, better performance? Would you have a link handy?
The front derailleur I use is a Microshift 9 speed triple. Triple because I had originally planned for that, but glad I got it anyway with my 2X as the longer cage means no chain drag on small cog/chainring combos (though I try to avoid). That FD had an unusually wide and thick top lip bent inward, way overkill in stiffness, my guess is for harsh MTB applications. I ground off what lip interfered in the locale of the seat tube, but none of the vertical cage metal, and it is still plenty stiff. It is a road style FD, as band-clamp style FDs are NOT made in the huge ~40mm seat tube diameter. It is mounted with a road derailleur adaptor by Litepro, sold by a folding bike dealer. The spring force on this FD is huge, too much for grip-shift, and even with a trigger, I need to push straight on the lever with my right thumb, not try to swing my left thumb as that will cause injury. A Shimano FD would be lower spring force, but won't fit the FD adaptor; The Microshift has a cantilevered linkage, but the Shimano linkages are in double-shear, better design, but the linkage is just forward enough to prevent proper mounting on the adaptor.
2-piece hollow-spindle cranks (first seen on Shimano Hollowtech II) have the following advantages:
- lighter weight
- bearings being external, there are more balls and/or larger, so more durable
- bearings are closer to crank, so the spindle is more loaded in shear and less bending
- easy to axially preload bearings (no slack), and can adjust over time to maintain, this greatly improves bearing durability
- easy to remove crank with only allen wrench, not crank tool
- unlike square tapers, with choice of either dry and stuck on over time, or lubed with anti-seize and sometime coming loose. Left arm clamps securely around spline.
- backwardly compatible to fit BSA/English BB threading.
- 43.5mm chainline (for 2X), dead perfect for my 130mm OLD 7 speed.
- crank with integral spindle, chainrings, bearings, was $60 on amazon, great quality. I needed to buy special bearing wrench, $20-25 I think, but is a 4-way one to handle that many bearing spline patterns.
Only possible downside: Bearing seals are close to inside face of crank arms, so dirt in there might grind, versus square tapers where the seals are recessed. My bike is strictly road, but this might be a factor for serious off-road in mud.
Rear derailleur: GS (mid) length cage works for 50/34 x 11-30, and it has capacity to do 34 cog. But still sufficient ground clearance. I used Shimano Tourney with integral claw mount as my folder did not come with an FD adaptor, it used the Dahon compact style forward of the axle. This shifted much better, gave me the capacity I needed, reversed shifting from Dahon/RapidRise to normal, and was dirt cheap at $13. "Lighter than air, stronger than steel, cheaper than dirt."
The above gives me 21-85 gear inches, or just over 400%. Others on here have gotten the same range with 1X gearing with very wide cassette range, requiring only a compatible freehub body (not 7-speed), rear derailleur design for the wide cassette, and the cassette, assuming all are compatible with your frame rear O.L.D.