Recent rides have included sustained not-small gradients, sometimes on very nasty loose rocky unpaved surfaces.
I got tired of having to muscle up the steepest spots in a
huge gear like 24-28, so I decided to upgrade my cheapo allroad drivetrain to the
ultimate cheapo allroad drivetrain.
Previous cassette:
11-13-15-18-21-24-28
New cassette:
11-13-15-18-21-24-28-
32 Chainrings remain the same as before, 48-38-24.
So I get some bonus low-end without giving anything up.
Also, since the middle ring has access to a lower gear than before, I don't need to bail to the tiny ring as often. That's nice, because 38->24 is a dramatic shift!
The first problem I ran into was that the Alivio M410 derailleur had insufficient wrap. Easy solution: a newer Alivio T4000 derailleur is rated for 45 teeth of wrap, exactly what my drivetrain uses. That new pulley cage is
huge! The first problem that I almost had, but actually made things easier, was chain length. A new 116-link chain was perfectly sized right out of the box!
The second problem that I had was was chain clearance. The large cog is farther inboard than before. In the small-big, the chain was interfering with both the tire and fender.
Solution: push the chainline farther outboard! (And since the NDS arm is farther outboard than it needs to be, I might as well bring it inboard at the same time.)
The old BB has a 118mm spindle. The new BB has a 115mm spindle...
...plus a huge drive-side spacer!
I've pushed the DS outboard by 2.5mm while brinding the NDS inboard by 5.5mm. Seems to get the job done.
The remaining problem: I haven't quite dialed in the FD adjustment. The shifting is very crisp, but the chain is intermittently being thrown off the inside on downshifts to the small ring, and neither pedaling form nor feathering the shifter seem to offer a consistent solution. Since the chain isn't jamming on the bottom run when this happens, I might just see if a simple chain keeper makes the problem disappear.
Bike: