gauvins

As indicated in previous posts, I've tweaked my trekking drivetrain.

Stock trekking Shimano (T780) comes as 48-36-26 x 11-34.

I've first swapped the 26T granny for a 22T, and the cassette for an 11-36.

I've also purchased a Miche Primato 15-24 and used its first 4 cogs to replace the free cogs of the XT cassette, yielding a frankenCassette 15-16-17-18-19+21+23-26+30+34 (+ means on a spider). Works so far, but not ridden significantly so not clear if this tweak will survive through spring.

Frankly, the nominal trekking gearing is not bad at all, except, maybe, the 11T cog that is almost never used in conjunction with the 48 chainring, and rarely with the mid ring, largely because shifting from 13 to 11 is too much of a gap.

I wanted to get lower gears in order to be able to climb steeper hills under load (22x36 is almost dangerously low as it is easy to push so hard as to get the front wheel to lift from the ground). I also wanted to try a system offering small increments (15-16-17-18-19) that make it easier to keep a steady cadence. The price to pay is the need for more shifting on chainring change and possible deterioration of shifting smoothness between the XT 19 and Miche 17.

IK_biker

And the purpose of starting this thread is?....

escii_35

The one thing you need to worry about with running a 15T first gear is the dropout to chain-stay interface. The chain may get stuck there during a downshift.

I just wish more manufacturers offered cassettes which started at 13T. Give me density where I can use it.

Tourist in MSN

Your lowest gear is pretty close to mine on my expedition bike. I picked that gear ratio because that would give me a cadence of 72 at 3.5 mph. I felt that 3.5 mph was the slowest that I could maintain directional and vertical stability without undue steering corrections. And my slowest cadence that feels quite smooth is 72, if it drops below that my pedaling does not feel very smooth.

gauvins

You are right. Shimano warns against using a junior Ultegra 6600 (ex: 16-27) with a triple crank precisely for this reason.

My rig is built around a LHT frame. No chainstay issue despite a triple.

gauvins

Yes, I remember reading your thoughts on gearing. Well written. I'd reached similar conclusion based on the fact that I wanted gearing that would bring me closer to walking speed. 15.7 gear inch is probably the smallest feasible solution.

Not sure yet if it is definitive. Might prove to disrupt shifting progression (the gap between mid/small chainrings is quite large.)

I'll eventually share my impressions. For now just wanted to share the fact that Shimano's trekking group appears to be quite tolerant. I've had no immediate problem despite larger cogs and smaller granny, that are outside of the recommended range.