Groupset Overhaul from 2×9 SORA

media for attention: a low-end road groupset @ 5300m of altitude

Howdy.

After about 6000km and a bunch of crashes on the 2×9 Sora groupset I have on my alloy Silex, the chainrings are bent and worn down to nubs, the cassette doesn't offer meaningful gravel functionality and I'm definitely overdue for an overhaul. I don't think I want to upgrade the bike including its alloy frame because I like that serious crashes don't cost me the frame and I can't afford titanium.

What I have:

* 2×9 (48-32/11-34) with sora shifters and cable disc brakes, HG Spline M on a 142x12mm width rear hub.

What I would ideally upgrade to:

* 1×12 (42/10-51) with Wheeltop GeX, and I'm indifferent on upgrading to hydraulic brakes (field repair on cable brakes is easier, and I don't mind tuning them every few weeks)

My reasoning:

1. Single chainring: I like the simplicity and its the gold standard in gravel bikes. Clearly I haven't tried it myself but I like the simplicity and I like the resilience (less stuff to brake / tune). And 42T instead of 40 or 38 because going fast on road descents is fun 🙂

2. 12s electronic: Tuning the gears is a pain in the ass and much more so with more speeds. Dialling it all in with an app (and being able to do that while in motion!) would be brilliant. I have read in a few places that Wheeltop has the better app and RD over LTwoo.

3. Chinese brands: they may not be as good as the western oligarchy but that's alright. Still a massive upgrade over a western road groupset on a gravel bike. Also, once everything is set up and I'll need parts to maintain it, it'll be easier and cheaper to find these parts by my usual avenues (Ali, banggood etc)

A few things I haven't quite figured out yet and don't seem to be able to find clear answers for:

1. The spline under my cassette would probably need to be changed. Does that necessitate replacing the hub? Is my 142x12mm common and generally compatible with the parts I will need?

2. Aside from resistance to wear, are there any meaningful performance differences between a full GRX groupset vs. a random Ali-special cassette and chainring?

3. Is there much to be said for changing the bottom bracket? Any compatibility issues? I suppose friction here is the same ascending 5kph on a brutal hill as 50kph descending it if my cadence is the same, so am I right in considering a ceramic bottom bracket as a worthwhile upgrade? If there's any value in this thinking then I suppose friction in the bottom bracket and derailleur rollers should be as important to gravel riders as aero is to road riders.

4. Where I'm seeing electronic shifter upgrades on Ali, they're offered either with hydraulic calipers or "rim brake" I suppose that's Ali-speak for cable, but that's not entirely clear.

5. Even though the Wheeltop GeX is officially compatible with a 11-46 cassette range, I've read a few reports here and on Chinertown that people are getting it to work with 9- or 10- high gears. How can that be? Are people putting up with poorer shifting, or has Wheeltop just been a bit conservative in their claims?

6. Hydraulic v Cable braking. Why is hydraulic so broadly preferred? I would guess that people would like to avoid spending 15min tuning/realigning them every few weeks, but surely there's more to it?

Thanks for reading / Apologies for the essay / May the gravel be good to you