Bicycles Asked on August 20, 2021
This may be a stupid and uncommon (definitely seems so) question. Also forgive me for potential etiquette violations, as this is my first one on bike stackexchange.
I’m thinking about buying a gravel bike (nukeproof digger comp 2020) which has the Shimano GRX 1×11 drivetrain. Having almost no experience with gravel bikes, I’m just trying to understand, whether it would at all be possible in the future to "upgrade" to 2×11 – should the need arise.
So consider this a thought experiment: what would be necessary for such a conversion and what are the potential problems/showstoppers?
Thanks!
p.s.
The rather scarce relevant posts here (see below) did not help me definitively. Also there are might be some GRX specifics
I’ve also read several articles on extending 1×11 range with aftermarket cassettes and hardware, such as this excellent one on bikepacking.com and understand that something like that might very well be the (significantly easier if more limited) solution too
It depends. For most gravel bikes it will be an easy, yet expensive, swap. A couple of gravel bikes frames are built in a way that makes shipping a front derailleur as good as impossible. There may not be enough room for the chain stays to clear a second chain ring. What is more, some frames lack mounting positions and the shape or material of the seat tube does not allow clamping. A minor obstacle might be cable routing.
Many gravel bikes come in 1x and 2x configurations. Only the group is different while the frame is identical. Migrating on these bikes from 1x to 2x is easy to do. The costs involved are substantial though. You will need to replace crank-set, brifters, rear derailleur, chain, bar tape.
Unless you use SRAM's wireless group you also need to rout a cable. As before, gravel bikes that come in a 2x configuration make this easy. Bear in mind though, for internal cable routing you might have to remove the bottom bracket. Cable routing can be substantial and frustrating work, and may be expensive in a shop.
With so many components to replace, a good way to estimate component costs is to look at the price of a group set. It is typically at about 1/3 to 1/2 of the complete bike's price. Together with small parts and finishing kit you can expect the cost of modification to exceed the value of the bike after a year of riding.
Correct answer by gschenk on August 20, 2021
gshenk's post is excellent general answer, here's the specific answer for the setup on the Digger Comp.
The Digger comes with an RX-600 40t crank, RD-RX812 derailleur and CS-M7000 11-42 cassette. The RD-812 derailleur is compatible with wide-range mountain bike 11 speed cassettes (which have different spacing that 11 speed road cassettes). It's not designed to be used with a double crank.
This of course means that converting the bike to 2x would involve replacing the entire drivetrain.
You can compare the RX-810 2x and RX-812 1x components and see which other components they are intended to be used with on this Shimano component line-up page. Note that the 812 setup with a 42 tooth crank gives you 0.9 - 3.6 ratio spread and the 2x 810 with a 11-34 cassette gives 0.9 - 4.3, with smaller gaps between ratios. The 1x drivetrain sacrifices gear ratios for simplicity and chain retention and control.
Think what you want to do with a gravel bike. If you want to ride rougher off-road trials exclusively a 1x bike may be better. If you want more flexibility and to use the bike on road as well as off a 2x bike would be better.
Answered by Argenti Apparatus on August 20, 2021
I can't speak to GRX specifically, but one of the Old Saws of cycling is "Buy the bike you want" which means to avoid buying a bike with the immediate intention of upgrading/replacing parts.
Generally speaking, a new bike will work well together - by swapping things about, that new-bike feel may diminish.
Unless your LBS is really nice and credits you for take-off parts, the cost penalty of buying the bike with bits you don't want and additionally buying more parts at retail will soon add up. If you intend to swap the parts yourself then this may make any warranty claims later problematic.
However all this goes out the window if you're talking about a used bike, where there are no warranties and parts come pre-bedded-in (or worn out)
Upshot, Buy the bike you want to ride, in the spec you want.
Answered by Criggie on August 20, 2021
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