Hopefully this is the right place for this kind of post. I’m embarking on my first bike build and need a helpful nudge from some seasoned wrenchers. I just do basic maintenance and upgrades on my other bikes, but I’m fairly handy as a tradesman and part of the desire to build my own is not only to save money but also to learn.
Long story short: I got a great deal on this used custom carbon gravel frame with a BB-RS500 bracket, dura ace cranks, ritchey drop bar cockpit, and brand new set of DT swiss wheels. The rear wheel came with a SRAM Rival CS-XG-1250-D1 10-36t 12sp cassette and XDR driver and am trying to figure out a decent drivetrain that would work with these. My aim is to ride equal parts road and gravel, and want to keep this build affordable but worth the time and effort.
Short story longer: I would prefer a mechanical groupset for the price tag and personal preference, and the best bang for the buck options I’m seeing appear to be SRAM’s other Apex offerings: Eagle HRD 1×12 11-50t and the XPLR HRD 1×12 11-44t. Would either of these work with an XDR driver and/or my current cassette (it appears these may only be HG11 compatible)? If not, is it worth exploring changing out the driver to an HG11, or might swapping out the cassette for another XG model work with either of these Apex component lines? Open to suggestions, any guidance appreciated. TIA
by Xachtly
1 Comment
If you’re looking for 1x drivetrains, given that you already have a XDR driver, any reason not to get a cassette with a 10t small cog? With that XDR driver you gain the luxury of using the 10t options. They can be a bit more expensive than the offerings from Sram at the lower end of the range (these tend to have 11t instead of 10t), but can also be found secondhand pretty readily. For example, this [https://bikecloset.com/product/sram-gx-eagle-xg-1275-12sp-cassette-10-50t/](https://bikecloset.com/product/sram-gx-eagle-xg-1275-12sp-cassette-10-50t/) should suit your needs quite well, is a great price and will give you a mullet set up with plenty of range. From there, you can do anything from a 40t chainring and larger to give you a good amount of range. Won’t be quite equivalent to a 2x, but should still be adequate for your average road riding.
Rear derailleur will have to be in the “Eagle” family in order to have compatibility with the 50 and 52t large cog cassette options. If you were to get a smaller cassette (40, 42, 44t), then you’re looking at working in the “XPLR” family. Anything 36t and below falls in their road range and is really best suited to a 2x set-up. I probably wouldn’t do anything lower than the XPLR offerings (ie get a large cog that’s 42t or larger) for gravel 1x use as you’re likely to have insufficient range of gears and it just isn’t as much fun grinding your way up loose climbs.
The other question to answer will be the compatibility of your current crank with the size chainring you’re looking for. You’ll have to identify the Bolt Circle Diameter and the bolt hole pattern to see if you can find anything to suit your needs. I imagine that you’d be able to find some aftermarket options from a company like WolfTooth, but I’m just not familiar with those older 5 arm-spider Dura Ace specifications.
Hope that helps a bit. You may have already seen this as well, but here’s the sram road compatibility map: [https://www.sram.com/globalassets/document-hierarchy/compatibility-map/road/road-compatibility-map-2023.pdf](https://www.sram.com/globalassets/document-hierarchy/compatibility-map/road/road-compatibility-map-2023.pdf)