MTB to Gravel/Commuter

Hi all,

Since I haven’t done much on my bikes outside of basic maintenance, I started my mechanical journey with a fork replacement ( Rebuilding MTB for commuting - Tech & Product - CT Community (cyclingtips.com)). That went quite well, so now it’s on to bigger goals.

The bike I want to convert to a gravel/commute-combination (see pic in the linked thread) is a roughly 25 year old hardtail MTB. The bikes geometry can be seen here: Bike Geometry Calculator (bikegeocalc.com)
My plan, after replacing the suspension fork with a smaller and much lighter stiff fork, is to replace the groupset (currently Shimano Deore XT 3x9) with a 1x groupset and switching to dropbars. To some this may sound like an hours work, to me that’s more like a gigantic project and I honestly don’t really know where to start. So much to consider … compatibility, tools needed, selection of parts, etc.

Now on to the questions. Well, first off - if you think this conversion is complete nonsense, please let me know. I always appreciate an honest opinion.

  1. I absolutely want to go with a 1x groupset. The Shimano GRX is pretty much impossible to obtain, so I figured I go with either the SRAM Apex or Rival. Any ideas what else could be useful? I saw Sensah on Aliexpress but lacking experience with it, I don’t really trust the cheap Chinese stuff.

  2. Lets stay with the groupset - how can I find out if my current freehub is compatible with the new groupset? Any ideas? Also, how about the rear derailleur hanger?

  3. Regarding the handlebar - the current flat bar is 520mm wide. I thought about a drop bar with 420mm and to compensate for the additional reach of the drop bars, I would switch the current 130mm stem to a very short one with 60mm (and 7 degrees). Do you think that makes sense? Anything else to consider here?

  4. In order to work with the STI levers, I have to switch to Mini-V brakes. I thought about the XLC BR-V04 due to their rather long 85mm legs. Any better ideas?

  5. Last one (for now), and possibly an embarrassing one. It looks like a pressfit BB, right? How do I know which one to choose for the new crank?

If you have any other ideas, suggestions or hints/tips, I’m immensely grateful for everything!

Thanks a lot!

Flo

Sounds like a fun project!

Your groupset choices will be constrained by both the freehub width and mechanical brakes. I’m not positive, but I think you could go up to 10 speed without issues with the freehub or derailleur hanger. I’ve heard that Sensah is decent, and Microshift is another option. If you stick with 9 speed, there are even more choices because mountain and road derailleurs use the same cable pull so you can use a mountain derailleur with road shifters.

Your bottom bracket is almost certainly a threaded BSA type. There is a tool that fits into the notched ring around the edge. Probably best to search for some videos on removal because they can be a bit tricky. The good news is there will be plenty of options for new ones. You will need to match the width (68 or 73 mm) and crank spindle type.

100% OK with what Jann wrote.

To know if you should go for a road / gravel or MTB crankset, just measure the width of the frame at the BB (68 → rodad / gravel, 73 → MTB).

Thanks for the info.

@Jann_Mayer Please allow me to follow up here. I’m utterly helpless selecting components that are compatible.
Unfortunately, the Shimano website isn’t really helpful when it comes to compatibility. So, after quite some reading, here is what I have put together as a potential Shimano setup:

Rear derailleur: Alivio 9-speed (RD-M3100-SGS)
Cassette: Alivio 9-speed 11-34 (CS-HG400-9)
Crankset: GRX RX600 1x11 in 175mm (FC-RX600-1)
Bottombracket: Tiagra threaded (BB-RS500)
Shifters: Sora R3000 2x9 (ST-R3000)
Chain: 9-speed chain (CN-HG53)

First - and obvious - question: can anyone say if that might be compatible?
Selection process was: MTB rear derailleur (and cassette) work ok with road shifters. GRX crankset is 1x and therefore should be ok.
The left shifter will have no shifting cable, just the one for braking.

I’ll switch the current V-brakes to mini-v’s so they work with the road bike shifters/levers.

Are there any better ideas regarding the combination?
I tried a SRAM-setup, but … well … I failed :frowning:

Thanks again for your help!

A 10-speed Sram setup will let you mix and match any component (as long as the rear derailleur can handle the cassette).

For any 1x build where the rear derailleur has no clutch for chain tension, I guess you’ll need to address chain retention.

I think your drivetrain is mostly compatible, although I don’t know how well the chain will start on the 11 speed crankset since the chainring is narrower. 1x systems usually do need something to help hold the chain on the ring when riding on rougher surfaces. Since the derailleur has no clutch, a narrow-wide chainring or even a chain catcher would be a good idea.

There’s no real need to stick to Shimano for the cranks, so there may be cheaper options from FSA or Praxis or others. The cranks themselves are not so critical since you can usually use any chainring with the same bolt pattern or direct mount interface. This would also give you more flexibility with you chainring size, although I haven’t looked for 9 speed narrow-wide rings before. (If you don’t mind a wait, there are lots of cheap chainrings on AliExpress.)

I have no firsthand experience with Microshift, but their SBR-490 shifters (R9 series) are made for 1x9, so the left lever has no shift mechanism. It’s also likely to be cheaper.

Unfortunately I’m away from my computer for a while and can’t give much better advice about the cranks.

I should have mentioned that the bottom bracket width will determine which cranks will work. Measure the width of the frame at the bottom bracket - it should be either 68 or 73 mm. The cranks will need to be designed for that width.

You guys are awesome! You reply faster than I type my posts :laughing:

I’ll do some more research, especially regarding the narrow-wide chainring and see where it takes me. I might come back with one or two more questions in the next few days I’m afraid :see_no_evil:

Thanks again and have a nice evening!

1 Like

I have just spent a lot of time trying to figure out a workable combo of narrow-wide chainring, cranks, spindle and BB. And haven’t gotten anywhere :sob: :sob: :sob: :sob:

I’d be very grateful if anyone could recommend a combination that fulfills the following criteria:

  • narrow-wide chainring (for 1x setup with 9-speed cassette)
  • 175mm cranks
  • for threaded BSA bottombracket with 68mm

I really like the RaceFace chainrings, but can’t figure out how to combine them with (cheap) cranks. However, by now I’d take pretty much anything that fulfills the above mentioned criteria and doesn’t cost a kings ransom.

Do you think something cheap like this would work?
RACEWORK MTB Mountain Bike Alloy 170 175MM Crank 32T 34T 36T 38T Direct Mount Narrow Chainring 68 73 BSA BB Bicycle Crank Set|Bicycle Crank & Chainwheel| - AliExpress

Thanks!

I think that would work, as long as the 38 tooth ring is big enough. However, the ring interface looks the same as the SRAM direct mount interface, so rings designed for SRAM cranks may work.

I’ve seen a few people use Racework cranks on build but haven’t heard any feedback either way.

Please let us know how this works out. I really hope I haven’t given any bad advice!

If you knew how immensely grateful I am for your input (or put differently - how hopelessly lost I’d be without it).

I’ll start ordering all the bits and pieces. That will take a while, especially the stuff from aliexpress. Once all is in, I’ll start working on the bike. Lacking an indoor workplace, I might have to put it off until early spring (that’s usually late Feb, early March here). I wonder if I can possibly be that patient though … highly doubtful :smiley:

I’ll definitely keep you posted :+1:

@Jann_Mayer Please allow me one last question that came up while ordering the components.

I was going to go with the Shimano Alivio MTB rear derailleur. That’s a 9-speed with a long cage. Since I’m gonna go 1x with a rather small cassette (11x32 or 11x34), I figured I could go short cage and get something like the 9-speed road derailleur Sora RD-R3000-SS.

Does that make sense? What do you think?

@floklinge I think the Sora short cage would work, although 11-32 is the largest cassette it is rated for. The Alivio can take up to 11-36 so you’d have the option for a wider range cassette in the future if you wanted. I’d go that route, but I live in a hilly area and like having a wide range. If you know 11-32 is good, the Alivio or either short or medium cage Sora should work equally well.

Thank you!

All parts have been ordered. Some deviations from what was previously planned, but we’ll see if it all works together :laughing:

I’ll give an update when the rebuild is underway/done/failed.