MTB to gravel bike conversion

Finally, I decided to write about my strange experiment – convert MTB bike to gravel. I rode MTB and liked that few years ago, but after a crash during one of the competitions, I completely lost my enthusiasm to that kind of bikes. I tried MTBs few times during these years, but always said “no, it is no it”. Last year (2019) I bought a very nice 27.5” MTB bike from second hand. Rode it a few times and again said no, but… that time was different. I liked that bike very much and decided, it can be excellent git for my girlfriend. She didn’t have bike, and we looked for something for some time. It was the beginning of that conversion history.

Base bike was Giant Advanced XTC 27.5” from probably 2016 – I’m not sure, but it was in very good / excellent condition. Equipped in light, carbon frame, Rock Shox Reba suspension fork, full Shimano Deore XT 2x10s (38/22T – 11-36T) drivetrain and also Deore XT brakes: excellent not only for daily riding, but for any competitions. It was real “fight machine”, also, with nice weight. The only potential downside was the original wheelset. Giant wheels are very solid, but not lightweight. Also, 27.5” is not the best option for XC racing now. Fortunately, geometry was modern:

Giant XTC Advanced 27.5" - Original
Giant XTC Advanced 27.5″ – Original

First changes: rigid fork, gravel tires

When I decided to make a gift from that bike, I have to change some things. First, was to cute seat post, because my girlfriend is shorter than me. I knew, she will not ride any high-demanding terrain, so I decided to replace Reba by rigid, carbon fork: it was a good choice, because geometry wasn’t changed, but the bike was more than 1 kg lighter than before and accelerate much faster. Next change was tires: to use WTB ByWays 650x47c: very good gravel tires, with slick center. After these changes, the bike was lighter and so fast. I had to also use a short stem, it looked some strange, but worked as expected. In the meantime, I changed 2x10s to 1x10s by removing front derailleur, front shifter and use 32T narrow wide chainring. Everything works perfectly without any additional changes.

Giant XTC - After first changes
Giant XTC – After first changes

Swap wheelset to 29″

My girlfriend rode this bike few times this year (2020) and it was good… But still a bit too big for her. Then we decided to buy a new, road bike for her in good size. I planned to sell that Giant but then decided to try something strange: it was 27.5” but… maybe my 700c (28/29”) wheels will fit? They fitted and there was still a lot of space for bigger tires. Then I bought nice, custom-build 29” wheels using DT 350 hubs from second hand and also Gravelkings SK 700x50c tires. Still a lot of place, but with better comfort and higher speeds. After that transformation, it was 29” MTB with rigid fork. It was not enough for me…

Giant XTC 29" with rigid, carbon fork
Giant XTC 29″ with rigid, carbon fork

Time to handlebar and full gravel!

The last, but definitely the most difficult step it was to exchange flat bar to road/gravel handlebars and few other parts. I used GRX RD-RX810 1×11 rear derailleur with Sunrace 11-42T cassette. There was also a small change on the front, because 32T was not enough for me and I replaced its by 36T. Shifters: Shimano Ultegra ST685 with BR785 hydraulic brakes. Giant XR gravel handlebar and it was that: MTB converted to gravel bike.

Giant XTC Advanced Gravel Edition
Giant XTC Advanced Gravel Edition
Giant XTC Advanced Gravel Edition
Giant XTC Advanced Gravel Edition

What can I say after a few rides? It’s amazing bike. Looks like “gravel tank”, it’s real monstercross, but still very light (about 9.5 kg without SPD pedals) and very fast. Of course, riding it tires more than on CX/gravel bike with for example 700×32-35c tires, but there is a lot of comfort. And something… different. I have to use short stem, but it isn’t a problem for me. Replaced saddle, also replaced cassette to Ultegra HG800 11-34T because on my local area, is more than enough (and I still have 32T chainring). It was a good experiment. Probably overpaid – I could sell that bike as MTB and bought new gravel but… it wouldn’t be my “dream bike”, and that Giant is my dream bike. If you are interested in such conversion, let me know!

Final specification

  • Frame: Giant XTC Advanced, carbon
  • Fork: rigid, 100% carbon
  • Crankset: Shimano Deore XT M785 with 36T NW chainring
  • Real derailleur: Shimano GRX RD-RX810 1x11s
  • Cassette: Shimano Ultegra HG800 11-34T
  • Shifters: Shimano Ultegra RS685
  • Brakes: Shimano Ultegra BR785
  • Wheelset: custom-build using DT XM401 rims and DT 350 hubs
  • Tires: Panaracer Gravelking SK 700x50c
  • Seatpost: Accent Execute 27.2 mm
  • Stem: BTWIN 35 mm neutral
  • Handlebar: Giant XR Gravel
  • Pedals: Shimano M540 SPD

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