By Dede Barry

Shimano’s GRX drivetrain is the first dedicated gravel/adventure group set on the market. I recently spent a week riding and testing the Di2 version in Girona / Costa Brava and I came away impressed.

Prior to the trip, we assembled the 2x Di2 groupset on a Mariposa frame built with Columbus oversize tubing and a Whisky No. 9 thru-axle carbon fork that accepts fenders.   Shimano supplied us with groupset and the GRX 700C wheelset (WH-RX570-TL).

The bike was built with 48-31 chainrings and an 11-34 cassette, providing a wide range of options for varied terrain.

GRX Di2 has the smooth, accurate shifting that Shimano is well-known for and the rear mechanical clutch mechanism eliminates chain-slap.

Over the 9 days of riding at our Mariposa Cycling Tour in Girona / Costa Brava, the chain didn’t drop, slip or step out of line in any way.

The gear range is ideal for the steep climbs we rode in the foothills of the Pyrenees.  I had plenty of range from the gravel and single track inclines to the fast paved descents.

The GRX  Di2 RX815 levers are fantastic. The larger hood shape, lever shape and lever actuation are all unique to the Di2 model with other models having a much more traditional lever design. The hood/lever is one of the most comfortable I’ve used on any group.

The brake actuation combined with the 160/160mm Ice Tech rotor setup is the most impressive braking I’ve experienced from Shimano yet.

The GRX 700C  gravel wheels are up to Shimano’s usual standards when it comes to quality. With a wider tubeless rim,  tire flex is limited under hard cornering, providing added stability on rough surfaces.  I rode with Compass / Rene Herse Barlow Pass 700c x 38mm slick tires.  The bigger volume tire choice is brilliant when you’re riding on the rough terrain and, remarkably, being the only rider in our group with larger volume tires, I never felt I was working harder on paved road sections to stay at pace.

The PRO Discover bars with flared drops provide extra stability on the rough gravel descents, although, personally, I still prefer the standard bars on all other terrain.

Shimano has worked with Garmin to allow you to control your Edge head unit via the GRX Di2 levers, although I did not have this programed into my Garmin. Other options, such as 1x, mechanical (2x and 1x), 650B wheels, satellite shifters mounted on the top of the bars and sub-brake levers (BL-RX812) which run inline from the Di2 shifters and offer braking from the tops, just like cross-top levers of old are also available.

In an ideal world you’d have both 700C and 650B wheel options, as the 650B would allow you to ride extra wide (up to 48mm or 52mm tires depending upon your frame clearance) but that’s a bit extra money to spend, so my advice is to think about what you truly want from a bike before committing to one wheel size or the other.

Overall, my first impressions of GRX Di2 are very positive.

 

Specifications:

Frame: Columbus oversize tubing

Fork: Whisky No. 9 CX Disc Thru-Axle with fender mounts

Front Derailleur: Shimano GRX Di2

Rear Derailleur: Shimano GRX Di2

Crankset: Shimano GRX 172.5 with 48-31 chainrings

Levers: Shimano GRX Di2

Brakes: Shimano GRX

Rotors: Shimano GRX

Headset: Chris King Inset 7

Stem: Shimano PRO Vibe

Handlebar: Shimano PRO Discover

Seatpost: Shimano PRO Vibe Carbon Di2

Thru-Axles: Paul Compononents

Wheels: Shimano GRX WH-RX570 700C

Tires: Compass / Rene Herse Barlow Pass 700C x 38 mm Standard gumwall

Bottle cages: Shimano PRO Carbon

Saddle: Shimano Turnix Off-Road

Tape: Shimano PRO

 

If you are interested in upgrading to a GRX groupset, MRSP pricing is:

  • GRX 817 2x $3,173.31 CAD
  • GRX 817 Di2 1x $2,941.32 CAD
  • GRX 810 2x Mechanical $1,973.40 CAD
  • GRX 812 1x Mechanical $1,838.41 CAD

Groupset pricing includes derailleur(s), shifters, brakes, crankset, chain, cassette, bottom bracket, chain, rotors, and for the Di2 groups it also includes wires, junction boxes, battery, charger, etc.

For inquiries or to book a time to upgrade, please contact us at info@mariposabicycles.ca

 

 

Showing 2 comments
  • John Offutt
    Reply

    Hi Mike,
    If you were to compare this new Groupset to the previous Shimano build (ie. GTR Di2 1X or Ultegra GS Di2 2x) what are the specific differences in terms of performance and personality? Also, can you integrate the GRX parts with existing Shimano systems (ie. use the levers with existing GTR or add the GarX derailleur to your Di2 Ultegra setup)?
    Thanks for your review, experience and advice.
    John

    • dede
      dede
      Reply

      Hi John,

      The Dura-Ace Di2 Hydraulic groupset is lighter than the GRX Di2, but the upside of this GRX groupset in relation to the Dura-Ace Di2 groupset is the wider gear range, the comfort of the levers and in our opinion, slightly improved braking acuity. That said the components can be mixed and matched. If you want to discuss specific changes that you are interested in making, please give us a call +14164230456 or e-mail us at info@mariposabicycles.ca

      Thank you.

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