GRX levers, Tanpan, one of the new gen. Shimano MTB RD's, 5100, 6100, 7100, 8100, etc and an 11-51 cassette. With the 650b's, depending on size, will get you super close.

Tanpan

I bet you can run an 11-46 with the GRX800 RD and a Wolftooth Roadlink DM

RoadLink DM

I run a GRX 2x 46/30 with XT Di2 and and 11-51 cassette. The capacities can be stretched quite a bit if you know what to do.

 

Unless you'll be riding your gravel bike on the same trails as your mtb or you ride your mtb on gravel roads, I wouldn't worry about matching the gear ratio. Too many other factors come into play such as tires and road/trail surface.

 

Yes, and just like choosing the bike, delay gratification and figure out what gears are right for you. What you carry and where you ride can mean gearing like MTB, road, or between.

 

The weight difference between a gravel bike and a mountain bike is a small fraction of the total system weight, so there won't be a huge effect on gearing. If you are riding on the same slopes, you will likely want similar gearing to your mountain bike, maybe a little bit higher.

You will get a little bit of a reduction by using 650b wheels since the diameter is only about 95% of the diameter of a 29" wheel.

I'm running a GRX 2x (mechanical) and was able to fit an 11-46 cassette, and I could probably go higher by adjusting the B screw. I am using a Wolf Tooth RoadLink DM to clear the large sprocket. I also replaced the lower jockey wheel with a 16T pully to increase the capacity. I think the RoadLink will work with a 1x setup, and you probably won't need to mess with the pully size.

 

I run a 10-46 tooth cassette and a 38 tooth chainring (SRAM XPLR) with Wolf Tooth chainring. That’s why I’m on SRAM and not GRX. 46 tooth cassette. It’s not as low as my mtb but the terrain isn’t usually as steep. Plus gravel bikes climb better. Rigid and lighter. More air in the tires, not as big tire knobs.

 

I ride my hartail mostly on paved roads. 80% of the time. That's i wanted to build a gravel to catch up with my buddies. But I also didn't want to lose my advantage during climbs on paved roads. So I thought gravel could climb better with higher gear ratio.

 

Assuming your gravel bike has smaller tires, a more aero position, and a little bit lighter, it is going to be easier to push over those gravel roads at the same watts. So yes, you can (and probably should) choose a little harder gearing. A 40T chainring and 42T cassette is a very good starting space.

 

T

Thanks. 40T chainring with 42T cassette is i think still a bit too hard for me.

I am now considering an oval chainring. I have no experience with it yet. And it just looks odd to me. All i know is... when i get a 34T oval chainring, it is equivalent to 36T and 32T. I'm not sure on how would that help me on climbing.

Maybe others who has experience with oval chainrings can explain further.

 

On paved roads youll be able to climb steeper inclines. Big difference in rolling resistance. Theres some in less weight.
My trail bike s about 29-30 lbs and I run a 32 oval with 11-51 cogset. My "gravel" is about 24-25llbs with 30/46 oval and 11-34 cogset.
I do like oval, its not a dramatic difference, but I find I can generally turn a one higher rear gear at least. Previously I had round 30/46. On the same roads/trail I can use a higher gear.

 

I ride single speed mtb and gravel on the same single track trails. I use 34/15 gearing on the mtb and 42/16 on the gravel. Ride the same trails with about the same average speeds for whole ride unless I really push it then a bit faster on the mtb on single track. That all changes in gravel bike favor when on roads/gravel rides. I would go with the 40 tooth and 42 cassette on the gravel. You will work into it and need it in the long run.

 

Good lord that's steep. What is your singletrack like? Do you have tree trunks for thighs? I'm 38/19 on my CX race bike and that feels like hell 30 minutes into a race if there's a decent amount of climbing. I want to "race" in an upcoming 50 mile gravel event and was considering 38/17 as the steepest I would go. I top out at around 38/16 when I have the bike set up for pavement. It's been a minute since I did SSMTB, but I was keeping it steady at 32/20.

looks into the mirror

Am... am I a wussy?

 

I've never tried roadbikes or gravel bikes before. But someone told me that gravel bikes are lighter and easier to pedal than MTBs. He told me that with the same wattage I give on a bike, I could run smaller cog setting (or bigger chainring) on gravel than on MTB.

Is that really the case?

It's definitely the case looking at my XC race 29er vs. my enduro 29er. Road (grave) bikes magnifiy this.

 

Having had 4 different gravel or tour bikes in the family fleet I've found 2x is not as obsolete as I thought. In addition to wide range there are times when I'm not hunting for the right gear as much such as big wind and some climbs.

I don't view this stuff as right or wrong. I like 1x simplicity as much as I'm really pleased with GRX 2x crank and more road style crank.

 

I'm currently building a gravel bike (650b wheels) and I wish to have the same gearing ratio as my MTB hardtail. The GRX800 limits me to only 42T cassette and 40T chainring on a 1x setup. 2x is not an option to me.

I've never tried roadbikes or gravel bikes before. But someone told me that gravel bikes are lighter and easier to pedal than MTBs. He told me that with the same wattage I give on a bike, I could run smaller cog setting (or bigger chainring) on gravel than on MTB.

Given you have never ridden a road or gravel bike, I wouldn't be so quick to dismiss 2x.

It still has a place where people need a to have both high speed gearing for road/gravel, but climbing gears for steeper terrain.

1x is great and I love it its simplicity, but it is a compromise, especially at high speeds. On a MTB, usually you are at your fastest with the assistance of gravity on tight single track with less pedalling. On a gravel bike I find I am fastest under pedal power on road/gravel descents and with 1x GRX I can run out of gears, and then on the toughest of climbs, it isn't quite low enough.