Gravel and Cyclocross Crankset and Cassette Recommendations?

Hi, I am trying to figure out my drivetrain for a new gravel build I will be starting. I’ve got a T-Labs X3 (BB386 bottom bracket) frameset on order. I wanted to try to get some experienced people’s inputs. I am favoring for now, Shimano GRX 810 levers. Here’s the tricky part – is it possible to buy a crankset that can do both 1x and 2x setups? I like 1x for cyclocross (muddy Chicago CX Cup) but I believe I’d rather have 2x for longer gravel races (like Barry Roubaix or Dirty Kanza 100). And of course I want gearing for climbs as well as descents, so maybe about a range of about 418% gear inches or more. I’m thinking of starting with a 2x chainring with a 11-36 cassette. The GRX 2X has chainrings of 48 and 31. I believe for CX I can use just the small chainring, but it would need to be about a 34-36 so I won’t spin out, and I would need at least an 11-34 cassette.

<Question 1> Can I change out the small 31 chainring (80 BCD, 4 bolt) to a 34, 35, 36 chainring on the GRX FC-RX810-2? I couldn’t readily find an 11 speed 34, 35, or 36 chainring that I knew would fit on the GRX crank. I would also need an adapter or adapting bottom bracket to allow the BSA crank to work with the BB386.
<Question 2> Can I just buy a 46/36 crankset, e.g. FSA K-Force Light ABS Evo 386 Crankset 11sp, FSA SL-K ABS 386Evo 34/50, or FSA K-Force Light WE Crankset 52/36 386EVO. Something light and comparable to the GRX 810 cranks. Would it be easier/possible to change these chainrings to try to get something like 46-48 big chainring and 34-36 small chainring. I’m also concerned these older cyclocross chainrings will not have the 2.5mm outward adjustment like the GRX cranks which take into account that rear hubs are generally 142mm (and not 135). Is that 2.5mm significant for chainline?

<Question 3> Instead of 11-34 or 11-36 rear cassette, I’d love to have the smallest cog be 10 instead of 11. That would really expand the gear inches range. But I don’t think there would be a way to do it with an XD hub and 11 speed. Am I right?

I’m also open to any other recommendations for hybrid/mullet drivetrains: (A) Something with a lot of range (418% or more), (B) something that will allow me to keep from shifting chainrings when racing cyclocross, and (C) something without huge jumps between gears when trying to dial in cadence when gravel racing. Thanks in advance for your help.

Some references for gear inches, cadence, and speed below: 

I think the only 11 speed option on an XD freehub that isnt a 10-42 (or bigger) is eThirteen.  They make an 11 speed 9-34 cassette, plus its on sale!
https://www.ethirteen.com/products/xcx-plus-11-speed-cassette?variant=29367235084391

I use their 9-39 cassette on my 1x setup, shifting performance is decent, on par with the 10-42 SRAM cassette I was using.

I believe GRX was designed with the +2.5mm outward adjustment for increased tire clearance, not because of the 142mm rear hub spacing.  Because of this GRX cranks will likely only work well with a GRX Front derailleur.

If you dont want to be married to GRX, I would also look at Easton cranksets, super easy to swap chainrings, and lots of 1x and 2x options that will work with most drivetrains.

You might consider an Ekar 1 x 13 setup. There are 3 cassette options, and the shifting and brakes are superb.

For 1 & 2 - I would just buy a regular Shimano road crank, like 105 or Ultegra, and use the inner ring on that for your 1x setup.  Either that or buy a GRX 1x crank, and use that instead of messing around with another brand.

For 3 - you are correct, the cheapest/easiest way to get that 10 tooth cog is 11sp Xd driver

JWB475 wrote:I think the only 11 speed option on an XD freehub that isnt a 10-42 (or bigger) is eThirteen.  They make an 11 speed 9-34 cassette, plus its on sale!

https://www.ethirteen.com/products/xcx-plus-11-speed-cassette?variant=29367235084391

I use their 9-39 cassette on my 1x setup, shifting performance is decent, on par with the 10-42 SRAM cassette I was using.

I believe GRX was designed with the +2.5mm outward adjustment for increased tire clearance, not because of the 142mm rear hub spacing.  Because of this GRX cranks will likely only work well with a GRX Front derailleur.

If you dont want to be married to GRX, I would also look at Easton cranksets, super easy to swap chainrings, and lots of 1x and 2x options that will work with most drivetrains.

Those are good possibilities I wasn't aware of. With a 9-39 cassette, I could even possibly go 1X. I'm assuming that I would need an XD rear wheel? I'm assuming SRAM doesn't have anything 11 speed 10-32 or 10-36 or anything in between (I know they have 12 speed options which won't work, I'm assuming or maybe I can change some of the cogs?). Maybe with the 9-34, I would do a 2X.

The Easton cranks - does that easily allow you to do either 1X or 2X?? I don't think that's possible with the GRX cranksets, is it? I wonder if FSA BB386 cranksets can do both.

Also I believe that the RD-RX812 rear derailleur can only be used for 1X, but not 2X (not sure why). The RD-RX810 can probably be used for both 1X and 2X, is that correct?

Talabardio wrote:You might consider an Ekar 1 x 13 setup. There are 3 cassette options, and the shifting and brakes are superb.

1x13 sounds interesting, I guess in the same way that 1x12 sounds interesting as a possibility. Don't you think there is a rotational weight penalty associated with these big cassettes? I <<might>> be willing to consider SRAM in place of Shimano, but I've never heard of Ekar. Will look into it more.

clarksonxc wrote:For 1 & 2 - I would just buy a regular Shimano road crank, like 105 or Ultegra, and use the inner ring on that for your 1x setup.  Either that or buy a GRX 1x crank, and use that instead of messing around with another brand.

For 3 - you are correct, the cheapest/easiest way to get that 10 tooth cog is 11sp Xd driver

In the post above it mentions that the GRX being 2.5mm more outward - doesn't that give me the additional tire clearance; or in the reverse outlook, doesn't the road bike front derailleur decrease my tire clearance?

But 10 tooth cogs on 11 speed go minimum has the smallest big cog of 42 (i.e. 11-42 cassette), which would not be ideal for a 2X setup, but would be fine if I went 1X. Only SRAM 12 speed has the 10-32 cassette sizes which I assume cannot be adaptable to 11 speed.

Another option would be to switch out the GRX inner chainring to something like the XT M8000 SM-CRM91 mountain bike 11 speed, 34 tooth chainring. Does anyone know if that's possible? That would give me the right range of gears for CX, which essentially will give me a 2X while gravelling and 1x while CXing.

Also, just found this interesting article  https://www.ridinggravel.com/components/a-look-at-gearing-for-gravel-part-2x/

A 142 hub does not move the cassette outboard at all. It just adds to the end caps to sit on the “shelf” of the dropouts.
The cranks moving outward is solely to increase tire/chainstay clearance.
The current “norm” for road cranks is too far outboard for ideal drivetrain chainline and efficiency. Moving it out another 2.5mm just makes it worse. 

You could get a shimano Ultegra CX crank and swap out the little ring for a 34, then during CX season toss on a Wolf Tooth 1x ring.

I dont get why 48/32 is so perfect for gravel but 46/34 is unusable trash.

SRoad (a Chinese brand that sells on Alibaba Express) makes a one-piece machined steel 10-36 11-speed cassette, on XD pattern.  I bought one and have been riding it - $122 delivered, weighs 282g, shifts great.  It has machined shift ramps and good quality, trying to compete with the expensive Sram one-piece cassettes.   Seems not well known yet but the weight weenies forum is all about it.  Dunno if links will work - 

https://www.aliexpress.com/item/1005001303335077.html?spm=a2g0o.productlist.0.0.18a410ecCMAnFI&algo_pvid=null&algo_expid=null&btsid=0bb0623b16098763838768444efc87&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_

I'm running it with 46/30 crank on road wheels.  My local rides are steep up and steep down and I'm a borderline Clyde so this works for me. Looking at adding their 11-40 to my gravel wheels for this one local steep trail I haven't been able to get through without putting a foot down

I still miss the tight steps and wide range on my 3x10 touring bike setup but until there's a hydro triple this will have to do

fourfa wrote:SRoad (a Chinese brand that sells on Alibaba Express) makes a one-piece machined steel 10-36 11-speed cassette, on XD pattern.  I bought one and have been riding it - $122 delivered, weighs 282g, shifts great.  It has machined shift ramps and good quality, trying to compete with the expensive Sram one-piece cassettes.   Seems not well known yet but the weight weenies forum is all about it.  Dunno if links will work - 

https://www.aliexpress.com/item/1005001303335077.html?spm=a2g0o.productlist.0.0.18a410ecCMAnFI&amp;amp;amp;amp;amp;amp;amp;amp;algo_pvid=null&amp;amp;amp;amp;amp;amp;amp;amp;algo_expid=null&amp;amp;amp;amp;amp;amp;amp;amp;btsid=0bb0623b16098763838768444efc87&amp;amp;amp;amp;amp;amp;amp;amp;ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_

I'm running it with 46/30 crank on road wheels.  My local rides are steep up and steep down and I'm a borderline Clyde so this works for me. Looking at adding their 11-40 to my gravel wheels for this one local steep trail I haven't been able to get through without putting a foot down

I still miss the tight steps and wide range on my 3x10 touring bike setup but until there's a hydro triple this will have to do

how does it shift? It’s certainly not cheap, so maybe it’s an indication of the quality, but if it’s good it will be worth it! I will read the reviews on weight weenies. I wonder if it’s more trustworthy than e thirteen. E thirteen is pushing it with the 9 cog and I would be concerned about even greater loss in efficiency than the 10 cog. But at my level, it’ll probably be a relatively negligible factor

https://www.aerozinebike.com/products/transmission/crankset/for-road-bike/ 

To minimize the cassette jumps I think it would be a good idea to start with one of the smaller High-cog options. That way you're pulling down a bit the Outer ring tooth-count, which allows you to also bring down the tooth-count on the Inner ring. Thus not having to creep up in the cassette size (jumps). 

owly wrote:https://www.aerozinebike.com/products/transmission/crankset/for-road-bike/ 

To minimize the cassette jumps I think it would be a good idea to start with one of the smaller High-cog options. That way you're pulling down a bit the Outer ring tooth-count, which allows you to also bring down the tooth-count on the Inner ring. Thus not having to creep up in the cassette size (jumps). 

I think smaller cogs will shift better due to the smaller differences in diameter. However smaller cogs (and correspondingly smaller chainrings) will result in greater chain tension and wear.

youngjun91 wrote:

how does it shift? It’s certainly not cheap, so maybe it’s an indication of the quality, but if it’s good it will be worth it! I will read the reviews on weight weenies. I wonder if it’s more trustworthy than e thirteen. E thirteen is pushing it with the 9 cog and I would be concerned about even greater loss in efficiency than the 10 cog. But at my level, it’ll probably be a relatively negligible factor

It's a lot cheaper than the SRAM one-piece machined cassettes that are $300+, and similarly light...   but yeah more expensive than traditional (and heavier) stamped-cog cassettes.  One thread here:

https://weightweenies.starbike.com/forum/viewtopic.php?f=4&t=155158&start=75#p1585050

I had a sort of similar experience with the lockring - one of my tools works, the other one doesn't.  Never had a XD driver before the SRoad so I don't know if the same thing happens with other XD cassettes.  

Shift quality on mine is good, no difference I can easily quantify between the SRoad 10-36, Sunrace 11-36, Shimano 11-32 that I've used a lot.  The shift sound is different on each of these three but that's the most noticeable thing.  This is with a RX800 RD and DA9120 hydro/mechanical shifters.  

Efficiency loss in the seldom-used 12-11-10 cogs doesn't matter to me.  I don't race, I just ride for fun and usually have a long fast descent on most rides.  With 46 chainring I spin out the 11 cog.  One ride I could not pull at the front of a group on a long mild decline with 46-11 at 120rpm, they just rode around me with 50-11 and 52-11 on road bikes.  Big deal, I can stand to coast and get dropped if I have to, but it's fun to have the high gear I want.  Efficiency loss just isn't a factor (for me).

Be very careful with Shimano components.  I bought a Cannondale Topstone with 46/30 and 11-34 and I was looking to upgrade the rear to at least 11-40, better yet 11-42 because I encounter long, steep, gravel/dirt climbs.

The LBS I bought the bike from said no problem.  This experiment turned into a nightmare.   My LBS could not get an Ultegra rear derailleur to work with an 11-40 cassette.  One very knowledgeable member did seem to the this to work, which made me even more frustrated with my LBS.  I added a Wolftooth, which did not work because as designed, it can change the rear range, but not the rear-derailleur's total capacity.  Thus, unless I narrowed the front range, the 11-40 still would not work.

There is another option from Wolftooth -- their "Tampan", which allows the use of an XT rear derailleur.  I have not brought my bike in for this experiment -- I will report back.

If I had to do it all over again, I would have gone with a bike having a SRAM 10-50 rear.  I am not familiar with SRAM components and mix-max, and their full gravel gruppos seem expensive.

Not that I would, but you should be able to do it with the GRX 2x derailleur using 11-40 https://www.gravelcyclist.com/videos/shifting-big-gears-with-shimano-grx-2x-48-31-with-11-40-xtr-cassette/. I personally will try to keep it at 36 or less in the rear. Maybe with the XD options mentioned above. For now, I would like to stay away from extra parts like the Tampan, Roadlink, etc.

Also want to point out that I found yet another 11 speed cassette that may be an option:  https://us.3t.bike/en/products/drivetrain/cassette-579.html. FYI, it's usually much cheaper than the MSRP. Wish there were 11-speed 10 tooth options from SRAM/Shimano. I'll look into drivetrain efficiency losses for 9 vs 10 vs 11 tooth cogs and report back.

youngjun91 wrote:Not that I would, but you should be able to do it with the GRX 2x derailleur using 11-40 https://www.gravelcyclist.com/videos/shifting-big-gears-with-shimano-grx-2x-48-31-with-11-40-xtr-cassette/. I personally will try to keep it at 36 or less in the rear. Maybe with the XD options mentioned above. For now, I would like to stay away from extra parts like the Tampan, Roadlink, etc.

I saw that and did not look too closely.  This setup does not provided full range.   The 48t front is limited to the 35t cog on the rear cassette and the 31t front  looses the 11t and 13t rear cogs.

Am I missing something?


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