dpicare26

Was hoping for some advice on basic gearing considerations for gravel riding:



Yes, it's a cyclocross bike, but I won't be doing any CX races with it. I've got tons of awesome gravel roads locally, and many of them have some big climbs (one Cat 2, 3.3 miles at like 7%) that really kick my butt. Aside from the obvious (lighten up or get in better shape), what does the community recommend as far as gearing, and how I might most easily accomplish that with this current set up:

46:38T double
12:26 cassette (shimano 10 speed)
Dura Ace RD

It should be simple enough to change out the chanrings for something smaller, and should just be an FD height adjustment, right? Or do I have to consider the delta between sizes up front? is 46 already reasonable? (I certainly couldn't find the required gears for some of the climbing in the local state forest).

now, for the rear. I've read some people using shimano MTB cassette at the back. Noob question: would I then need a MTB RD? How do I know the range of cassette I could use with this current RD (I suppose that can be a simple google search)? And what ratio would you recommend?

I also take this on simple rail trails and that obviously well suited for that, but I'm more interested in being able to climb vs going fast on flats. (but if I kept the 46 that would be fine anyway).

Here's what I propose: go to a 46/30 chainrings (or should I go lower than 46?) and get some higher gearing at the back, perhaps more like 11-42 (depending on what else that does to hardware in terms of RD)

Any input would be appreciated.

aggiegrads

I don’t think that the crankset pictured would take a 30t small ring. If it does, swap it and you are probably done.

I have two bikes with 10 speed road controls and a nine speed mountain derailleur, that combination works great. You will not be able to use a ten speed mtn rear derailleur with road shift levers. Shimano changed the cable pull ratio for mountain with the introduction of ten speed.

if you have SRAM, you may be able to mix nine and ten speed road and mountain components, but I am not a sram expert.

HTupolev

You could use any Shimano 8-speed or 9-speed MTB rear derailleur, though.

dpicare26

So just keep existing RD and that should accommodate larger cassette?

Any advice on crankset/chainrings?

Edit: My mistake. Thought you meant any 8 or 9 speed cassette. That's good to know about the MTB RD, especially if I decide to go to a 9 speed cassette.

dpicare26

Meaning, the diameter of the inner bolts is too large for a 30t ring? Maybe I just look a new compact crankset, then?

HTupolev

I mean that an 8-speed or 9-speed Shimano MTB RD would work with your current shifters and a 10-speed cassette. Your 10-speed Dura-Ace shifters, paired to a 9-speed Shimano MTB derailleur, will happily shift a 10-speed cassette.

A 9-speed MTB rear derailleur paired with your Dura Ace 10-speed shifters will not index properly on a 9-speed cassette. You would need to also change your shifters to 9-speed if you wanted to do that.

mstateglfr 

Get a new crank with 48/32 or 46/30 rings.
Get a larger cassette like an 11-34 for example.

Figure out how much capacity your rear derailleur can handle and get a different one if the current one doesn't work.

zen_

If you're happy with the bike (other than the drivetrain), may as well just spend the money on a 10 speed GRX setup to use with your Dura-Ace shifters.

FC-RX600-10 46/30t crank
FD-RX400 front mech + braze on adapter
RD-RX400 rear mech- $62

You should be able to run up to an 11-40 cassette w/o issues, and there are many options for 11-36 or 11-40 cassettes. You'll also probably have to do some hunting to find the GRX stuff, ordering from Taiwan, and probably paying a bit over retail if you can find stock.

*Edit, you would need to use something like a Tanpan to make this work.

HTupolev

That won't work. Shimano changed their 10-speed road compatibility in 2015 when they launched Tiagra 4700, and that includes GRX400.

The cassettes use the same spacing as the old 10-speed standard. But, the rear derailleurs are now compatible with the new 11-speed road stuff. To make this combination work, the new 10-speed shifters pull a different amount of cable per shift than the old 10-speed shifters.

73StellaSX76

I just fitted a 46/30t bikingreen chainring set (look on eBay, about $85) on my compact crank for lower gearing. It uses proprietary rings. The quality is good, they pedal and shift smoothly. I do top out in the 46T big ring on the road, but I can live with that. I lowered the fd and shortened the chain. You’ll need to research your rd capacity to see which cassette range you can switch to. Just another option to consider.

HTupolev

The OP's crankset is almost certainly 130bcd, not a 110bcd compact.

73StellaSX76

Apologies, I assumed it is a cx bike and thought most came with 110bcd compact. Never mind.

zen_

I don't know why I always forget that the current Tiagra / RX400 uses the same pull ratio as 11 speed stuff.

caloso

A lot of CX bikes have been built up with older but still useable road components, which looks to be the case here.

dpicare26

I agree this is likely my best bet. Am I correct at stating that the smallest that will fit on a 130bcd crank is 38? So there's no wiggle room there for me. I'll look at compact cranks, and also look up what my current RD can handle. If I can't make much of a change w the current RD, I may go the route of a 9 speed MTB RD and a larger 10 speed cassette.

caloso

Yes, 38 is the smallest that will fit on a 130mm. I got this crankset for my CX: https://www.biketiresdirect.com/prod...cross-crankset. It's a hollowtech II, just like the DA one you have now, so it will use the same BB. It comes with a 46-36 which works well for me but you could certainly go smaller.

msu2001la

If you really want an 11-42 on the rear, you'll need a MTB RD.

In terms of what you can do with your current Dura Ace RD, I think you can run up to 28t max cog size without modification.
To go bigger, Wolf Tooth makes an adapter (called RoadLink) that may address this:https://www.wolftoothcomponents.com/products/roadlink

According to Wolf Tooth, a 10sp with Road Link will allow up to 11-40 rear cassette. It's worth noting that 11-40 10sp will have big jumps between gears so consider what you'll need and you might be better off with 11-34 or 11-32. Also worth noting that you'll still be limited by overall RD capacity, so your front gearing might need to be fairly narrow between small and big to make up for larger range on the rear cassette.

mstateglfr 

A subcompact crankset in 48/32 or 46/30 plus an 11-34 or 11-36 cassette will most likely get you all the gear range you need. It is enough for most riders in most situations and I would dare say its enough for most riders in all realistic situations they will be in.
Obviously everyone is different and there is no right or wrong gearing needs. <---a disclaimer so nobody needs to think i am gear-shaming.

The DA RD is almost for sure a short cage and not built to handle that large of a cassette. No harm in trying though if you want. If it doesnt work, then just get a Shimano Deore M591 RD and call it a day. Those things are simple 9sp RDs that index fine with any older Shimano external routed road shifters up to 10sp.

dpicare26

Yes I'm almost certain the RD will limit me to 29t max cassette. Is there any caveat to starting at the rear, and moving forward if necessary? Ie. changing the Deore RD and larger cassette and seeing how that plays out. The more I think about it, the more I feel like a wuss for crying that my granny gear isn't small enough . Either way, I'd be losing a DA component, and I think I'd rather keep the crankset if I had a choice. Any problems you foresee with trying the Deore RD and a 11-36 cassette and keeping the current cranks?

Edit: What I'm reading about the Deore is that it has a 36t capacity. Anyone use it successfully with up to 42?

Also heading the info about the Roadlink, and am sure I could get the Deore to stretch to 42 with that. Just curious if others have done without.

mstateglfr 

The m591 RD has a 45tooth total capacity.
46-38 is 8
36-11 is 25
25 plus 8 is 33.

33 is well under the max tooth total, so you are good there. And the m591 has an official max of handling up to a 34t cog, but Shimano is conservative and 36t large cogs are commonly used on RD with official 34t limits.

You should be good.

woodcraft

I just ordered one of those. Did the FD lower enough?

I have a similar condition as the OP- new (to me) bike has 46-38 chainrings. Setting it up to replace one that is a little big for me but have used for years.
With the 46/30 rings, a 110bcd crank to fit them, 11/36 cassette and either roadlink or the mtn RD off the old bike, I'll get lower than the 34:36 that I currently have,
and do better on steep & sustained Mt Tam terrain.

73StellaSX76

It did lower and it shifts fine.

dpicare26

Thoughts on the GRX FC-RX600 compact cranks?

mstateglfr 

I dont think I've read a negative comment on them from bike sites or forums.

The GRX crank sits further out from the frame by a couple mm, so pairing it with the GRX fd is good since its designed to be located further away from the frame.

Toespeas

the smaller the chain rings the less efficient you will get ,
it really comes down to your cadence and power , gravel is suppose to be able to go anywhere so you usually bring as many gears as possible , i think the 46 is fine but i would try to go as big a cassette as possible , at least a 36 if you can get 38 or 40 , it would not hurt .

you will need to get a mech that can pull those gears , i dont use shimano but its easy enough to find a mech that can do what you need , and at worst you will also have to get a new hub that can fit the larger cassettes , but you should be able to get a standard 38t at 10 or 11 speed .

i personally would go bigger with my chain rings maybe a 48 or 50 / 38 to 36 , for me the 38 and under are just too small and waste so much power , and i just made my cassette bigger , so now i have even more range and it feels great .
i also have been itching to try a 13 or 14 tooth to 38 cassette paired with a 40 or more ring but thats a full custom gear set up .
right now i run a 1x-39-11 to 36 and it handles everything its a bootleg set up with a clutch mech and a inner road chain , i race and gravel on it , works great for me
good luck