requesting opinion on recommended upgrade path for 1x CX bike for Gravel use

Hello All.  I'm currently running a Sram force 1x with 40T and 11/32 cassette on my CX bike.  I'm in the midwest and starting to dip my feet into gravel.  Going from Road, with a 50/34 11/32 setup, I definitely feel I'm working a lot harder.  what changes would you make for gravel use?  would I notice a difference going from 40T to 42T and stay with 11/32?

If you have the medium or long cage Force 1 rear derailleur, you can likely fit the Shimano 11-40 cassette in there. I would do that with a longer chain and keep your 40 tooth front. 40 x 11 is plenty on gravel and you will appreciate such a low gear for loose, steep climbs.

+1 on the recommendation from Dangle but I would am curious what situations are making you struggle?

NoCoGreg wrote:+1 on the recommendation from Dangle but I would am curious what situations are making you struggle?

My weak legs are my issue and nothing that can be fixed without proper training and or more gravel rides which I intend to do.  I was just wondering if the specs I have are fine.  I have one person running a 42t and 11/42 or 10/42 and swear by it.  someone else running a   46/36 and 11/30 rear.  just trying to understand if I'm limiting myself.  I don't plan on doing rides outside of the area.

NoCoGreg wrote:+1 on the recommendation from Dangle but I would am curious what situations are making you struggle?

"Midwest" is pretty broad, but if he's anywhere near the Driftless Region, there's ridiculous stuff. Think about barely maintained gravel roads with double digit kickers thrown in all over. I'm right around 4w/kg in peak form (not impressive, but not weak) and constantly find that 40 in the rear when riding gravel in the Driftless. That's why I recommended being able to drop down to a 1:1 in the rear.

Here's the profile from one of our favorite routes right in the IL/IA/WI corner.

 
6-7k of climbing in 70 miles with very little pavement is the norm out there.

I'm sure there's a calculator somewhere on the internet, but here are a couple equations for you to calculate your speed in any gear:

Gear_Ratio = Chainring/cassette-cog

So for a 40t chainring and 40t cog you have a 1:1 ratio

If the diameter of your wheel is 28" (roughly a 38mm tire on a 700c rim) and if you're pedaling at 90 rpm in the above 1:1 ratio (40t chainring and 40t cog) you'll be moving at 7.5 mph

If you shift to the 11t cog the ration becomes:
3.64

Your speed at a 90 rpm cadence is then:  3.64*7.5 = 27.3 mph

A 42t chainring will increase the gear ratio to 3.82 = 42/11
Speed at 90 rpm is now 28.65.

Similarly, increasing the chainring 2 teeth from 40 to 42 (5%) will make the low gear 5% taller (harder).

Also would going from 35 to 40 size tires help as far as gravel.  Currently running tubeless GK SK 35's.  Thanks for all the input today.

Fatter tires can certainly help if you have loose conditions.

However it's still not clear what your problem is. Do you a hard time climbing hills? Can't hang on the pack? Just feel slow everywhere?

Usually the limitations of a 1x drivetrains are:

1) Not enough range - to get a low gear for steep hills you don't have a high gear in other places.

or

2) Jumps between gears too big - when you have enough range the gaps between the gears feel too big. This can especially annoying if you're used to a road bike and ride in a lot of group situations where you're looking for the right gear to sit in the pack. Also at the higher end because of aerodynamics the jump between gears in terms of power are significant. If you're not in shape it might seem odd that you're good in one gear and then blow up trying to go faster by shifting up one gear.

Abepop wrote:
My weak legs are my issue and nothing that can be fixed without proper training and or more gravel rides which I intend to do.  I was just wondering if the specs I have are fine.  I have one person running a 42t and 11/42 or 10/42 and swear by it.  someone else running a   46/36 and 11/30 rear.  just trying to understand if I'm limiting myself.  I don't plan on doing rides outside of the area.

Ha! Welcome to the club!    As Greg LeMond once said, "It never gets easier, you just get faster."  

You're doing the right thing in checking to see what is working for other riders but also consider their riding style and strengths versus yours.  I ride with a bunch of small climbers who are spin monsters with cadences in the mid to upper 90's.  I'm 6" to 9" taller and my pedal style is more akin to a diesel engine.  In the hills they're in a small ring long before me and they have much lower gearing which means I stand and power up hills while they're spinning. 

I haven't tried a 1x setup for gravel but I was surprised how much I liked it mountain biking and will definitely go that way on my next mtb.  As Dwerby pointed out, the tradeoff in selecting gears is range versus the size of jumps.  

If your rides don't have many long steep climbs a cassette which is more tightly spaced (say 11-32 versus 11-40) will help you hang in with slightly smaller jumps between gears.  Similarly if you're falling off the back because you don't have a tall enough top gear, then I'd consider even jumping to a 44t front chainring.  But either of these changes will sacrifice lower gears. 

BTW, the one option I haven't spoken to is that of moving to a double chainring setup.  If you don't happen to have the parts, and if you don't have a good source of used parts, then adding a 2nd chainring can be very expensive.  Some frames designed for a 1x setup do not have a front derailleur mount nor do they allow for using a clamp-on derailleur because the frame tubes are not round.  At a minimum one will need to purchase a new left brifter (brake shift lever), chainring, cables and a front derailleur.

Greg

drwelby wrote:Fatter tires can certainly help if you have loose conditions.

However it's still not clear what your problem is. Do you a hard time climbing hills? Can't hang on the pack? Just feel slow everywhere?

Usually the limitations of a 1x drivetrains are:

1) Not enough range - to get a low gear for steep hills you don't have a high gear in other places.

or

2) Jumps between gears too big - when you have enough range the gaps between the gears feel too big. This can especially annoying if you're used to a road bike and ride in a lot of group situations where you're looking for the right gear to sit in the pack. Also at the higher end because of aerodynamics the jump between gears in terms of power are significant. If you're not in shape it might seem odd that you're good in one gear and then blow up trying to go faster by shifting up one gear.

I did the frostbite 40 this past weekend and granted the climbing was nowhere near the drift less region of the midwest, it kicked my ass especially in the hills.  I cramped up every single climb midway point so I was basically stopping every 2-3 miles to let the cramps subside.  The 20 mph wind plus occasional gusts did not help but I primarily suffered on the climbing.  I simply just ran out of energy.    

NoCoGreg wrote:
Ha! Welcome to the club!    As Greg LeMond once said, "It never gets easier, you just get faster."  

You're doing the right thing in checking to see what is working for other riders but also consider their riding style and strengths versus yours.  I ride with a bunch of small climbers who are spin monsters with cadences in the mid to upper 90's.  I'm 6" to 9" taller and my pedal style is more akin to a diesel engine.  In the hills they're in a small ring long before me and they have much lower gearing which means I stand and power up hills while they're spinning. 

I haven't tried a 1x setup for gravel but I was surprised how much I liked it mountain biking and will definitely go that way on my next mtb.  As Dwerby pointed out, the tradeoff in selecting gears is range versus the size of jumps.  

If your rides don't have many long steep climbs a cassette which is more tightly spaced (say 11-32 versus 11-40) will help you hang in with slightly smaller jumps between gears.  Similarly if you're falling off the back because you don't have a tall enough top gear, then I'd consider even jumping to a 44t front chainring.  But either of these changes will sacrifice lower gears. 

BTW, the one option I haven't spoken to is that of moving to a double chainring setup.  If you don't happen to have the parts, and if you don't have a good source of used parts, then adding a 2nd chainring can be very expensive.  Some frames designed for a 1x setup do not have a front derailleur mount nor do they allow for using a clamp-on derailleur because the frame tubes are not round.  At a minimum one will need to purchase a new left brifter (brake shift lever), chainring, cables and a front derailleur.

Greg

Loving the gravel so far.  it brings me back to why I started riding in the first place.  

Abepop wrote:

I did the frostbite 40 this past weekend and granted the climbing was nowhere near the drift less region of the midwest, it kicked my ass especially in the hills.

\n \nI was at Frostbite too! Great times. Not much climbing, but the ones straight into 20mph wind with sloppy wet gravel rivaled a dry, steep climb. Grab a Shimano 11-40 cassette and new chain (because you need a longer one with that bigger cassette) and you will be set. That cassette should fit your RD.