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Wide Range Gearing Question

Posted: Thu Jan 16, 2020 10:41 am
by The Cumbrian
I'm thinking of getting a gravel bike this year, but I'm not particularly enamoured with the gear ratios on any of the standard builds. In a perfect world (following my brief research)I would like a double chainring with 36 / 24 teeth (like a Sram GX 1000 GXP 11) with an 11 - 42 cassette, operated by drop handlebar brifters. Is this feasible, and if it isn't, what is the closest I could get? I'd rather have low gears than high gears.

I've used Sram as an example, but would welcome suggestions from any of the major manufacturers.

Re: Wide Range Gearing Question

Posted: Thu Jan 16, 2020 10:45 am
by Bearbonesnorm
I don't know about the brifters (someone will) but I run a mountainbike 36/24 double and 36t cassette on my Arkose. It's 10 speed (I don't yet trust 11 :wink: ) and I use bar end shifters. It's absolutely faultless and has more than enough range.

Re: Wide Range Gearing Question

Posted: Thu Jan 16, 2020 10:56 am
by whitestone
I had a demo on a Trek gravel bike and it was basically just a road bike with wider tyres, the gearing was 50/34 at the front and 11-32 at the back! Maybe fine out on the Kansas plains but, well - you ain't in Kansas anymore. :roll:

Have a play on http://gear-calculator.com/ for gear ratios. You can compare setups and most of the common cassette and chainring options are pre-loaded so it's just a case of selecting what you are after. You can do custom as well.

The limiter is really the derailleur. Once you've settled on the gearing you need to figure if there's a derailleur that can handle the capacity of the gearing and can handle the largest cog on the cassette. From what you said you need one with a capacity of 43T and can handle a 42T cog. Something like the Shimano SLX M7000 would do, though the max difference for the front chainrings is shown as 10T. 24/42 is a chuffin' low ratio - 0.66

The shifter just has to match the number of cogs on the cassette. Shimano and SRAM have different pull ratios so you'll need the shifters and derailleur from the same maker.

Re: Wide Range Gearing Question

Posted: Thu Jan 16, 2020 11:06 am
by ScotRoutes
It occurs to me that it's maybe gear ratios we should be using to differentiate between Gravel bikes and drop-barred MTBs.

I agree about standard gravel ratios. I've just rebuilt my VN Amazon with a 50/34 crankset and 11-40T cassette using an Ultegra rear mech. That's well outside Shimanos recommended limit but it works fine.

For my "gravel biking" usage that covers what I want pretty well. 24/42 would be proper MTB territory.

Re: Wide Range Gearing Question

Posted: Thu Jan 16, 2020 11:14 am
by Bearbonesnorm
I've long said the same thing Colin. Obviously 'Gravel' can mean very different things to different people but some manufacturers seem to have a limited grasp of the concept away from the marketing suite. I first built my Arkose up with a road compact up front and it was awful - over half the gears simply never got used. Sticking the mtb stuff on transformed it. I believe a gravel bike should broarden the scope not limit it but I suppose that depends on whether you're building a heavy road bike or a light mountainbike :wink:

Re: Wide Range Gearing Question

Posted: Thu Jan 16, 2020 11:29 am
by whitestone
Shimano are conservative (with a small 'c') about the stated max cog size but I suppose they're covering all bases and don't want complaints because someone tried something really extreme. IME you can go 2-4T more than what they say.

Across my MTBs the lowest ratio I have is on the fat bike with 26T front and 42T rear so 0.62 but it's really rare that I use it. My winter/commuter/gravel bike is 1x with 40T up front and 11-36T rear (10spd) and is probably a little under geared at the top and I could do with an extra gear at the bottom, 42T with 11-42T or 11-46T would be fine for me.

Re: Wide Range Gearing Question

Posted: Thu Jan 16, 2020 11:43 am
by Chicken Legs
I have got this Shimano set up on my Salsa ;

GRX 11 speed shifters

GRX812 Long cage derailleur

XT M8000 42 x 11 Cassette

XT M8000 Crankset 36/26t - 2 x 11

Re: Wide Range Gearing Question

Posted: Thu Jan 16, 2020 11:52 am
by The Cumbrian
Chicken Legs wrote:
Thu Jan 16, 2020 11:43 am
I have got this Shimano set up on my Salsa ;

GRX 11 speed shifters

GRX812 Long cage derailleur

XT M8000 42 x 11 Cassette

XT M8000 Crankset 36/26t - 2 x 11
That sounds just about perfect, thanks for that.

Re: Wide Range Gearing Question

Posted: Thu Jan 16, 2020 1:11 pm
by Lazarus
As noted above you will need MTB cranks for those sort of ratios and probably mechs but yes it dooable

Not really sure i see the point of a drop bar mtb - its just a more uncomfortable way of propelling yourself no faster than a MTB
If my cross bike is not faster it is not getting used for that or any ride.

Re: Wide Range Gearing Question

Posted: Thu Jan 16, 2020 1:29 pm
by pistonbroke
My brother in law has one of these. https://www.dolan-bikes.com/dolan-gxc-c ... build.html and with the double crankset 30/46 upgrade seems to offer a range of 30/34 bottom to 46/11 top. It has plenty of tyre clearance, lots of bottle and bag mounts and at c:£1800 fora full bike,seems good value.

Re: Wide Range Gearing Question

Posted: Thu Jan 16, 2020 1:32 pm
by ScotRoutes
Yeah, my #gradventourer has to be able to go places quicker and in more comfort than my MTBs allow, hence the higher end gearing. There's a point, off-road, where a proper MTB makes more sense to me. It just depends how many bikes you have/want and which niches they fill.

Re: Wide Range Gearing Question

Posted: Thu Jan 16, 2020 1:37 pm
by ScotRoutes
That Ribble page doesn't seem to let you choose a double crankset AND a 11-40 or 42T cassette. Seems sensible as that is way beyond Shimanos published limits and a retailer likely wouldn't want to offer that.

Re: Wide Range Gearing Question

Posted: Thu Jan 16, 2020 1:50 pm
by Mariner
I had a SRAM 2x10 on my Fargo with Apex brake/shifters.
I upgraded the cassette to a Sunrace 11-40 only because I was not sure if the 42 would fit without a link.
As it was the RD had a very long B screw so it would have taken the 11-42 easily.
As long as the front to rear gear teeth differences work with the derailleurs don't see a problem.

Re: Wide Range Gearing Question

Posted: Thu Jan 16, 2020 1:55 pm
by pistonbroke
Did you mean Dolan Colin? For the TNR last year, I built a setup using a Shimano hydro 11 speed groupset but changed the chainrings for Absolute Black 30/46 oval rings and the cassette for a Sunrace 11/40 cassette. I needed a wolftooth roadlink widget to get the 105 mech to clear the 40t sprocket but it worked with an 11/36, so it's marginal. It worked really well and having a narrower Q factor of 105 chainset and bb was a bonus, I didn't walk any of the steep loose sections, preferring to twiddle along at about 3 mph!

Re: Wide Range Gearing Question

Posted: Thu Jan 16, 2020 1:56 pm
by middleagedmadness
Just ordered a 38/28 Deore crankset , 11-42 cassette, a shadow plus rear derailleur, and some micro shift bar end shifters ,so I can start using my cdf around places it should be being used, think the whole set up came to £235 ,probably looking at put some Hayley brakes on it so I haven’t got the grifters on the bars anymore (I get confused easily and would be trying to change gear off the bringers not the bar ends )

Re: Wide Range Gearing Question

Posted: Thu Jan 16, 2020 2:03 pm
by BigdummySteve
I ran SRAM Eagle on the Fargo with a microshift bar end.

The 10-50 cassette range is huge, might it be possible to use an eagle mech and a double up front?

If only someone was selling such a setup ;)

Re: Wide Range Gearing Question

Posted: Thu Jan 16, 2020 4:31 pm
by ScotRoutes
Did you mean Dolan Colin?
Aye, bollocks. You can't choose a double AND a 40T cassette. My own experience shows it can work but I can understand a shop not offering it as an option.

Re: Wide Range Gearing Question

Posted: Thu Jan 16, 2020 5:58 pm
by PaulB2
There's a few video hacks on t'internet which use the newer 105 or Ultegra rear derailleurs with a 11-40 XT cassette, instead of the max 11-34 recommended, just by winding out the B-screw. Presumably it should work with the GRX derailleur too. When I replace the current cassette, my plan was to update my rear derailleur too as a cheap way to lower the bottom end.

Re: Wide Range Gearing Question

Posted: Fri Jan 17, 2020 1:00 pm
by marcinski
Chicken Legs wrote:
Thu Jan 16, 2020 11:43 am
I have got this Shimano set up on my Salsa ;

GRX 11 speed shifters

GRX812 Long cage derailleur

XT M8000 42 x 11 Cassette

XT M8000 Crankset 36/26t - 2 x 11
Interesting, what FD do you use with this?

Re: Wide Range Gearing Question

Posted: Fri Jan 17, 2020 3:00 pm
by wriggles
On my Camino I'm using an 11 speed GRX 30/46 chainset and 11-36 rear. Ultegra 6800 rear and Ultegra R8000 front mechs. Ultegra shifters. Perfect for everything around here and my weedy legs.

If I do TNR again I will swap the front chainset to an XT M785 24/38 with a 10 speed M780 front mech, and keep the 11 speed shifters and 11 speed rear mech/cassette. It works fine and the XT chainset gives me a lower gear than if I kept the 30/46 and put on a 11-42 rear cassette. The 38-11 top gear is plenty and when I spin out on that I am more interested in freewheeling and enjoying the view.

Re: Wide Range Gearing Question

Posted: Fri Jan 17, 2020 5:26 pm
by Chicken Legs
marcinski wrote:
Fri Jan 17, 2020 1:00 pm
Chicken Legs wrote:
Thu Jan 16, 2020 11:43 am
I have got this Shimano set up on my Salsa ;

GRX 11 speed shifters

GRX812 Long cage derailleur

XT M8000 42 x 11 Cassette

XT M8000 Crankset 36/26t - 2 x 11
Interesting, what FD do you use with this?
Shimano SLX M7025 Front Derailleur

£21 from Wiggle

Re: Wide Range Gearing Question

Posted: Fri Jan 17, 2020 8:20 pm
by marcinski
Chicken Legs wrote:
Fri Jan 17, 2020 5:26 pm


Shimano SLX M7025 Front Derailleur

£21 from Wiggle
Thanks, does it shift fine? Officially MTB FD and road shifter don't play well together.
I still think Shimano missed the ball with grx, they should have just made it compatible with MTB derailleurs from the start...

Re: Wide Range Gearing Question

Posted: Fri Jan 17, 2020 9:34 pm
by BigdummySteve
Both Shimano and SRAM have missed the ball, that ‘gravel’ might include big hills.
Eagle with its 500% range seems like the best option at the moment but has very limited shifting options on drop bars.
There are some closer ratio 12 speed cassettes available from the likes of rotor for example which when paired with an eagle or Shimano 12 speed mech might allow a close ratio 2X setup with a low bottom end, personally I don’t find the big jumps in the eagle cassette a problem off-road but when you hit tarmac you do notice it more.
I do miss my rohloff sometimes.
Part of the problem is the sheer versatility of bike like my Fargo, my 29+ ECR was dog slow on the road so I never ran out of top end, coupled with a 14 speed rohloff I always had a gear unless almost in free fall,
People who want to ride loaded drop bar bikes off-road up hills are few, we’re not got to get an off the shelf solution on the cheap because there really isn’t a huge market.

Re: Wide Range Gearing Question

Posted: Fri Jan 17, 2020 10:08 pm
by Landslide
It doesn't have to be spendy, or a massive problem for the manufacturers, we just need "road" and "MTB" components that work with the same pull ratios. They've managed it before...

Re: Wide Range Gearing Question

Posted: Fri Jan 17, 2020 10:11 pm
by Landslide
Also, while everyone is listing options, I may as well pitch in.

XT 40/28 chainset
11-36 10s cassette
105 10s shifters
Non-series Shimano 10s rear mech
Claris front mech, with a Jtek offset shim to push its chainline out a bit