Support road.cc

Like this site? Help us to make it better.

Back to Features
feature
How to
Tech
How to get ultra-low gearing for gravel bike adventuresgravel gearing 1

How to get ultra-low gearing for gravel bike adventures

Out of the box, gravel bike gears are too high. Here's how to sort them out
by John Stevenson
Sat, Feb 29, 2020 14:00
90

Want lower gears on your gravel bike? We do, so we set about combining some parts that aren’t supposed to work together to get a massive gear range. Ssshh, don’t tell Shimano.

Gravel bikes are over-geared.

Typical gravel gearing

Out of the box, your typical gravel bike has a 50/34 chainset and an 11-32 cassette, giving a range of gears that’s fine on roads unless you’re riding somewhere very hilly, but with limitations you very quickly bang up against when you venture off road.

That bottom gear is far too high. When I head out of Cambridgeshire to the gentle slopes of Suffolk I find myself wanting something lower for longer climbs. When he tested Trek’s new Checkpoint David Arthur — who is much, much fitter than me — found he had to get off and walk when riding the Cotswolds. "Compact chainsets have no place on gravel bikes," he said in a road.cc office discussion of the issue.

In gear inches that typical 50/34 & 11-32 set up has a low of 29in and a high of 123in — a 428% difference between smallest and largest.

Not only is 29in too high, but so is 123in. You’re never going to use that top gear off-road and you’re not going to get much use from it on the road either. (I could digress into a rant here about component makers supplying almost nothing but pro-class top gears on bikes that will never see a sprint for the line, but that's a topic for another time.)

Let’s try and cook up a better gear selection.

Sprockets

gravel gearing 4.JPG

The arithmetic of gearing makes a change of sprockets the most effective way to get lower gears, and in the last few years Shimano and others have made available 11-speed cassettes with ranges of 11-36, 11-40, 11-42 and even 11-46, all with the same sprocket spacing as our gravel bike’s 11-32.

But there’s a problem: no Shimano road derailleur is rated to work with a sprocket larger than 34-tooth. How about a mountain bike derailleur? Nope. For some reason known only to Shimano, their 11-speed road and mountain bike shifting systems aren’t compatible. Back in the nine-speed days you could use a Deore XT rear derailleur on a road bike if you wanted to, but that’s not the case for 11-speed. What to do?

Well, Shimano’s assessments of derailleur capacity have always been conservative. When Shimano say something won’t work, that often means it won’t work to the high standards Shimano sets, not that it won’t work at all.

And this is what we find with Shimano’s latest GS line of 11-speed 'Shadow' road bike rear derailleurs. The £58 Ultegra R8000 medium cage derailleur (RD-R8000-GS for fans of part numbers) is not supposed to be able to shift to a sprocket bigger than 34-tooth, but YouTube is full of backroom tinkerers demonstrating that it works just fine with an 11-speed 11-40 cassette.

gravel gearing 5.JPG

The 105 GS rear derailleur looks geometrically identical to the Ultegra, but is typically £20-£30 cheaper. Could this be a cheap way of getting really low gears on a gravel bike?

To find out, I bought a 105 RD-7000-GS rear derailleur (£36.95), an SLX CS-M7000 11-40 cassette (£40.77) and an 11-speed Shimano chain (£19.01). I thought about pushing my luck and going for 11-42, but I wussed out. Maybe another time.

The cassette is a big beast of a thing. I don’t think I’ll ever quite get used to just how huge a 40-tooth sprocket is, never mind the 50-tooth and bigger sprockets now available for mountain bikes. Rotor’s 13-speed system includes a 52-tooth sprocket. When Ah were a lad, that were a chainring!

The 11-40 cassette fits straight on the hub of my Prime RR-28 wheels in place of the 11-32, and the 105 R7000 GS rear derailleur substitutes perfectly for the 105 5800 GS unit. To give the derailleur the best chance of handling the big sprocket I dial the B-tension ‘angle of dangle’ screw all the way in, pulling the body of the derailleur as far back as it will go. I tweak limit screws and cable tension and run carefully up and down the gears.

Success! It shifts just fine to that huge sprocket, clicking into place as if it were designed to.

I’m still running the original chain, so I try shifting the front mech into the big ring. Bad idea. It’s immediately obvious that things are going to go seriously wrong if I try to use the big/big combination.

I ditch the original chain and fit the new one I’ve bought. At this stage I don’t have the chainset I want to use, but I want to ride this weekend. The existing chain would probably work fine with the 46/30 chainset I’m waiting for.

Out on the road and the trail, the difference is soon obvious. I keep glancing down, thinking I must be getting close to the lowest gear, and finding I’m actually in the middle of the cassette.

This isn’t very surprising. The 34/25 combination on the old set-up, 37 gear inches, was two gears from the lowest. In the new set-up’s 34/24 (38.3 inches) I still have four lower gears.

My proving ride takes riding buddy Al and me down a narrow, wet bridleway into the village of Linton, home of the excellent Linton Kitchen cafe. We’re in the middle of a drought, but the leaky water tower at the top of the hill means there’s always a stream here to flick mud up at you.

Fuelled by coffee and carrot cake, we tackle the bridleway in reverse. My state of fitness could be accurately described as woeful, but nevertheless, it’s a doddle. The average gradient of the top section is about 10 percent, which by Cambridgeshire standards makes this a Proper Hill™, and climbs on trails never have perfectly even gradients. I pootle up it easily. Al zooms on ahead. Not having a 34/40 low gear he doesn’t have any choice, I tell myself. It’s nothing to do with him being a lot fitter than me. Ahem.

For fans of gear charts, this is where we started:

  11 12 13 14 16 18 20 22 25 28 32
50 122.7 112.5 103.8 96.4 84.4 75.0 67.5 61.4 54.0 48.2 42.2
34 83.5 76.5 70.6 65.6 57.4 51.0 45.9 41.7 36.7 32.8 28.7

 

And this is where we are now:

  11 13 15 17 19 21 24 27 31 35 40
50 122.7 103.8 90.0 79.4 71.1 64.3 56.3 50.0 43.5 38.6 33.8
34 83.5 70.6 61.2 54.0 48.3 43.7 38.3 34.0 29.6 26.2 23.0

 

In short, we’ve stretched the range from 428% to 538% with no downside except for a bit of extra weight. I think the gaps between gears are still reasonable; more on that later.

To go even lower (and wider) we’re going to need a change of chainset.

Chainset

One thing I wanted to avoid in this project was trying to persuade road and mountain bike components to work together. There was a time when you could cross the streams easily, but Shimano’s road and off-road derailleurs now have different geometries, so you can’t use mountain bike mechs with road shifters without some sort of cable pull converter. That’s a level of bodging I wanted to avoid.

gravel gearing 6.JPG

That means the chainset can’t be too small or a road front mech won’t work well with it because the curves of the cage won’t follow the shape of the chainring. I therefore settled on one of FSA’s Adventure chainsets in a 46/30 'sub-compact' configuration. That’s enough of a difference to be worth the hassle, but not so much that the shifting will be balky.

FSA makes several 46/30 cranksets, from the high-zoot K-Force and SL-K Modular units with carbon fibre arms to the inexpensive Tempo CK Adventure cranks that fit old-school square taper bottom brackets. In the middle, at a sensible price and weight, there’s the new Energy Modular BB386 Evo crankset (£200), with hollow forged aluminium arms, so I went for one of those.

gravel gearing 3

Fitting was straighforward, with just one caveat: the position of its mount stopped the front derailleur going quite as low as I’d have liked. The front derailleur cage ended up a couple of millimetres higher than Shimano recommends.

That’s another reason not to use a mountain bike chainset. If you have a braze-on front derailleur it’s unlikely you’d be able to get it low enough for the 38-tooth outer of a typical mountain bike double — and of course you probably want a higher top gear than the 38 ring would provide.

The gear range

With the FSA 46/30 chainset, the resulting gear range is massive. Here’s what it looks like:

  11 13 15 17 19 21 24 27 31 35 40
46 112.9 95.5 82.8 73.1 65.4 59.1 51.8 46.0 40.1 35.5 31.1
30 73.6 62.3 54.0 47.6 42.6 38.6 33.8 30.0 26.1 23.1 20.3

 

That’s a 558% range, much bigger than the 428% we started with and most of the extension is at the bottom of the range where it’s most needed. But we’ve also preserved a decent high gear for those zoomy road descents.

Only mountain bikes have lower gears. While single-chainring gearing has all but taken over on mountain bikes, some double-chainring bikes are still available, with gearing down to a positively wall-climbing 22/42 (around 15 inches, depending on wheel and tyre size).

Those systems sacrifice the high end though. With a 36/11 or 38/11 top gear (around 90 inches) you’re going to be doing quite a bit of coasting on descents.

Riding

Out back, the 105 rear derailleur clicks effortlessly and without fuss from one sprocket to another, even when it gets to the final 35 and 40-toothers that it's not supposed to be able to handle. Up front, the old 5800 front mech flips easily between the 46 and 30 chainrings.

This set-up is noticeably gappier than the one it replaced. There are a couple of 15 percent jumps between gears, and the gap between the two highest, provided by the 11 and 13 sprockets, is a whopping 18 percent. I can live with that, but if you're a finely-tuned pedalling machine who struggles to change cadence more than a few percent, you're going to find it a bit jarring.

The big advantage of a gear set-up like this is that it reduces the need to hit the redline every time you go uphill. Back when I was doing a lot of mountain biking, I was always the guy pootling along at the back while everyone raced up the first couple of hills. And I was the one with plenty in the tank at the end of the ride, sitting on the front towing everyone for the last 10 miles home.

Tweaks and alternatives

If Shimano's 11-40 cassette is just too gappy for you, SRAM makes an 11-36 11-speed cassette (£63.05) that shrinks the biggest gap by dropping a 12 between the 11 and 13. With a sub-compact chainset like the FSA that still yields some usefully low gears. SRAM says the 11-36 is only compatible with single-chainring gear systems, but that's almost certainly a matter of marketing rather than engineering.

If you wanted to go electronic, you could assemble a Di2 version of this transmission without breaking any of Shimano's rules. The XTR and Deore XT electronic rear derailleurs work with Ultegra and Dura-Ace Di2 drop-bar shifters. The Di2 rear derailleurs are rated for a 42-tooth sprocket in a 2 x 11 system, so you could go slightly lower than I have. I'd love to hear from anyone who's tried this.

WolfTooth RoadLink

If you wanted to save money, you could use a £22.95 Wolf Tooth Roadlink to extend the capacity of your existing rear derailleur. According to the manufacturer, the Roadlink will extend any non-Shadow GS rear derailleur to work with an 11-40 cassette.

That'll work if you're still running 10-speed too. SunRace makes a couple of 11-40 10-speed cassettes, the £30.59 MS3 and lighter MX3 (£40).

Conclusion

I think the system I’ve put together provides the best wide-range gravel bike gearing currently available, at a sensible price. It's very handy that it can be put together in two stages and the most effective one — changing the sprockets — is the cheaper.

There are plenty of arguments for alternatives, though. People fitter than me like the simplicity of 1 X 11 systems and are prepared to sacrifice a bit of range to get an easy life, and more power to them.

It's a pity Shimano doesn't make it easier to put together a wide-range system like this. They could offer SGS versions of the Ultegra and 105 Shadow rear derailleurs, for example, with the capability to handle 11-40, 11-42 or even 11-46 cassettes. And they need to offer chainsets with smaller rings and front derailleurs that work with them. Maybe next year, eh?

gravel bikes
adventure bikes
gearing
low gears
John Stevenson

John has been writing about bikes and cycling for over 30 years since discovering that people were mug enough to pay him for it rather than expecting him to do an honest day's work.

He was heavily involved in the mountain bike boom of the late 1980s as a racer, team manager and race promoter, and that led to writing for Mountain Biking UK magazine shortly after its inception. He got the gig by phoning up the editor and telling him the magazine was rubbish and he could do better. Rather than telling him to get lost, MBUK editor Tym Manley called John’s bluff and the rest is history.

Since then he has worked on MTB Pro magazine and was editor of Maximum Mountain Bike and Australian Mountain Bike magazines, before switching to the web in 2000 to work for CyclingNews.com. Along with road.cc founder Tony Farrelly, John was on the launch team for BikeRadar.com and subsequently became editor in chief of Future Publishing’s group of cycling magazines and websites, including Cycling Plus, MBUK, What Mountain Bike and Procycling.

John has also written for Cyclist magazine, edited the BikeMagic website and was founding editor of TotalWomensCycling.com before handing over to someone far more representative of the site's main audience.

He joined road.cc in 2013. He lives in Cambridge where the lack of hills is more than made up for by the headwinds.

Add new comment

90 comments

Avatar
andyspaceman | 5 years ago
0 likes

Fabulous article.

To throw my twopenn'oth in:

- Not quite as compact as FSAs 46-30 chainsets, but absolutely brilliant are Praxis Works 48-32 offerings. Fitted a 48-32 Zayante to my gravel bike a couple of weeks ago, and am blown away by how stiff both the cranks (power transmission) and the rings (shifting) are. The 50-34 Shimano Sora unit they replaced was 'fine' and cost a lot less, but it's like chalk and cheese.

- I think double chainring is still where it's at for any gravel bike that might be pressed to bikepacking/touring/other-load-carrying duties. I'm a big fan of the single chainring on my mountain bike, but when faced with a draggy off-road climb whilst carrying kit, I want low gears AND small-ish gaps between them. Only a double (or even a triple!) with a dedicated granny ring is going to offer that, assuming that a sensible high hear is also a requirement.

 

Avatar
reippuert | 5 years ago
0 likes

50/34 - 13/40 gives you a decent range for gravel and bikepacking.

When i build my current gravelbike only subcompact options for non taper square cranks with a road q factor was the in Europe unobtainable Sugino OX2-901D

Middleburn had the  RO2 Road X Incy but went out of business as i assembled the bike and still tried to source ideal parts. White industries was still vaporware - So i setteled with a Chorus 50/34 from my stash. 46/30 - 12/36 would have been my prefered choise though.

 

 

Avatar
Bendurance | 5 years ago
1 like

I’ve been running SRAM Force 1 with a Garbaruk 10-50 cassette on my gravel/monster-cross bike for almost a year now. No need for MTB RDs, shifting has been perfect with Force 1 RD and the replacement cage that comes with the cassette - just as smooth as Ultegra on my road bike.

I use a 38t chainring for day-to-day use on road and off-road (which gives me a more than sufficient top speed of 50kmh), and switch down to a 34t chainring for loaded bikepacking (SRMR last year and Italy Divide at the end of the month). 

Even on a 200km road ride the gaps rarely bother me - the bottom of the cassette has close spacing, the middle is ok as long as you have a reasonable cadence range, and the large gaps at the top are not noticeable when going that slow. Others may hate it. 

I will definitely run 1x for TCR this year. Either the above setup or possibly 38x 10-42 if training goes well. In the longer term 12 or 13 speed 10-50 cassette is where its at for me and covers all of my riding.

Avatar
Echo | 5 years ago
0 likes

Nice links to online advertisers websites, that will keep you guys going for a while.

Avatar
gary p | 5 years ago
0 likes

Soo...inquiring minds want to know if the rear derailleur actually had enough wrap to crosschain big/big (46/40) once the longer chain was on.  That's always the larger concern than rear cog clearance.  

 

As for the issue with the front derailleur not having enough downward adjustability on a hanger envisioned for nothing smaller than a 50/34, there is a way to bring the chainring "up" and still have the 46/30 gearing you want: ovalized chainrings.  ROTOR's new Aldhu or Vegast can be paired with a nice Direct Mount 46/30 Q-Ring.  

Avatar
gary p | 5 years ago
0 likes

Soo...inquiring minds want to know if the rear derailleur actually had enough wrap to crosschain big/big (46/40) once the longer chain was on.  That's always the larger concern than rear cog clearance.  

 

As for the issue with the front derailleur not having enough downward adjustability on a hanger envisioned for nothing smaller than a 50/34, there is a way to bring the chainring "up" and still have the 46/30 gearing you want: ovalized chainrings.  ROTOR's new Aldhu or Vegast can be paired with a nice Direct Mount 46/30 Q-Ring.  

Avatar
TimB34 | 5 years ago
0 likes

Been meaning to mention this for a while.. 

Although the article says "The 11-40 cassette fits straight on the hub of my Prime RR-28 wheels in place of the 11-32", shimano 11-speed mtb cassettes are actually 1.8mm smaller than shimano 11-speed road cassettes. A lot of freehubs are short enough that you can screw the lockring tight enough and never notice, but the new mtb cassette will be nearly 2mm too far inboard.

I followed the same path from 11-32 to 11-40, but shifting was a bit noisy. I eventually worked out that a spacer was needed and added one. The cassette didn't seem any tighter on the freehub, but shifting noticeably improved.

Avatar
Tones0000 | 5 years ago
0 likes

Thinking about the Di2 route but coming from the other direction - rather than trying to squeeze a road rear derailleur around a MTB cassette: Does anyone have thoughts or experience running 46/30 chainrings on an Xt di2 front derailleur? 

A couple of possible issues:
Is the 16T jump too large for the MTB derailleur?
Is there a problem with the BB length (68 vs 73mm)?

Other issues?

Thanks

Avatar
kiwi_gravel | 5 years ago
0 likes

If anyone is searching for slightly weird combination of kit ..... I have been running RX800 with 11-42 Xt cassette (Ultegra shifter) on my Exploro  for past month or so. Loving the setup but having a bigger range of the SRAM XX1 10-42 would be ideal for singletrack playing.

So I rigged up a SRAM XX1 cassette onto XD freehub 650b wheels, adjusted the B tension screw (had to fully screw it in), and I now have 10-42 with 42 tooth chainring up front.  

FYI, I run SRAM XX1 mtb cranks with Wolftooth 42tooth narrow/wide chainring.

 

 

Avatar
kiwi_gravel | 5 years ago
0 likes

*duplicate

 

 

Avatar
Nanolight006 | 5 years ago
4 likes

Another option which is cheap and works extremely well is to use an extender for the derailleur hanger. This lowers the derailleur by about 22mm to accommodate a bigger cassette. 

I'm nearly 60 and live in Sheffield, riding in the Peak District with some beautiful but cruel climbs.

I decided to extend the gearing range on my Planet X Nanolight using the extender bought for £2.89 on eBay coupled with a 33 tooth ring from TA Specialities also from eBay.

I now run a 52-33 chainset with an 11-34 cassette with the original 108 link chain. Deraileur is 10 speed Dura ace with short cage.Shifting is still superb front and rear and I can use all gears from 52-34 to 33-11 reliably.  I think it could even be pushed to 11-36 !

The only tweaks required were simple : -  adjust b-screw to suit, and lift front derailleur about 5mm to clear slightly higher chain line as it just fouled underside of top of cage.

So all easily available parts and hardly any work at all required. Just goes to show how very conservative Shimano specs rreall are !

 

Hope this is useful to somebody.

Avatar
Tones0000 | 5 years ago
0 likes

I assume everyone has now seen the Shimano GRX series with 48/31 and 46/30 cranksets. The big question will be whether we can bodge an 11-40 or hopefully an 11-42 cassette onto the GRX long cage rear derailleurs which are officially rated for a maximum sprocket of 34T (36T on the 10 speed) and 47T capacity (like everyone has done on the recent road derailleurs).

Avatar
whizwith | 5 years ago
0 likes

I had my LBS put on an XT M8000 11-40 on my Lynskey R260 R8050 Di2 setup . I was hoping to use an FSA 48/32 up front, but the frame can't do it with the Di2 wires in the BB. But the LBS said they could replace the 50 with a 46. So I have 46/34 up front, and 11-40 in the back. I need to go for more than a spin and shall report back but was looking for help - How should I adjust the synchro shifting? Is there a logic to the defaults Shimano uses for the 50/34 11-34 setup I had on there before? If someone can point me to a chart or something that explains the framework, I'd be grateful! Thank you

Avatar
whizwith | 5 years ago
0 likes

CXR94Di2    Thank you!

I did have a follow up. So when I went into E-Tube the default settings for my old setup (34/50, 11-34) is listed in "A". The crossover points are color coded where blue is when shifting down, and the green is when shifting up. The red blocks are the combinations that are locked out (not sure if that is the right term).

If I understand the chart you provided and applied it to the new setup (34/46, 11-40), the shifting up setting would start in one of the locked-out settings. This is illustrated in "B".

If I were to apply the logic of when shifting to a harder gearing to shift it such that it is in the next hardest ratio, I come up with the scenario in "C".

Is this right or am I not going about this the right way? The combination I'm using is not available in E-tube, so I am using the old setup but applying crossover points using the gear ratio tables you recommended. Where would you set the crossover points when shifting up from the 34 ring if cogs 11 and 13 were not available.

Should I instead try to find a combination in E-tube that does not lockout the 11 and 13 cogs while in the 34 chainring?

Thank you so much for your help!

 

Avatar
CXR94Di2 | 5 years ago
0 likes

B table looks correct as mine.  The actual numbers arent available within E tube look up tables, so you have to find the ratios from the likes of Bikecalc and use gear positions instead, the method works fine.

You will see that you can only jump so far with rear derailleur settings as the E tube setting block wide cass jumps-have a play, folk have different gearing preferences.  Using 34t chainring with 11t cog is cross chaining and not recommended for increased chain wear and potentially more likely to jam up chain or snag derailleur- same for 46t with 40t cog.  

I use syncro shift to primarily keep my chain more inline, but its a nice little feature to use-you can toggle back to manual mode if you dont like it or particular style of riding is interferred with syncro-I mean certain gear selection for a section of road finds you jumping up and down the front derailleur too often.  I find this on steep climbs where the ratios im using sometimes have me spinning or grinding with front derailleur moving between granny chainring and middle ring

Avatar
KoenM | 5 years ago
0 likes

I just bought a Gravelbike from Ribble, but as I use it 80% of the time as a winter roadbike therefor I have 2 sets of wheels 1 with 11-32 and 30mm tires and one with 11-34 and 38mm tires so I can easly change it without having to adjust it. If I ever will use it more for gravel I probably buy a new Shimano GRX RX810 48/31 crankset so I would still have enough of a high gear and alot lower than the 50/34 I now have, but as I said before that will only be if I go gravelriding more.

Avatar
iandon | 5 years ago
3 likes

I manged to get a Sram 11 - 36 working on my  50 - 34 chainset with ultegra rear mech by swapping the top jockey wheel to 10 tooth instead of the 11 tooth standard.  I have now got the clearence for it to shift across the full range.

Avatar
kil0ran | 5 years ago
1 like

Inspired by this article and the recent review of the Miche Graf chainset I've just upgraded my Fairlight Faran. This has been set up for a while with 40mm WTB Nanos, 50/34-11/28 on Tiagra shifters, 105 chainset, and R7000 front mech. So a proper frankenbike.

I've now shifted this to an FSA Tempo Adventure 46/30 with the Tiagra 12-34 cassette (already had the Tiagra long-cage mech). I really like the look of the Tempo Adventure and have made peace with installing a square taper BB - this bike isn't about getting the weight down.

Despite the drop from 50 to 46 I haven't needed to drop the front mech. It's way out of Shimano's tolerances but shifting is absolutely fine - I'm amazed that I didn't even have to tweak the cable tension. FWIW the Tempo with a 118mm axle maintains the same chainline as the 105 with a Hollowtech BB.

Very noticeable difference on the couple of rides I've done so far. I'm spending a lot more time in the big ring on the roads but being able to stay seated on offroad climbs is fantastic. Need to get fitter because I find I can't spin a granny gear at a high cadence for long enough for some of my climbs - long, deep-rutted chalky/flinty stuff on Cranborne Chase/Salisbury Plain. Also need to get better at bike handling! Riding slow in ruts surrounded by nettles and thistles is tricky!

Has really re-energised my cycling though. I've also swapped to a Brooks Flyer saddle which I find really suits me and I've started riding in plain clothes as it were (i.e. no padded shorts)

Wondering if I can swap the 12 ring for an 11? Not really necessary on the WTB Nanos as they're so draggy on the road and I'm not doing long distances but I do find I spin out the 46/12 if I'm feeling like smashing it. Doesn't help that my run back home from my usual haunts is pretty much downhill. 

Avatar
kil0ran | 5 years ago
1 like

Question for the experts in this thread, why do the Shimano rear mechs have a minimum big cog size?

For example, the new RX810 list min/max big cog size as 30/34. The RX400 is 32/36. And the RX-812 is 40/42.

Is it because they're clutched mechs?

Avatar
Sparkyspice | 4 years ago
3 likes

11-42T + 46-30

I bought a Trek Checkpoint ALR5 and wanted to do some light touring.  I then got the bug and bought front and rear racks and panniers.  I can carry camping/cooking kit, clothes/food etc for extended trips.  The extra weight means more gearing was required from the stock 11-34T cassette and 105 50-34T chainrings.

After much research I went for Absolute Black 46-30 oval sub compact chainrings, which were a doddle to set up with the standard 105 front mech.  The advantages of oval rather than round are a moot point for some, but I 'think' I feel a difference!  We'll see when I do some proper touring on this set up!

I swapped the 11-34T cassette for a 11-42T.  This was a bit of a leap of faith.  I knew (having read this article above), that a 11-40T would work, but I wanted to get as much as I could so I gambled with a 11-42T.  I had to swap out the 105 rear derailleur for an Ultegra GS (medium cage) derailleur and as I was putting it on my gravel bike, I went for the RX model with the switchable clutch mechanism.

It works!

I had to use pretty much all of the 'B-Screw' adjustment, but everything else was plain sailing with the set up.

GEARING

LOWEST GEARING with 35mm tyres

ARANGEMENT                                INCHES

Checkpoint STOCK                      27.24     (34F/34R)

105Chainset 34/50 36T rear     25.61    (34F/36R)  (Current bike)

Absolute Front 30/46 +36T       22.61      (30F/36R)

Stock Front + Rear42T                22.00    (34F/42R)

IDEAL setup           30F 42R         19.40    (30F/42R)

 

Cost - 

Absolute Black rings 30/46                          £145

XT 40T Cassette          CS-M8000-11            £60

Ultegra Rear Mech         RD-RX-800-GS      £67

Ultegra/XT Chain         HG-701                      £19

                                                                                  £291

 

This seems expensive, but you have to replace a worn out drivetrain at some point, and the clutch mech works really well off road.  I can now ride up 14% climbs fully loaded and remain seated and spinning.  For me - it's worth the effort and cost.

Avatar
MICHELEd | 4 years ago
0 likes

This paper gave me the confidence to have a 11/40 cassette fitted on my grx 11 bike instead of the stock 11/32. Thank to the Author.

Works nicely, but I didn't dare try the big-big combination!

Avatar
Pfaff | 4 years ago
0 likes

A little bit outdated, isn't it?

Thinking of the GRX...

Anyway, I rode a good part of the TNR-diy this last september using a FSA 46/30 crank and a SRAM 11/36 cassette, Force 22 front and back long cage mech on my Mason Bokeh all inspired by this article. Bike worked a treat. I didn't.

 

Avatar
Curtis | 4 years ago
0 likes

I have 8 speed on my triban and climbing is a pain as I live on the border of the dales & the forest of bowland. I'd love to get more gears but this seems way too confusing for me to manage without having a stroke lol

Avatar
AmsterDan the A... | 4 years ago
0 likes

This was such a great article and one I wish I'd had access to quite a while back when I was trying to figure things out.  I didn't realize that you could pair XTR and XT with Ultegra Di2...I thought that wasn't possible, or, did I misunderstand?

I ended up going with a Rotor direct mount crankset.  Easy to swap out either a 50/34, 48/32, or 46/30.  I run that with 11-speed Ultegra Di2 GS cage and a Sram 11-36 cassette.  I can use this on either gravel or regular road riding.  On the low end, the SRAM Cassette paired with the 48/32 offers me a more useable range of gears when riding on the road and in the hills.  With the 32 upfront, I have a 36, 32, 28, 25 in back - 4 gears for climbing.  These ratios make more sense as I get older and also allows me my cadence between 60-110 and I now have options to actually vary my training in the hills.  I wish I could give up a gear or 2 on the high end...a cassette 13-36(38) would be possible and makes more sense since I'm not bombing downhill.  I try to avoid hospitals these days. 

Avatar
Nickthedangerous | 4 years ago
0 likes

This is super helpful.  Question with regard to my bike - I bought this funky Slingshot gravel bike and want to replace my cassette and I assume, RD . It has Dura Ace 7801 shifters, crankset is a 50/34 with a FD 7800, and currently riding a CS 6700, I believe it's only a 11-28.  If I were to replace  my RD to a  GS, and keep my 50/34, would this 11-40 work? Would I need to buy a 11 speed chain so it'll go over the 50? My two thoughts are: 1. will my shifters work with whatever mod I do, 2. I am debating keeping my 50/34, so just making  sure my 10 speed setup is going  to work with the 11 speed chain and only modifiying the RD and cassette to a 11-40. Actually, third thought - think I could actually do the 11-42 on the back? Thanks in advance !

Avatar
Crookie | 4 years ago
0 likes

I have done all this to my Cannondale Synapse 105 Carbon bought Dec 19.  Front 40-36 and rear 11-40 and it all works very well but I get a lot of chain slap and clunking from the bottom of the rear mech as though the chain is now too lose.  Do I need to shorten the chain from the original that fitted 50-34?  I think given the manufacture date on the bike that it has the Shadow mech and comparing the pictures I can see no difference that is obvious to me.  We have hills round Stroud and i am not getting any younger!

Avatar
CXR94Di2 replied to TimB34 | 5 years ago
1 like

TimB34 wrote:

Been meaning to mention this for a while.. 

Although the article says "The 11-40 cassette fits straight on the hub of my Prime RR-28 wheels in place of the 11-32", shimano 11-speed mtb cassettes are actually 1.8mm smaller than shimano 11-speed road cassettes. A lot of freehubs are short enough that you can screw the lockring tight enough and never notice, but the new mtb cassette will be nearly 2mm too far inboard.

I followed the same path from 11-32 to 11-40, but shifting was a bit noisy. I eventually worked out that a spacer was needed and added one. The cassette didn't seem any tighter on the freehub, but shifting noticeably improved.

 

The large sprocket MTB cassettes come with the spacer in the box to fit onto 11 speed hubs

Avatar
CXR94Di2 replied to Tones0000 | 5 years ago
0 likes

Tones0000 wrote:

I assume everyone has now seen the Shimano GRX series with 48/31 and 46/30 cranksets. The big question will be whether we can bodge an 11-40 or hopefully an 11-42 cassette onto the GRX long cage rear derailleurs which are officially rated for a maximum sprocket of 34T (36T on the 10 speed) and 47T capacity (like everyone has done on the recent road derailleurs).

 

Just use XT/XTR derailleurs and the new GRX crankset job donewink

Avatar
CXR94Di2 replied to Tones0000 | 5 years ago
0 likes

Tones0000 wrote:

Thinking about the Di2 route but coming from the other direction - rather than trying to squeeze a road rear derailleur around a MTB cassette: Does anyone have thoughts or experience running 46/30 chainrings on an Xt di2 front derailleur? 

A couple of possible issues:
Is the 16T jump too large for the MTB derailleur?
Is there a problem with the BB length (68 vs 73mm)?

Other issues?

Thanks

 

Yes, I built a full Di2 bike with initally a 40/28 chainset, I upped it to 44/28.  This was the maximum difference the XT Di2 front derailleur could manage.  I would expect 46/30 would fit.

I now run an XTR Di2 front with 48/36/26, work seemlessly.  Shimano say maximum chainring is 42t-haha

Avatar
CXR94Di2 replied to whizwith | 5 years ago
0 likes

whizwith wrote:

I had my LBS put on an XT M8000 11-40 on my Lynskey R260 R8050 Di2 setup . I was hoping to use an FSA 48/32 up front, but the frame can't do it with the Di2 wires in the BB. But the LBS said they could replace the 50 with a 46. So I have 46/34 up front, and 11-40 in the back. I need to go for more than a spin and shall report back but was looking for help - How should I adjust the synchro shifting? Is there a logic to the defaults Shimano uses for the 50/34 11-34 setup I had on there before? If someone can point me to a chart or something that explains the framework, I'd be grateful! Thank you

Its probably because the frame has a threaded English BB so the FSA BB not compatible

  If its a case of the bottom bracket compatibility with your frame you can use the latest Shimano groupset which is 48/32 46/30 GRX which is hollowtech.    

look here for guidance https://www.google.com/search?q=shimano+synchro+shift&oq=shimano+sy&aqs=...

I use bike calc https://www.bikecalc.com/gear_ratios to show me the gear inches or ratios, just depends which you prefer.  I use these ratios to decide when to allow synchro to jump up or down the  front derailleur.  Method is when changing to easier gearing you want the shift on the rear to drop down so many cogs, so its in the next easy ratio.  You dont want to cross chain if you can help it so change a cog early.

The 11-40 has gears : 11-13-15-17-19-21-24-27-31-35-40t

Whilst on the 46t chain ring when you get to gear 2 (35t cog) the next change will result in the syncro dropping down to the 34t chainring and setting the cassette gear to gear 4(27t)

If you look at the chart below Ive hightlighted in red and yellow the next gear points with ratios. 

Red is for changing to next easy gear    Yellow for changing up to next harder gear.  these are the points in which the front derailleur moves and the rear jumps up or down several teeth simultaneously.

hope that helps

Btw I have triple setup 48/36/26 with an 11-40 cass on Di2 with syncro

 

 

 

Pages

Latest Comments