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Out of the box, gravel bike gears are too high. Here's how to sort them out

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?

Acknowledged by the Telegraph as a leading cycling journalist, John Stevenson 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 editor Tony Farelly, 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 and these days he lives in Cambridge where the lack of hills is more than made up for by the headwinds.

106 comments

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reippuert [122 posts] 1 year ago
2 likes

have SRAM X0 type 2 (clutch) rear derailure. Enables me to run a std Cmapy Compact 50/34 with up to an 11/40 casette. Will work with SRAM's std 2x11 brifters out of the box.

 

however i cheated and prefer Ergo's so im running my old Chorus 10 speed Ergo's so i have modified the castte by replacing the spaceres with 10 speed spacers, dumped the 11t and 13t and added an Ultegra 10 speed 13t end cog. 50/34-13/40 is a decent gravel gearing for +40mm 700c tyres.

 

Im still missing the 14t, 16t cogs though for a tight higend. When said i really love the even jumps from 21-24-27-31-35-40 on the low end when climbing.

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alanmc [8 posts] 1 year ago
0 likes

Another option for sub-compact chainrings on a Shimano chainset :

https://absoluteblack.cc/oval-road-chainrings-30-46-and-32-48-for-110-4bcd/

 

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John Stevenson [450 posts] 1 year ago
1 like

reippuert wrote:

however i cheated and prefer Ergo's so im running my old Chorus 10 speed Ergo's so i have modified the castte by replacing the spaceres with 10 speed spacers, dumped the 11t and 13t and added an Ultegra 10 speed 13t end cog. 50/34-13/40 is a decent gravel gearing for +40mm 700c tyres.

I'd want a lower bottom gear, but then I am fat and unfit (and using an old pic in my site bio to fake otherwise).

But if we were handing out awards for gear tinkering, that mixture of parts from all three major drivetrain manufacturers would surely win you a gold star!  1

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John Stevenson [450 posts] 1 year ago
2 likes

alanmc wrote:

Another option for sub-compact chainrings on a Shimano chainset :

https://absoluteblack.cc/oval-road-chainrings-30-46-and-32-48-for-110-4bcd/

Elliptical rings!

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jollygoodvelo [1879 posts] 1 year ago
3 likes

Enjoyable read.  We sometimes forget that bikes aren't all that complicated. The first time I stripped a bike down to its frame was a weird experience, one moment it was just a pile of bits and a little while later it was a bike again.  They're not F1 cars or living things where everything is unique, they're just a collection of bits - levers, cogs and stuff - and those bits are frequently interchangeable. 

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alanmc [8 posts] 1 year ago
2 likes

C'mon Shimano - even  on road, never mind gravel or touring, us mere mortals would really be better served by  48/32 or even 46/30 "sub"-compacts, and sensible cassette options - 13 or even 14 to 32/34 ??  

 

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michophull [160 posts] 1 year ago
0 likes

Hmm. I'd personally be inclined to try an old school MTB triple chainset, say 24-34-44.

If your front shifter won't cope with three rings then I'd dump the 44. 

You can keep your existing cassette, rear mech, and shifters that way.

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billymansell [75 posts] 1 year ago
2 likes
gonedownhill wrote:

Slightly off topic, but has anyone ever converted a ss Shimano derailleur to a GS by swapping the cage plates? You can buy 6800 plates from sjs cycles, lot cheaper than a new derailleur.

Yes I've done this on several derailleurs, converting both 6700 and 6800 SS derailleurs with 6800 GS plates and inserting a reverse facing allen head bolt in place of the b screw to give a 34T capacity.

Have also run one of these with a Wolftooth Roadlink to give space for up to a 40T sprocket.

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alexb [208 posts] 1 year ago
3 likes

I spent a happy few hours on Sunday riding NCN21 from around Crystal Palace down to Eridge, on my audax bike running full-length mudguards and road tyres (700x28c) with a 30 speed Campag triple set up.

Despite what Sustrans will have you believe, this route involves quite a lot of off-road trails, some quite narrow and loose. I was amazed at what I could clear with 30x29t as my lowest gear on essentialy slick (Vittoria Randonneur at the rear Michelin Dynamic at the front) tyres.

I'd thoroughly recommend taking your unsuitable bikes off road from time to time. I had a blast haging the back end out on loose descents, but the whole 1x, massive rear sprockets, enouromous derailleur cages fad at the moment drives me mad. Most of the time the answer is a triple chainset and shifters. Yes, it's a bit of extra weight, but I'd guess that my extra chainring weighs a lot less than the massive steel sprockets used to replace it and it allows me to use pretty cheap components elsewhere.

 

 

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BehindTheBikesheds [3322 posts] 1 year ago
1 like
alanmc wrote:

C'mon Shimano - even  on road, never mind gravel or touring, us mere mortals would really be better served by  48/32 or even 46/30 "sub"-compacts, and sensible cassette options - 13 or even 14 to 32/34 ??  

Shimano have been behind the game in this for a long while, they've followed the path of 1x and whilst that will suit some it's not actually what the majority want certainly not for road riding and I'd contend that 1x on all but very specific types of MTBing is not all that brilliant either.

They've shot themselves in the foot with regards to the more touring and leisure riders and I'd even say audax too by stopping up their triple groups to Tiagra (4700 currently), even then it's very expensive and not that common, you certainly wouldn't find it in stock in a shop on the high street and online retailers are few and far between. Sure 'we' have all had to adapt because the big three have all ignored touring/audax for the most part and we make do with bodges like mix and matching cassettes or buying third party chainsets or simply be forced to have something that doesn't really suit your needs. 

They should have gone down the compact triple route years ago following up on the old RSX compact road chainset fom the 90s, they really fucked up IMHO by continuing with the 'road' triple and insisting on 52(or 50)/39/30 but further by not offering triple STIs in 11 speed not higher than Tiagra in 10 speed. You can still buy new 6700/5700 triple STIs but they're circa £170 and very few and far between and they're holding their price for mint used ones because they're so spartan.

I'm using a 50/39/24 with an 11-28, that gives me a 23" low and I don't need to worry about the jumps between the ratios which is something people (including reviewers) don't want to talk about when transitioning both up and downhill particularly under load. When your're betwix and between and trying to find your cadence sweetspot that's when wide range cassettes get found out and the jumps are so wide that that transition can be disrupting to your flow and can unbalance you if putting lots of effort through the pedals going down a much bigger gear than you want or find that the jump up means your cadence is much slower so you're having to dig to get back up to optimal revs, this is just as important touring as it is racing IMHO and is why I won't ever want to go to a really wide cassette.

Don't get me wrong, I like 11 speed, it makes 12-30 so much easier and I've said in the past that a 12 or 13 speed cassette in say 12-32 with a 50/28 would be just about the sweetspot for me. I can actually get 50/28 easily enough using my old Stronglight 86mm and the rings work fine with 10/11 speed chains but the problem is that 12 and upwards means a whole new frame/wheels.

I think a 12/13/14 speed hub gear with a double chainset might well be a way to go to get that really wide range without massive cassettes/really long drailleurs and chainlines and jumps that are at extreme ends.

A racing internal gear hub reduces wheel dish (so stronger/lighter compared to a wide dished wheel, no rear derailleur, perfect chainline all the time, more aerodynamic, not having to spread the frames even wider and with electronic/wireless shifting already a thing for gear hubs with some tweeks regarding weight (like not building them to last 40-60k miles) they could end up being a solution for the wider and lower gear ratio. Unless one of the big three take the jump and go back to making triples (ok SRAM never made them) with sensible gearing options, but it simply won't happen.

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Bmblbzzz [347 posts] 1 year ago
0 likes

Yean, ^^ riding "unsuitable bikes" in unsuitable places should be done. Occasionally! A bit of "comedy off-roading". But maybe not as a regular thing. 

Triples, yes. But they're becoming rare as OME, which means that if you're altering a stock bike – as opposed to building up from scratch – you're almost certainly going to have to get hold of a triple shifter, which ain't cheap. 

Oh, and mudguards are good too!

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colouryum [3 posts] 1 year ago
2 likes
roadmanshaq wrote:

A very interesting read!

 

Are the SRAM 1x set up gravel bikes generally geared OK? I am on the lookout for a "gravel bike" to use for touring in countries with roads and trails even ropier than ours, and like the idea of a 1x on the ease of use and reliability front. For example the PX Full Monty maxes out at 42 42 which I thought would be good enough for pretty much anything bar really serious climbing. 

 

I recently changed my SRAM setup. I bought the bike with a SRAM Force 1 which was running 42 chainring and 11-32 cassette. This served me well til I started doing some bigger rides with some hard gradients - 16% + climbs. 

I am now running the SRAM Apex 1 mech with 11-42 so have that golden 1:1 ratio and it's doing the job - I'm very rarely going into the 42 unless it gets really hard but it's working perfectly. I'm yet to do a fully laden ride with all my bike packing stuff on so might be fighting a bit for some more range but just need to get a bit stronger. I can always get a smaller chainring for a big tour.

Don't get put off by the purists. They ride what they know and don't like change. That's good for them. I like the simplicity of less moving parts and less maintenance. 

 

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CXR94Di2 [2732 posts] 1 year ago
3 likes

I run XT Di2 on my bike, but now upgraded the front derailleur to Triple XTR. I have a crankset of 48/36/26. and either run 11-32 for general riding or 11-40 Cass for alpine climbs

All setup with 'Syncro Shift' so there is no cross chaining. In fact the drive line is superior to a double crankset

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John Stevenson [450 posts] 1 year ago
0 likes

michophull wrote:

Hmm. I'd personally be inclined to try an old school MTB triple chainset, say 24-34-44.

If your front shifter won't cope with three rings then I'd dump the 44. 

You can keep your existing cassette, rear mech, and shifters that way.

Not going to work well on any bike with a braze-on front derailleur mount.

Mismatch between curves of 34 ring and a front derailleur designed for a 50-53 means it's unlikely to work well at all even if you can get the derailleur low enough.

34/11 top gear is going to be too low for many people. At 90rpm it yields about 22mph.

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recurs [35 posts] 1 year ago
0 likes
alanmc wrote:

C'mon Shimano - even  on road, never mind gravel or touring, us mere mortals would really be better served by  48/32 or even 46/30 "sub"-compacts, and sensible cassette options - 13 or even 14 to 32/34 ??  

 

 

I’m quite surprised by Shimano’s apparent unawareness of these massive gaps in their groupsets. It wasn’t an issue up to 9 speed, so no one complained. With all the different cable pulls now, it’s up to Wolf Tooth, Microshift, FSA, et al to make Shimano’s stuff work in a whole bunch of real world scenarios. 

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darrenleroy [336 posts] 1 year ago
0 likes
John Stevenson wrote:
darrenleroy wrote:

Interesting feature. Could we have more of these please? Perhaps one on understanding gear inches for idiots.

I had a stab at that here: https://road.cc/content/feature/171317-beginners-guide-understanding-gears.

If that doesn't do the job, come back to me here and I'll have another go.

darrenleroy wrote:

I posted a while ago about needing to increase the range before heading out to the Pyrenees next month. I have a 10 speed 11-25 cassette on the rear with a compact chainset. I have an old Record rear derailleur that won't extend as low as 32. I don't  understand gear inches and the online tables mean create more confusion as I don't have an engineering degree.
What size chainset should I replace mine with to get the equivalent of a 34-32 (or lower)? 

Assuming you have a compact chainset, then you have a 37-inch low gear. The 34/32 you'd like is 29 inches.

As far as I can find out, your Record rear derailleur will shift up to a 29-tooth largest sprocket, but only the medium-cage version will be happy taking up all the chain slack generated by an 11-29 cassette and a 50/34 chainset. If that's what you have, then you're good to go. That gives you a 32-inch low, which is some 16% lower. The gaps on your 11-25 cassette will be quite small, so that will feel like it's one or two gears lower.

If you want a lower gear still, you're going to need a subcompact like the FSA mentioned in this article. That would give you a 30/29 low, which is 28 inches. In terms of how that'll feel, it's two or three gears lower than what you currently have.

 

Many thanks.

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macrophotofly [333 posts] 1 year ago
0 likes
gonedownhill wrote:

Slightly off topic, but has anyone ever converted a ss Shimano derailleur to a GS by swapping the cage plates? You can buy 6800 plates from sjs cycles, lot cheaper than a new derailleur.

Yes, did it on the Di2 Ultegra RD. Works perfectly and I now use it with a 11-32

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Shades [504 posts] 1 year ago
0 likes

My hybrid/tourer MTB triple chainset (Deore I think) needed replacing.  I wanted to simplify things and the mechanic came up with a Shimano SLX set-up; 38/28 with 11-42 cassette.  Good low gears for hills and enough to cruise along the flat.  Not a set-up that I've seen on a bike in an LBS.

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D-Squared [16 posts] 1 year ago
0 likes

My gravel bike has a 40 chain ring and 10-42 cassette. That covers everything I encounter on the roads it is intended for. 40x42 gives me 25 gear inches that will take me up most hills - it takes me up a couple of regular 18% climbs seated (which I need to be to keep weight on the back wheel in the loose stuff). And the 40x10 is all I need for a fast ride on the tarmac on the way to my dirt destinations. Only drawback (and it applies to the setup described in this article too) is that my gravel bike inevitably tempts me to push the boundaries into places where I really should be on the MTB

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maviczap [389 posts] 1 year ago
0 likes
John Stevenson wrote:
alanmc wrote:

Another option for sub-compact chainrings on a Shimano chainset :

https://absoluteblack.cc/oval-road-chainrings-30-46-and-32-48-for-110-4bcd/

Elliptical rings!

 

Praxis works do round chainrings 46/32 110bcd so works with Shimano compact chainsets

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John Stevenson [450 posts] 1 year ago
0 likes

maviczap wrote:

Praxis works do round chainrings 46/32 110bcd so works with Shimano compact chainsets

The Praxis 32-tooth inner ring only works with Praxis cranks that have the ends of the spider milled to make room for the chain.

https://road.cc/content/review/219120-praxis-works-alba-m30-4832-chainset

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CXR94Di2 [2732 posts] 1 year ago
1 like
Shades wrote:

My hybrid/tourer MTB triple chainset (Deore I think) needed replacing.  I wanted to simplify things and the mechanic came up with a Shimano SLX set-up; 38/28 with 11-42 cassette.  Good low gears for hills and enough to cruise along the flat.  Not a set-up that I've seen on a bike in an LBS.

I was running a 40/28 XT crankset but found I had too high a cadence on the flats or slight decline to keep up with guys on compact crankset, so I upgraded the outer ring to 44t which was much better, almost perfect setup for me. But I then wanted even more speed and reduced cadence, so I upgraded my setup to triple with 48t outer chainring. (see above)

I now have a bike (Kinesis Tripster V2) which I can use for fast flat riding 22+mph and with even lower gearing than my MTB double crankset for alpine climbs, the chain line is much improved with less chain deflection, being Di2 I can program the shift sequence to chain alignment optimal.

My range in gear inches. is 17" to 115"

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Turaco [2 posts] 1 year ago
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Nice piece. Sadly it only arrived just after I went down the XT derailleur, 11-42 cassette, tanpan shifter pull converter route….
Given the chance again, I’d go the route you have described, though I’d be tempted to opt for the Ultegra RD-RX805-GS derailleur with the mtb style clutch. The XT derailleur route works fine, but it isn’t really practical if you want to keep converting between mountain bike and road cassettes. 
One issue I found that will apply to the 11-40 cassette with a 105 derailleur is that Shimano 11speed mountain bike cassettes have a slightly smaller pitch than their 11speed road cassettes. The whole cassette is 1.85 mm narrower. This meant I needed to put in a spacer in to hold the cassette tight its hub.
 

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rogermerriman [162 posts] 1 year ago
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D-Squared wrote:

My gravel bike has a 40 chain ring and 10-42 cassette. That covers everything I encounter on the roads it is intended for. 40x42 gives me 25 gear inches that will take me up most hills - it takes me up a couple of regular 18% climbs seated (which I need to be to keep weight on the back wheel in the loose stuff). And the 40x10 is all I need for a fast ride on the tarmac on the way to my dirt destinations. Only drawback (and it applies to the setup described in this article too) is that my gravel bike inevitably tempts me to push the boundaries into places where I really should be on the MTB

 

Ah not the only one, my gravel bike and the CX before it remind me of the MTB's I grew up on, oddly I find its the tyres that fail, nomally sidewall rips! I have been trying not to push so hard!

 

with that in mind the 32-32 has been fine in this dry weather! be a touch over geared come winter!

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Argos74 [517 posts] 1 year ago
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Y'all are doing the work of Satan.  Carry on.

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twelvestocks [5 posts] 1 year ago
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I usually refer to what the article refers to as capacity as the max tooth of the derailleur. What I normally consider capacity relates to the amount of chain that the derailluer can wrap, given the difference in distance around the smallest ring and sprocket combination compared to the biggest.

I've found that while Shimano are conservative in their quoting of max tooth (as correctly stated in the article), the capacity they quote is accurate. This can mean that if you put a bigger cassette on and then set your chain length to be able to access the big-big combination, you can then be unable to get to some of the smaller sprockets when on the small chainring. The chain may be slack running the risk of coming off and/or slapping on the chainstays. 

I've found this using an RX9000 derailleur on a Specialized Roubaix with a 50-34 compact chainset. I fitted an 11-36 cassette (only 2 teeth bigger than recommended). Quoted capacity for this derailleur is 39 teeth. My setup needs 50-34 + 36-11 = 41 teeth. I find that I can't use the small-small combination. This is a cross chained combination to be avoided anyway and so I just live with it. 

I'd quite like to find a way to create or buy a 48-34 or 46-32 chainset and not have this small problem, but I've yet to work out how to do it. 

 

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John Stevenson [450 posts] 1 year ago
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In the small-small combination on my set up there's still a small amount of tension in the rear derailleur arm. Not, I admit, a huge amount, but enough that I don't worry about accidentally using the 30/11 combination.

twelvestocks wrote:

I'd quite like to find a way to create or buy a 48-34 or 46-32 chainset and not have this small problem, but I've yet to work out how to do it. 

 

FSA make rings available separately, so you could buy any of their Adventure 46/30 chainsets and a 32-tooth ring, and swap the 30 for the 32.
https://shop.fullspeedahead.com/en/type/cranksets

You could get one of Praxis Works' 48/32 chainsets and replace the 48 with a 46.
https://www.upgradebikes.co.uk/Catalogue/Praxis-Works/Praxis-Works-Range

You can assemble just about any combination you can imagine from the various rings and spiders available from Specialities TA
https://www.chickencyclekit.co.uk/brand.php?brands=16

 

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John Stevenson [450 posts] 1 year ago
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Argos74 wrote:

Y'all are doing the work of Satan.  Carry on.

Satan is my co-pilot.

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vanderlay [53 posts] 1 year ago
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Hi John

Great article. I’m running 46/30 FSA modular front and 11-34 Ultegra 11 speed rear at the mo. I’d like to go to 36 or 40 at the rear but isn’t derailleur capacity an issue for chain length? Do you need to avoid small/small or big/big completely? I worry that I’ll forget and end up with a mangled rear mech and wheel!

Cheers

Chris

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John Stevenson [450 posts] 1 year ago
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vanderlay wrote:

Great article. I’m running 46/30 FSA modular front and 11-34 Ultegra 11 speed rear at the mo. I’d like to go to 36 or 40 at the rear but isn’t derailleur capacity an issue for chain length? Do you need to avoid small/small or big/big completely? I worry that I’ll forget and end up with a mangled rear mech and wheel!

Thanks!

In the small-small combination on my set up there's still a small amount of tension in the rear derailleur arm. Not, I admit, a huge amount, but enough that I don't worry about accidentally using the 30/11 combination.

I was very careful to set it up so that the large/large combination works, because I've seen what happens when it doesn't. I was riding the course at the mountain bike world championships in 1990 when I met a member of the Canadian team who'd shifted into big/big and his transmission had completely jammed, and he had no idea what to do. 

I went into Bicycle Repair Man mode and helped out by opening his brakes and rear quick release and whacking the rear wheel good and hard to get it out of the dropout.

He was running a short-arm rear mech, a really common hack at the time to save a few grams and get a bit more ground clearance, but whoever installed it had been a bit frugal with the chain. One more inner-outer link pair would have averted disaster.

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