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Should you go for a standard, a compact, a semi-compact, or something entirely different?

The chainset, called a crankset in some parts of the world, is the name given to the chainrings and the crank arms that turn them. Different chainsets make a big difference to the character of your bike and the way it feels when you ride.

Check out our Beginner’s Guide: Understanding Gears here.

Most road bikes come with a double chainset, meaning that you have two chainrings. The larger chainring gives you bigger, harder to turn gears that move you further per pedal revolution – so it's suitable for higher speeds – while the smaller chainring gives you gears that are easier to turn but move you a shorter distance per pedal revolution – so it's suitable for lower speeds, including riding uphill.

However, some bikes come with a triple chainset, meaning that you have three chainrings, and others use a single chainring matched to a wide-range cassette (the group of sprockets that sit at the centre of the back wheel).

Let’s go through the main road systems in turn.

Standard chainset

A standard chainset (a bit of a strange term these days) has a 53-tooth (or 52-tooth) outer chainring and a 39-tooth inner chainring. This used to be the default option for road bikes and it’s the choice of most racers in the majority of circumstances. Sometimes, though, pros will switch to larger chainrings for time trials or flat races like Paris-Roubaix.

campagnolo-chorus-standard.jpg

The big three groupset manufacturers, Shimano, Campagnolo and SRAM, offer standard chainsets in their higher level road groupsets aimed at pro riders and other racers/serious enthusiasts, but not in their lower end groupsets aimed at more casual riders.

Example bike Tifosi SS26

Compact chainset​

A compact chainset has a 50-tooth outer chainring and a 34-tooth inner chainring. This means that the gears are lower (easier to turn, but they’ll progress you a shorter distance per pedal revolution) than you get with a standard chainset (above) with the same cassette.

For more details on that, see How much difference does a new chainset make? (below).

Compact chainsets have become massively popular because they allow you to keep moving up steep hills, albeit sometimes quite slowly, and many people prefer to turn smaller gears at a higher cadence (the number of pedal revolutions per minute) because it puts less stress on the knees.

sramrival22crankset-compact.jpg

The flip side is that you might run out of gears on very fast descents. In other words, you won’t be able to turn the pedals fast enough to make any difference to your speed above a certain point.

Reflecting their popularity, the three largest groupset manufacturers offer compact chainsets across all of their road groupsets.

Example bike Wilier GTR Team Disc Endurance

Semi-compact chainset

A semi-compact chainset, sometimes called mid-compact or faux pro, has a 52-tooth outer chainring and a 36-tooth inner chainring.

This means that the biggest gears aren’t quite as big as those of a standard chainset but they’re not far off, and they’re larger than those of a compact.

The small gears aren’t quite as small as those of a compact chainset, but they’re smaller and easier to turn than those of a standard chainset.

Canyon Ultimate CF SLX - crank.jpgSemi-compact chainsets have become popular over the past few years because they offer something for most types of terrain. Many of the road bikes we review here at road.cc are now fitted with these.

The big three manufacturers offer semi-compact chainsets on all but entry-level road groupsets.

Example bike Giant TCR Advanced Pro 0

Sub-compact

Want lower gears? A sub-compact chainset is a double with rings smaller than the compact's 50/34 pairing. Usually they're 48/32 or 46/30, dropping the whole gear range a few percent to make those grinding climbs that little bit less painful.

FSA SL-K Adventure Chainset 2017.jpg

The gravel/adventure bike movement has been the main driver of sub-compact chainsets. Fat tyres and dirt tracks demand lower gears, especially if you’re carrying anything extra, like clothes and so on for an overnight stay.  

But we think they have a place for general riding too. As soon as you hit seriously hilly terrain, there's going to come a moment when you need the lowest gear you can get. You might have blown up, you might have hit a 20% grade or steeper. Options like FSA's Adventure series cranks, Sugino's OS cranks, or the Praxis Works 48/32 cranks give you a slightly lower gear range for those situations.

Example bike: Specialized Diverge Comp (the 2017 version gets a sub-compact chainset)

Triple chainset

A triple chainset is one with three chainrings. Shimano offers triple chainsets for its three cheaper road bike groupsets – Claris, Sora and Tiagra. In each case the chainrings are 50, 39, and 30-tooth. Campagnolo offers only Athena in a triple (52, 39 and 30-tooth chainrings) while SRAM doesn’t offer triple chainsets for its road groupsets, although it does for its Via 27 and 24 trekking ranges.

Shimano Tiagra triple.jpeg

You do get some very small gears with a triple chainset, but there’s a lot of duplication (different chainring/sprocket combinations giving the same, or virtually the same, gears) and most people find a double chainset with a wide-range cassette ample and more convenient to use.

That said, a triple can be a good idea, especially for something like a touring bike where you need those very small gears to climb while carrying a heavy load.

Swapping from a double to a triple, or the reverse, is quite an expensive process because you need to change other groupset components too.

Example bike: Cannondale Touring 2 adventure bike

Single chainset

Bikes with single chainrings are nothing new, of course – there are millions of them out there – but most aren’t particularly performance-orientated. Recently, though, SRAM has introduced single chainring versions of three of its road groupsets – Force, Rival and Apex – with wide-range cassettes.

sram rival 1 first ride7

SRAM says that these 1x (pronounced ‘one by’) groupsets are simpler because there’s no front mech or front shifter, there’s no chance of the chain rubbing on a non-existent front mech, and they’re quieter on rough surfaces.

SRAM also says that the interface between the chain and chainring is better because their specially designed chainrings have tall, square teeth edges that engage the chain earlier, and the traditional sharp and narrow tooth profile helps manage a deflected chain.

sram rival 1 first ride9

When we reviewed the SRAM Rival 1 groupset we said that it was simple and durable. It’s not a system that will appeal to everyone, but for a variety of applications such as gravel, adventure and cyclocross, it makes a lot of sense.

The 1x chainsets are available with a variety of different sized chainrings to suit the riding you do.

Example bike The Light Blue Robinson Rival 1x

How much difference does a new chainset make?

Say you have a typical 700c wheel fitted with a 25mm tyre, and you’re using an 11-28-tooth cassette. That’s a fairly common setup.

Specialized Diverge Comp Carbon - Turn Zayante BB30 Chainset.jpg

If you have a standard chainset, your smallest gear (39-tooth inner chainring x 28-tooth largest sprocket) is 36.7in. If that doesn’t mean much to you, check out our Beginner’s Guide: Understanding Gears for an explanation. Put another way, if you pedal at 80rpm, you’ll move at 8.7mph.

If you have a compact chainset, your smallest gear (34 x 28) is 32in, so quite a bit smaller than that of a standard chainset. That means it’s much easier to turn the cranks. If you pedal at 80rpm, you’ll move at 7.6mph, so quite a bit slower than when pedalling in the smallest gear of a standard chainset at the same cadence.

If you have a semi-compact chainset, your smallest gear (36 x 28) is 33.9in. If you pedal at 80rpm, you’ll move at 8.1mph.

At the other end of the speed scale, say the maximum cadence you can hold for a short period of time is 120rpm. If you pedal a standard chainset in your biggest gear (53 x 11), you’ll be able to pedal up to 45.4mph at this cadence.

Look 796 - chainset (1).jpg

Do the same thing with a compact chainset (50 x 11) and you’ll get to 42.8mph, and with a semi-compact (52 x 11) you’ll get to 44.5mph.

In short, a compact chainset will give you some small gears for keeping moving up steep hills while a standard chainset will allow you to keep the pressure on for longer on fast descents.

A semi-compact gives you some small gears, but not as small as a compact, and some big gears, but not as big as a standard chainset.

Changing chainrings

What if you feel the chainset you’re currently using isn't right for you and the riding you do?

Swapping chainrings is relatively straightforward in many cases (you'll need Allen keys, perhaps a Torx wrench or a chainring nut wrench tool), but you need to make sure you get new chainrings that are compatible with your chainset. Chainrings come with different bolt circle diameters (BCDs) and bolt spacings (higher level Shimano and Campagnolo chainsets come with unequal bolt spacings).

Shimano 11spd chainring.png

In many cases you can turn a standard chainset into a compact chainset simply by swapping the chainrings. You can take a 53-tooth outer chainring off a modern Shimano 105 chainset, for example, and replace it with a 50-tooth chainring because both chainrings use the same bolt circle diameter (BCD). This is also true of Dura-Ace, Ultegra and Tiagra.

This didn’t used to be the case. If you had a compact chainset with a 110mm BCD, you couldn’t fit larger Shimano chainrings with a 130mm BCD and SRAM, for example, still offers chainsets in both 130 BCD and 110 BCD options so the chainrings aren’t interchangeable.

The point is that you need to be careful to buy replacement chainrings that work with your chainset.

Don’t forget that if you change chainring size, you should adjust the position of your front derailleur accordingly, and alter the chain length too.

Mat has worked for loads of bike magazines over 20+ years, and been editor of 220 Triathlon and Cycling Plus. He's been road.cc technical editor for eight years, testing bikes, fettling the latest kit, and trying out the most up-to-the-minute clothing. We send him off around the world to get all the news from launches and shows too. He has won his category in Ironman UK 70.3 and finished on the podium in both marathons he has run. Mat is a Cambridge graduate who did a post-grad in magazine journalism, and he is a past winner of the Cycling Media Award for Specialist Online Writer.

89 comments

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JohnnyEnglish [31 posts] 1 year ago
1 like

In my view, the issue is more at the cassette end of the drivetrain than with the chainrings.

 

PpPete wrote:

 

Instead we're forced into fugly solutions like triples with the outer removed.

 

 

I'd be more than happy with the compact offering if only the manufacturers would give us a better choice of cassette ratios. 11 at the back is redundant for me and many I ride with. A cassette with 12 - 28 or 12-30 would still give a sufficient top speed, good range and close ratios.

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Crampy [154 posts] 1 year ago
0 likes
JohnnyEnglish wrote:

In my view, the issue is more at the cassette end of the drivetrain than with the chainrings.

 

PpPete wrote:

 

Instead we're forced into fugly solutions like triples with the outer removed.

 

 

I'd be more than happy with the compact offering if only the manufacturers would give us a better choice of cassette ratios. 11 at the back is redundant for me and many I ride with. A cassette with 12 - 28 or 12-30 would still give a sufficient top speed, good range and close ratios.

I have an Ambrosio 12-28 cassette on my CX bike, paired to a compact chainset. 

IIRC Campag also does Chorus cassettes in 12-27 - at least I think thats whats on my "race" bike - with a standard up front it is fine for pretty much everything except XTREME climbing. 

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Tom_in_MN [19 posts] 1 year ago
1 like

The types of cranks sets are really defined by their BCD (bolt circle diameter) which then defines the possible sizes of chainrings that can be used.  The BCD determines the smallest chainring that can be mounted.  The compact introduced a smaller 110mm BCD which allowed a 34t chainring as it's smallest ring on a double chainset.  You can still put regular 39/52, etc, chainrings on it if you want to, but on a standard 130mm BCD you can only have a 39t as the smallest.  Triples use two bolt circles to allow a very small chainring on the innermost 74mm BCD.  

So I would have reversed your discussion and started with BCD and gone from there.  If you want to change your rings the first question is, what BCD is your chainset.

I've found a compact (110 BCD) chainset with a 42/34 works very well, then I can run a small step cassette.  I don't need more than a 42:11 top end gearing, which gives 30mph at 100 rpm. And this avoids  the large 50/34 shift on the front that is just awkward to use. See

https://wickwerks.com/product-category/chainrings/cyclocross-chainrings/

for sub-compact chainrings designed to shift nicely.

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Barraob1 [33 posts] 1 year ago
0 likes
tritecommentbot wrote:

I have Ultegra 50/34 x 11 on my bike. Can I stick on a 52/36 Dura Ace crank? Or do I need to mess around with derailleurs and a new chain etc?

 

Feel like 52/34 would be my perfect chainset. Not sure if that can be made to work though.

You can I swapped out the inner ring on my ultegra and have no issues running 52/34

 

 

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CXR94Di2 [2658 posts] 1 year ago
0 likes

I run a mtb crankset with a 9 speed outer ring to make 44/28. I can climb mountains with a high cadence and average over 21mph on 80 mile runs, so most folk wont really need more. 

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Shades [483 posts] 1 year ago
0 likes

Got rid of a worn out MTB triple chainset on a commuter/tourer and replaced it with a Shimano SLX 38/28 chainrings with an 11-42 cassette (new derailleur as well).  Great for spinning up steep hills with just enough top-end for cruising on the flat.  Doubt a new bike would have been sold with that combo which is the joy of upgrading, rather than replacing the bike.

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torch_taylor [4 posts] 1 year ago
1 like

Hi,

 

Just swapped from a Compact + 11/32 to a Semi Compact + 11/34. Same bottom end and higher top end.

 

Perfect for all but the silliest of hills.

 

Ciao,

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Vejnemojnen [289 posts] 1 year ago
2 likes

IMHO for the leisure weekend warrior a 46 or 48t large chainring with cassette starting with 13t cog is perfectly sufficient.

 

With this obsession of 11t starter cog and 50-52t chainring people spend too much time with suboptimal oblique chainline and even cadence imitating bullet time effect (ie.: slow motion).

 

back in the nineties, the weekend-hobbyst group, RSX featured 46-36 chainset with 13-26 cassette.

 

With 11 speed, a 13-30 cassette would provide everything one can ask for if not racing: fine increments at the bottom, yet wide enough gearing for serious gradients... 

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CXR94Di2 [2658 posts] 1 year ago
3 likes

At 90rpm  

46-11 combination will attain 29mph

50-11........................................32mph

53-11........................................34mph

 

How many people can sustain 29mph on the flat?

 

Thats why I use 44T chainring, when conditions are optimal, strong tailwind and -1% slope I can attain 27-30mph and hold it- just.   

 

This is on a flat 10 mile section with a tiny tailwind on the above gearing, I was working quite hard

Im in the top 8% for the segment, the vast majority of people dont need 50 or 53 t chainrings

 

 

 

Avatar
Vejnemojnen [289 posts] 1 year ago
1 like
CXR94Di2 wrote:

At 90rpm  

46-11 combination will attain 29mph

50-11........................................32mph

53-11........................................34mph

 

How many people can sustain 29mph on the flat?

 

Thats why I use 44T chainring, when conditions are optimal, strong tailwind and -1% slope I can attain 27-30mph and hold it- just.   

 

Thank you for the numbers. I wish more people would see the truth. Though I've written different ratios, I was considering cassettes with 12 or 13t initial cog.

 

The speeds you are quoting are more than enough for the average Joe.

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CXR94Di2 [2658 posts] 10 months ago
2 likes

A further experiment to my quest for the perfect gearing.  I swapped my 44/28 chainset for a triple XT Deore 48/36/26, bought a triple XTR Di2 derailleur.  This has further improved the gearing range to now cover both ends. It has allowed me to use one less cog whilst on the 26t chainring(mountains) and when powering along slight declines use less cadence with the 48t chainring.

  •    rpm    80       85      90       95      100     105     110
  • 26x40   4.07    4.32   4.58   4.83     5.09    5.34    5.59 ---  (min gearing mountains)

  • 26x32   5.07    5.39   5.70    6.02    6.34   6.65    6.97

  • 36x12  18.78  19.95  21.12  22.30  23.47 24.65  25.82

  • 48x11  27.29   29.00 30.70  32.41  34.11 35.82  37.52

 

I spend most of my time in the 36t chainring around 90-95rpm  The chainline is further improved with much less cross-chaining.  The Di2 programmed to syncro shift at the relevant points. 

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slappop [73 posts] 7 months ago
0 likes
Quote:

SRAM says that these 1x (pronounced ‘one by’) 

That fact that it constantly has to be emphasized how the name of this product is prounounced must be a constant, pustulent sore to the SRAM marketing department.

I'm afraid that I couldn't possibly countenance buying a safety-critical item of equipment from a company that shows such shoddy attention-to-detail.

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cyclisto [412 posts] 7 months ago
4 likes

I see here a lot of comments about the efforts of people trying to achieve short gearing while I see that the majority of entry level road bikes and even worse gravel bikes have compact 34-50 cranksets and I ask myself whether the bicycle and drivetrain manufacturers are blind.

I use a triple trekking 26-36-48 that is must if you had to face my not that athletic built, 2-digit slopes in my daily commutes and occasional trips with panniers. My needs sound like the most of entry level cyclists and yet the viable gearing options are very few.

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bikezero [65 posts] 7 months ago
0 likes

A run-down about which speed chainsets work with which speed groupsets would be very helpful for me to read. Seems for example if your bike has an 8 speed groupset (still not at all uncommon on entry level road bikes), your options for chainwheel upgrades are very limited. Is a double 9 speed chainset ok to put with a double 8 speed group? I've been told that with a double 8 speed groupset a 10 speed would have issues and 11 speed a no-go with major issues. For 8 and 9 speed chainsets, it doesn't seem there are a lot of options to chose from. With speeds having increased a lot of over time looks like there are no high spec (lightweight) 8 and 9 speed chainsets made by any manufacturers nowadays though maybe I have missed something.

What about a 9 speed group? (again hugely common today on semi-pro road bikes). Is a 10 speed chainset fine to pair with them, an 11 speed chainset..?

Should one consider a rule of thumb to be that a chainset should not be more than 1 speed higher than the your groupset's speed?

Any links to info or articles about this subject would be appreciated. Thanks.

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CXR94Di2 [2658 posts] 7 months ago
0 likes

As far as I Know 9/10/11 are compatible with chains.  There are slight width differences in chains but not so much to affect shifting.  I have used 9 speed chainrings with 11 speed cass and used 10 speed chain.  It worked fine

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ChrisB200SX [1039 posts] 7 months ago
0 likes

AbsoluteBlack now offer 2 sub-compact oval chainring combinations, this could be perfect for many. 

I'm also a fan of 14-28 ultegra 11-speed cassettes. Although I would consider 11-23 on a sub-compact oval chainring... weight and aero reduction!

Avatar
maviczap [370 posts] 7 months ago
0 likes
CXR94Di2 wrote:

As far as I Know 9/10/11 are compatible with chains.  There are slight width differences in chains but not so much to affect shifting.  I have used 9 speed chainrings with 11 speed cass and used 10 speed chain.  It worked fine

Didn't think 10 speed chains would work with an 11 speed cassette, and I had tried before, maybe it was the quick link I was using.

But I'll bow to your experience and see if one of my 10 speed chains will work with my 11 speed set up. Makes sense as there's bugger all difference between 10 & 11.

Would be handy as 10 speed chains are cheaper than 11's!

I've used 10 speed chainsets on my 11 speed set up for a long while, and I'm using a 10 speed front mech and shifter on my steel winter bike, but with 11 speed rear. That also works fine.

Praxis Works make a 48/32 sub compact chainring set on a 110bcd, which means you don't need to buy a specific sub compact chainset. The inner mounts on the outer, as it's the BCD that dictates the smallest size inner chainring possible.

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CXR94Di2 [2658 posts] 7 months ago
0 likes

Those looking for something sub compact double chainset,  the FSA Omega Adventurer range has 48/32 46/30 also 50/34.

  I would be inclined to buy the 48/32 and swap out the inner ring for a 30.   BCD is 120/90 for rings

Avatar
iso2000 [116 posts] 7 months ago
0 likes
CXR94Di2 wrote:

Those looking for something sub compact double chainset,  the FSA Omega Adventurer range has 48/32 46/30 also 50/34.

  I would be inclined to buy the 48/32 and swap out the inner ring for a 30.   BCD is 120/90 for rings

Unfortunately no one seems to make a sub compact chainset that will fit my Trek with its BB90 bottom bracket. I could fit Absolute Black oval rings but even then I'm not sure I can lower the front mech enough. Time for a new frame?  

 

Avatar
CXR94Di2 [2658 posts] 7 months ago
0 likes
iso2000 wrote:
CXR94Di2 wrote:

Those looking for something sub compact double chainset,  the FSA Omega Adventurer range has 48/32 46/30 also 50/34.

  I would be inclined to buy the 48/32 and swap out the inner ring for a 30.   BCD is 120/90 for rings

Unfortunately no one seems to make a sub compact chainset that will fit my Trek with its BB90 bottom bracket. I could fit Absolute Black oval rings but even then I'm not sure I can lower the front mech enough. Time for a new frame?  

 

Sounds like a new more versatile frame essential . Wide tyre capability, disc brakes, relaxed geometry, threaded bottom bracket and no to brazed derailleurs mounts-clamp only.

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srchar [1481 posts] 7 months ago
0 likes
iso2000 wrote:

Unfortunately no one seems to make a sub compact chainset that will fit my Trek with its BB90 bottom bracket. I could fit Absolute Black oval rings but even then I'm not sure I can lower the front mech enough. Time for a new frame?  

Unfortunately, yes, it sounds like it - with a threaded BB (I know they're getting rarer...)

Avatar
S3dbw [2 posts] 7 months ago
0 likes
iso2000 wrote:
CXR94Di2 wrote:

Those looking for something sub compact double chainset,  the FSA Omega Adventurer range has 48/32 46/30 also 50/34.

  I would be inclined to buy the 48/32 and swap out the inner ring for a 30.   BCD is 120/90 for rings

Unfortunately no one seems to make a sub compact chainset that will fit my Trek with its BB90 bottom bracket. I could fit Absolute Black oval rings but even then I'm not sure I can lower the front mech enough. Time for a new frame?  

 

Not necessarily! I currently have a couple of Trek Domane's both running with absoluteblack 48/32 chainrings. I actually had to raise the FD slightly when I fitted them as the max width of the ovalised section of the 48 ring is slightly larger than the standard 50 shimano ring the Treks came with. The one thing you do have to note with absolute black rings is that they sit about a couple of mm closer to the frame than the shimano rings, which meant ,in my case, that initailly the lower limit onthe FD would not go in far enough. This was easily cured with a 1mm space on the crank, however it is somethingto be aware of if you plan on going this route. Brilliant set of chain rings, would never go back to round rings.

 

Avatar
CXR94Di2 [2658 posts] 7 months ago
1 like
srchar wrote:
iso2000 wrote:

Unfortunately no one seems to make a sub compact chainset that will fit my Trek with its BB90 bottom bracket. I could fit Absolute Black oval rings but even then I'm not sure I can lower the front mech enough. Time for a new frame?  

Unfortunately, yes, it sounds like it - with a threaded BB (I know they're getting rarer...)

 

If you're talking about threaded BB frames in general, there seems to be more manufacturer s using English BBs.  They are so much better, easy to replace and cheap

 

Avatar
iso2000 [116 posts] 7 months ago
0 likes
S3dbw wrote:
iso2000 wrote:
CXR94Di2 wrote:

Those looking for something sub compact double chainset,  the FSA Omega Adventurer range has 48/32 46/30 also 50/34.

  I would be inclined to buy the 48/32 and swap out the inner ring for a 30.   BCD is 120/90 for rings

Unfortunately no one seems to make a sub compact chainset that will fit my Trek with its BB90 bottom bracket. I could fit Absolute Black oval rings but even then I'm not sure I can lower the front mech enough. Time for a new frame?  

 

Not necessarily! I currently have a couple of Trek Domane's both running with absoluteblack 48/32 chainrings. I actually had to raise the FD slightly when I fitted them as the max width of the ovalised section of the 48 ring is slightly larger than the standard 50 shimano ring the Treks came with. The one thing you do have to note with absolute black rings is that they sit about a couple of mm closer to the frame than the shimano rings, which meant ,in my case, that initailly the lower limit onthe FD would not go in far enough. This was easily cured with a 1mm space on the crank, however it is somethingto be aware of if you plan on going this route. Brilliant set of chain rings, would never go back to round rings.

 

Thanks that's reassuring. Can you expand on the 1mm spacer please. Where exactly is this put?

 

Avatar
iso2000 [116 posts] 7 months ago
0 likes
CXR94Di2 wrote:
srchar wrote:
iso2000 wrote:

Unfortunately no one seems to make a sub compact chainset that will fit my Trek with its BB90 bottom bracket. I could fit Absolute Black oval rings but even then I'm not sure I can lower the front mech enough. Time for a new frame?  

Unfortunately, yes, it sounds like it - with a threaded BB (I know they're getting rarer...)

If you're talking about threaded BB frames in general, there seems to be more manufacturer s using English BBs.  They are so much better, easy to replace and cheap

Don't think I could back to a steel frame. What bottom brackets do titanium manufacturers use?

Avatar
maviczap [370 posts] 7 months ago
0 likes
ChrisB200SX wrote:

AbsoluteBlack now offer 2 sub-compact oval chainring combinations, this could be perfect for many. 

I'm also a fan of 14-28 ultegra 11-speed cassettes. Although I would consider 11-23 on a sub-compact oval chainring... weight and aero reduction!

Thank you, thank you, thank you. I Googled  Absolute Black subcompact and found they do a 46/30 or a 48/32 combination that fits 4 arm Shimano 110bcd cranks. 

So I can get the low gearing I want, but keep my road cranks and bsa bottom bracket. Plus they look trick & I can keep them just for my Alpine trips and swap them out for normal 52/36 or 50/34

Avatar
S3dbw [2 posts] 7 months ago
0 likes
iso2000 wrote:
S3dbw wrote:
iso2000 wrote:
CXR94Di2 wrote:

Those looking for something sub compact double chainset,  the FSA Omega Adventurer range has 48/32 46/30 also 50/34.

  I would be inclined to buy the 48/32 and swap out the inner ring for a 30.   BCD is 120/90 for rings

Unfortunately no one seems to make a sub compact chainset that will fit my Trek with its BB90 bottom bracket. I could fit Absolute Black oval rings but even then I'm not sure I can lower the front mech enough. Time for a new frame?  

 

Not necessarily! I currently have a couple of Trek Domane's both running with absoluteblack 48/32 chainrings. I actually had to raise the FD slightly when I fitted them as the max width of the ovalised section of the 48 ring is slightly larger than the standard 50 shimano ring the Treks came with. The one thing you do have to note with absolute black rings is that they sit about a couple of mm closer to the frame than the shimano rings, which meant ,in my case, that initailly the lower limit onthe FD would not go in far enough. This was easily cured with a 1mm space on the crank, however it is somethingto be aware of if you plan on going this route. Brilliant set of chain rings, would never go back to round rings.

 

Thanks that's reassuring. Can you expand on the 1mm spacer please. Where exactly is this put?

 

Place the spacer (if required) on the drive side of your crank, this has the effect of pushing the crank rings out slightly and thus allowing proper adjustment on the lower limit on the FD

Avatar
CXR94Di2 [2658 posts] 7 months ago
0 likes
iso2000 wrote:
CXR94Di2 wrote:
srchar wrote:
iso2000 wrote:

Unfortunately no one seems to make a sub compact chainset that will fit my Trek with its BB90 bottom bracket. I could fit Absolute Black oval rings but even then I'm not sure I can lower the front mech enough. Time for a new frame?  

Unfortunately, yes, it sounds like it - with a threaded BB (I know they're getting rarer...)

If you're talking about threaded BB frames in general, there seems to be more manufacturer s using English BBs.  They are so much better, easy to replace and cheap

Don't think I could back to a steel frame. What bottom brackets do titanium manufacturers use?

 

My Kinesis Tripster V2 Ti uses threaded BB.  The J ack Laverack Ti bike is threaded.  When I first looked at their frame you could specify pressfit or threaded. Planet X Ti are threaded.   

Avatar
BlindFreddy [19 posts] 1 month ago
0 likes

Have been pleased by my ultra-low gearing experiment, namely:

   11-42 Shimano cassette;

   M8000 SGS rear derailleur (47t capacity);

   Sugino OX 28/44 sub-compact chainset;

   M7000 105 front derailleur; and

   Tanpan cable converter at the front near the 105 rear shifter/brake (away from the road and contamination).

Works a treat with a 600% spread from 18 gear inches to 108. I spend most of my time in the large cog but when it gets steep and the load heavy, I drop down to the small chaniring and breathe a sigh of relief.

It's on a Specialized Diverge which has short chainstays so I cannot use the two smallest cogs while in the small chain ring. Not a practrical problem because after the first few low gears it makes sense to be in the large chainring's lowest or second lowest gears of 28.3 gear inches or 32.1 gear inches, respectively.

The Sugino OX chainset comes in a range of chainring sizes with the smallest being 30/44, to get the 28t granny I bought their standard 9 speed 28t chainring and chamfered the outer edges of the chainring bolt holes to get proper clearance from the frame - you simply copy the chamfers on the 30t ring. Works a treat as the pins and ramps are on the 44t chainring. The Sugino chainset has performed well.

Can recommend.

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