How to Choose Your Chainrings

When we received another shipment of René Herse cranks recently, we built up and filled our pre-orders first. Some are shown above. All the cranks shown have different setups, except two. (Can you spot the two identical ones?) There are a dozen different chainring combinations in the photo above, yet they represent only a small fraction of the possible chainring choices with our new cranks. We currently offer more than 100 different useful crank configurations to customize the crank to your power output and pedal style.

You can compare that to most makers: Not counting track cranks, Shimano offers seven chainring combinations for their Dura-Ace cranks. Ultegra is available in four combinations, including a single triple. Campagnolo offers just three combinations for their Record cranks. None of the big makers offer 48-32, 44-28 or 46-36-24, combinations that are very useful for many riders.

Our René Herse cranks can be set up in even more chainring combinations, but our 100 combinations count only those that make sense and offer excellent shifting performance. Here is how to figure out an ideal chainring choice for you. (This post is excerpted from a more detailed article on gearing in the Summer 2012 issue of Bicycle Quarterly.)

One big rule is that the difference between adjacent chainrings ideally should not be larger than 16 teeth. You can use a larger difference – I once tested a classic René Herse bicycle with a 52-26 double – but your shifting will not be ideal. For example, a 48-32 (16 tooth difference) will shift fine with most front derailleurs, but a 48-30 (18 tooth difference) may require trimming of the front derailleur after each front shift. A large chainring difference also can result in the chain rubbing on the large chainring when you ride in the small chainring in the front and on one of the smaller cogs in the rear.

With this in mind, you can freely spec your favorite chainring combination. When I select my gearing, I think of three gears:

  • Base gear: This is the gear I mostly use on flat roads when spinning along.
  • High gear: This is the largest gear that I use when I am sprinting for a city limit sign with friends, or riding with a powerful tailwind.
  • Low gear: This is the smallest gear I need on the roads I usually ride.

In addition to covering the range from low to high gear, a good gear selection will do the following:

  • Put the base gear in the middle of the rear freewheel/cassette, so that I can adjust to changes in speed and terrain with a simple shift or two in the rear.
  • Provide small enough steps between gears, so that I can continue pedaling seamlessly.

I don’t worry about duplicate gears, if they fall in the range where I ride frequently. In fact, some overlap is not just OK, it’s desirable.

The worst gearing I have ever ridden was that bike I mentioned above with the 52-26 chainrings. It had a 14-28 freewheel. On paper, this might look ideal: a huge gear range, and only one duplicate gear. On the road, it was far from perfect: In the big ring, the gearing was just a tad too large for slight uphills, while in the small ring, the gears were too small for the flats. As a result, I was shifting all the time, not only the front, but also almost all the way across the rear. This really broke my rhythm.

If I were riding that bike all the time, I’d simply add a third chainring (which is relatively easy with René Herse cranks)*. Adding a 44-tooth ring would not have changed the gear range, and added five duplicate gears. On paper, that would be useless, but on the road, those would be the gears I would use 90% of the time! With the 44-tooth chainring, my base gear would be in the middle of the freewheel, and if the road tilts up or down a bit, I’d just need a simple shift on the rear to be in the right gear again. The 50-tooth chainring might be useful for super-fast rides, while the 26-tooth ring would get me up any hill.

Double or Triple?
The decision comes down to the gear range you need and which gears you ride most of the time. If your “base gear” is close to your “high gear,” then you can accommodate both on the same chainring. That means that you can use a double.

If your base gear is right in the middle between your “high” and “low” gears, then a double would put you between the two rings most of the time. Get a triple instead!

Alternatively, if you don’t like the wider tread (Q factor) of a triple, think about reducing your high gear. You don’t give up much – pedaling on steep downhills is slower than tucking in the aero tuck anyhow – and you may be able to use a double.

Choosing your gearing well will increase the enjoyment of your ride. Click here to see the chainring choices that are available for the René Herse cranks. For a more detail and examples of chainring choices, check out the Summer 2012 issue of Bicycle Quarterly.

* To convert a double René Herse crank to a triple, you need an extra chainring, longer chainring bolts, and (usually) a longer bottom bracket spindle.

About Jan Heine, Editor, Bicycle Quarterly

I love cycling and bicycles, especially those that take us off the beaten path. I edit Bicycle Quarterly magazine, and occasionally write for other publications. One of our companies, Bicycle Quarterly Press publishes cycling books, while Compass Bicycles Ltd. makes and distributes high-quality bicycle components for real-world riders.
This entry was posted in Rene Herse cranks, Testing and Tech. Bookmark the permalink.

23 Responses to How to Choose Your Chainrings

  1. marmotte27 says:

    I’d say the two identical ones are those just to the right of the middle with the crankarms sticking out almost horizontally to the left.

  2. bryanwieyes says:

    Here’s the key question (for me) – are the RH chainrings (and cranks?) compatible with modern Campy Record derailleurs and 11speed chains? (Thus with modern brifter levers?)

    I switched my cross bike to Campy “cross” and record compact double. (Spendy) But the shifting is stunning, even compared to my very good (but 10 year old) campy triples. And the ratios are fine for me for cross (where of course by definition you sometimes get off and run.) But for my winter road bike, why not, say, a 30-46. A 46×12 is MORE than big enough for my winter use. A 30×29 is very handy. The constraint is that I hugely prefer the campy brifters and the shifting of record derailleours.

    (Obviously this same question applies more generally to SRAM/Shimano/FSA?/whoever else)

    [And there is a special place in the afterlife reserved for the people who sell carbon cranks for high ground impact appliactions like cross... Jeez folks, aluminum and steel are both really advanced technologies.....]

    • When we designed the cranks, we decided to make them compatible with 10-speed only. That way, they still work great with anything from five-speed chains and drivetrains upward. 11-speed really seems silly, even though I realize it is becoming the norm. The compromise in chainring life was not worth it for us. In the future, we may offer specific 11-speed chainrings, but that would double our (already very substantial) chainring inventory.

      If you use a 10-speed drivetrain, the René Herse cranks/SKF bottom bracket combination will drop right in. You may need to adjust your front derailleur slightly, but there are none of the other issues of many boutique cranks, such as the chain hitting the end of the crank in the largest gears, the front derailleur touching the crankarm, etc.

      My friend Ryan has been riding all year on his Herse cranks with a Dura-Ace 10-speed drivetrain, and Hahn has logged quite a few miles on the cranks with SRAM double-tap. Of course, if you use fewer than 10 cogs in the back, it’ll work great as well. My Herse has a five-speed freewheel which I use with an 8-speed chain, and it works great.

    • nellegreen says:

      The best rando distance combo for me is: front 42/28 with rear 13/28 using 8 speed cassettes. 42/19 is my Base Gear. 42/13 is fast enough to stay with the group as i can spin at high cadence. For high elevations i found the 27 inch development of the 28/28 insufficient, and walked a lot above 8,500 ft. I would have preferred the 25.2 development of a 28/30. http://sheldonbrown.com/gears/

  3. RodneyAB says:

    With your use of 7/8 speed chain, and a 0.4mm spacer under the small chainring, did you use longer than standard chainring bolts?
    Perhaps a 9 speed chain will work fine with the standard chainring space?, the increased space does interest me.

    • Before we get into details, you can run the Rene Herse cranks with any chain from 5-speed to 10-speed without modifications.

      I put in the 0.4 mm spacers only because I wanted to see what would happen, since I started with a 5-speed chain. To be honest, it’s hard to notice the difference, but it doesn’t seem to hurt, either. We may offer the spacers in the future for others who are interested. (I just filed them from a sheet of aluminum after drilling/filing the three holes.) For a moment, I was concerned that the narrower 7-speed chain that I eventually used might drop into the space between the chainrings, but so far, no problems at all. The difference in chainring spacing really isn’t that great – 5-speed was only 0.4 mm larger than 10-speed. I used standard chainring bolts.

  4. AndrewGills says:

    Thank you for the information. While I’ve been riding all my life, I have only recently started paying attention to my running gear etc. I always like it when my bikes have a double-up because it allows me to continue riding at the same cadence while preparing for either uphill or downhill.

    My 1997 Trek OCLV 5200 is currently at the bike shop having a new 10sp Shimano Tiagra groupset installed. I can collect it this morning. I didn’t pay attention to the gear ratios that I’m getting because I was just happy to be able to get a groupset I could afford. But next time I replace the chainrings / crankset I’ll come back to this post and pay more attention.

  5. For most of my bikes, a 46×34 (110bcd cranks) plus a 11-32 cassette is perfectly adequate. For my camper, I add a granny and swap a 36 for the 34, since it becomes my base gear.

  6. Garth says:

    top left and bottom right big gears are 44t. small gears show barely a third tooth between the triangular sections of the large gear. Prize? ; )

  7. John Duval says:

    What really bothers me about the big brands is not the chainring combos they offer, but that the BCD is so large that you can’t put useful gears on them regardless of availability. I was able to find a 42t outer ring for my SRAM compact double, but the smallest inside ring is 33t.

    Unfortunately, at 6’6″, cranks any shorter than 180mm kill my legs. Also, I have always had chronic chain rub on taper type spindles, but none at all with the new fat tubular systems.

    • I agree on the silly large bolt-circle diameters – one of the main reasons we decided to offer the Herse cranks again.

      The chain rub seems to be more the result of out-of-true chainrings than of the spindle-crank interface. A square taper is a very strong interface that does not move, and the spindle itself is much stiffer than other parts of the frame.

      • doug says:

        I think I read on your blog or in your magazine about lightly greasing square taper spindles to get a better mounted crank. I tried it, and found that I no longer had issues with non-straight running chainrings. Suddenly they all always ran perfectly parallel to the derailleur. It solved an annoying problem I’d been tolerating for years and years.

  8. Matthew J says:

    Useful article. Thank you.

    One point or question as the case may be. Is TA not considered a major crank manufacturer? The Carmina while less attractive than your Herse has a very broad configuration range.

  9. Shu-Sin says:

    Bottom-right crank and second from top-left are identical double-ring cranks.

  10. Base with high: interesting rule of thumb for choosing a double or triple. I would add that the concept of “gear ranges” is also useful if your rides vary greatly by load or by terrain. I set up my Fargo all purpose bike with my cruising gear on the big (46) t ring and in the middle of the cassette (18 or 10 t depending on 27″ Kojak or 29″ Big Apple wheelsets) for rolling pavement and small loads. I use the 36 when carrying 20 + loads and for steep dirt. (I hardly ever use the 24, but since the chainstay design will not allow a 36 to get any closer to the frame, I just leave it in place for the occasional perfect storm combo of load + long, steep hill, or deep sand.)

    I run 7 cogs (15-29, 16-34) on the outside of 8/9/10 speed freehubs so both the 46 and the 36 can be used with all 7 cogs; this gives me a range of mid 80s to about 40″ on the 46 and from 65″ to the low 30s on the 36. The 24 works fine with the two or three innermost cogs.

    Actually, 46/38/24 and 15 or 16-36 would be even better and I may just swap out middle ring and large cog to get a slightly higher “low” range while maintaining the same bottom gears.

  11. Willem says:

    There is a Carmina in 180 mm, and you can get a 29t smallest ring for an ultracompact double.
    Willem

  12. RickH says:

    Gear range combos are always a contentious issue depending on your riding terrain and of course your own personal abilities.
    One thing I cannot find mentioned is the compatibility between chainrings whereby the chain falls fluently into the next chainring. One bike I have has the chain sitting on the peak of the teeth until it releases from the other chainring. In this instance, one tooth difference either way would have a much smoother change without the precarious worry about the chain falling off.

    • On most chainring combinations, there are 2-4 spots where the chain smoothly can span from one ring to the other (where the distance between the teeth is a multiple of the length of a chain link). I have not yet encountered a combination like you describe, where there are no such spots, but it’s conceivable that some exist. You might try rotate one of the rings a bit to get a different alignment of the chainrings in relation to each other.

Comments are closed.