How To Choose Your Chainrings + Cassette – GCN's Guide To Selecting Road Bike Gear Ratios

How To Choose Your Chainrings + Cassette – GCN's Guide To Selecting Road Bike Gear Ratios

Having the right gear ratios on your bike will make a huge difference to your riding experience. Here’s a quick guide to how they work.
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Your gear ratios are defined by the size of your chainrings and the ratios offered by your cassette. Your tyre width also affects this to a certain extent, but by far the biggest influence us exerted by the chainrings and cassette.

On a road bike you have two choices of chainset. Standard, which is commonly 53×39 and compact, commonly 50×34. Cassettes generally offer gears in the range of 11-25 or 11-28.

In this video, Dan Lloyd explains how gear ratios are calculated and how you can use that knowledge to your benefit – don’t forget to SHARE!

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  1. S G on November 7, 2019 at 4:24 pm

    12-36 has good range of high & low gears…

    12,13,15,17 good high end minus 14t cog
    28,32,36 good low end for hills

    To upgrade or not?

    I was debating on whether or not to spend $4600 + $460 tax for new 2017/18 Paris Roubaix Expert + ~$2000 more for clipless pedals, Garmin, etc… The 2017/18 Paris Roubaix Expert is truly a beautiful bike, with a lot of new technology…

    However, I decided to keep that money and upgraded my 2008 Paris Roubaix Expert Triplet instead, which already has clipless & Garmin and only had to add 12-36 cassette, RD hanger & new chain : $133 vs $5000-$7000 for new bike and accessories…

    I suspect there’s no paved roads I won’t be able to climb with 36t in rear and 24t in front, bike only weighs 18-20 lbs, plus I still have fast gears for down hills and flats…

    Chain Rings Ultegra:
    52-39-30 before
    52-39-24 now

    11-28: 11-12-13-14-15-17-19-21-24-28 Ultegra CS6700 original

    12-30: 12-13-14-15-17-19-21-24-27-30 Ultegra CS6700 – now

    12-36: 12-13-##-15-17-19-22-25-28-32-36 SRAM PG-1070 going to

    Parts Added / Swapped In

    Shimano 24T… : Chain Ring Cog
    Shimano CN-6701 : Ultegra chain
    Shimano CS-6700 : Ultegra 12-30
    Shimano M772 : XT RD
    SO Roadlink RD hanger for 12-36

    If for some reason 36 is overkill I’ll go to 12-32 as majority of my riding occurs between 13,14,15,17.

    I suspect I’ll miss 14 cog when going to 12-36…

    List of upgrades ( see 1st, 2nd 3rd )

    11-28: 11-12-13-14-15-17-19-21-24-28 1st
    12-30: 12-13-14-15-17-19-21-24-27-30 2nd
    12-32: 12-13-14-15-17-19-22-25-28-32
    12-36: 12-13-##-15-17-19-22-25-28-32-36 3rd

  2. I/O on November 7, 2019 at 4:25 pm

    And why not combine an ultegra 52-36 and a Deore 11-42 cassette? According to Shimano they’re fully compatible down to the chain. You get the speed and the climbing power.

  3. Big D on November 7, 2019 at 4:25 pm

    I have a campy short cage with 12-25 cassette and 52 34 chain ring. Struggling climbing up hills. What cassette can I get for climbing with the campy brand. Do I need to change the campy short cage derailer as well. HELP!!

  4. World's Best Pedal on November 7, 2019 at 4:25 pm

    I developed an oscillating pedal that is very efficient and it is the World’s Simplest design. Use a conventional bike, just remove it’s cranks, spindle and chainwheel then assemble this invented mechanism . The conventional bike frame’s bottom bracket will be the housing of this invention….. @

    Here are the reasons why you should invest for this project @t

    Inventor: Genaro Francis Tabag

  5. Connor Price on November 7, 2019 at 4:27 pm

    Watching in 2019!

  6. greimalkin on November 7, 2019 at 4:27 pm

    Can you do a video of how the gears work? I haven’t found a good video. Like so far I’ve gathered that it has a lot to do with the ratio of the gear that’s in your pedal compared to the gear in the back because then there are more rotations in the back of the wheel per rotation of where your feet are on the pedals. Anyway I think I kind of get it but there isn’t actually a video that explains it well

  7. Reid Wagner on November 7, 2019 at 4:30 pm

    I run 11-32 with 50/34. Been running that for years. I’m an older rider and still do on ok on most climbs but slower due to age I’m sure. Love the 32 in the rear.

  8. Cycling Dinamics on November 7, 2019 at 4:34 pm

    I have a 50/34 chainrings and I want to change my chainrings to a 52-36. Can I make that change with the same crankset?

  9. I lick the insides of microwave popcorn packages on November 7, 2019 at 4:34 pm

    I’m a mountain biker, used to technical climbs with gradients that do not exist anywhere on roads and for that I run by most people’s standards a maybe a bit narrow 12-36 x 36/26 gearing. After getting a road bike (on which I focus on touring, climbing and building my base), I have to say a 50/34 compact with an 11-28 cassette has become my go-to standard which I will not abandon. Still able to get really high speeds on the descents and I can tackle any, and I mean absolutely any climb out there without destroying my knees or getting too trashed to enjoy the rest of the ride.
    Even if I was oriented towards more of a flat riding, I’d still run the compact, to be honest. Not necessarily because of the 36T chainring, but because a 53T chainring gives me quite a few gears which I never use on flat. I gave the 53/39 a fair chance but after switching to compact, I saw only positives with no drawbacks.

  10. Leonid Denisenko on November 7, 2019 at 4:36 pm

    What would happen if I put shimano 105 road group set on a fat bike?

  11. Munther G-mail on November 7, 2019 at 4:36 pm

    what is 10 speed chain…!! and how can i tell which one is mine when it all it’s written is "Narrow Z"….??

  12. MrHolm on November 7, 2019 at 4:37 pm

    im a junior and i had too ride with 16 teeths at the back and 50 at the front which leaves me spinning for most of the time

  13. Sam Jackson on November 7, 2019 at 4:39 pm

    12sp campy is the future

  14. Jon Prevost on November 7, 2019 at 4:39 pm

    2006 Specialized Allez Comp Triple is my ride and the better my fitness the more I enjoy having the triple. As a Clydesdale my main concern while riding alone is to have a durable ride. The triple lets me decrease the cross-chaining and because the more I ride, the better my gear selection technique and the kicker… my cadence increases. All of these reasons make me enjoy the small ring up the hills and then snap up to the big ring if I have energy to spare. It’s fun passing everybody with my triple. Has there ever been a good study for large riders with regards to triple cranks?

  15. Frank on November 7, 2019 at 4:39 pm

    Love all your videos, keep up the good work

  16. Jose Ricardo Perez on November 7, 2019 at 4:39 pm

    Always awesome man thanks.

  17. Propolizei on November 7, 2019 at 4:40 pm

    Am I going to get a significant higher speed on flat road, changing my 12-25 with 11-32 cassette? (Or any other with 11 lower ring, just because of that one highest speed) Right now I am riding a triple 50-39-30 chainset with 12-25 cassette. Thanks for any advice.

  18. WillN2Go1 on November 7, 2019 at 4:40 pm

    I’m looking at MTBs to replace my old bike. But here’s the problem. I have a 26" wheel bike and I’ll probably want a 27.5 or a 29" wheel bike, so what does that do to gear ratios? (It’s like 4,5 and 6 percent differences. Just enough to be confusing, but not small enough to not matter.)
    The online calculators are helpful, but they ask for tire size, and then they give you every number for every combination of gears. TMI! I don’t know enough to understand anything more than my lowest combination for climbing and my highest gear combo for speed. So I’ll only look at the top and the bottom. All I need is to be able to quickly convert gear ratios and wheel sizes to numbers I can compare. Gear ratio x wheel size is all that’s needed.
    My current 26" Fisher has a low gear ratio (smallest Front Gear / largest rear gear) of .88, I want to do better than this (meaning a lower number). But what would this be on a 27.5 and 29? well 26 x .88 =22.9 (this is a conversion number) An equivalent gear ratio on a 27.5 wheel would be 22.9/27.5 = .83, and 22.9/29= .79 I struggle on some of my climbs, so I want a bike that will climb better than my old Fisher, so for a 26" that would be better than .88, for a 27.5 better than .83 and for a 29 better than .79. Now all I have to do is count sprockets and do a little math. (Comparing what you know with the bike in front of you… this is a lot easier and more understandable then the huge charts)
    For the top end same thing; my bike’s fastest gear combination (Front/back) is 3.43 , some new bikes are 4.00 and some of the single front sprockets are only 2.73. (But the wheels are bigger…..) So 26 x 3.43= 89, 27.5 x 2.73 = 75, 29 x 2.73= 79. Both are much slower than what I have now. However a 4.00 x 27.5 = 110 and 29= 116. much faster than what I have now. The 1×10 bike that tops out at only 72 and 79 might be okay on trails only, it’s going to be slow on pavement to and from the trail.
    To compare speeds Wheel size x (Front/Rear gears) x Cadence / 336= mph ( change to /210 for KPH)

  19. Chris Chou on November 7, 2019 at 4:42 pm

    might be a stupid question, but whats with the green tape on the frame? or is that part of the design

  20. nathan bowen on November 7, 2019 at 4:43 pm

    Now I know why I’m flying by people on $2000 bikes up most relaxed climbs and being blown away on anything slightly steep. My old 80s Norco has a 14-28 cassette and a 52-42 chainring. I think Im going to change it out for a 52-36.

  21. NicGyver on November 7, 2019 at 4:46 pm


  22. Cyclone Fruitbat on November 7, 2019 at 4:48 pm

    I’m 11, and live in quite a hilly area, but I have a standard (53/39). I rarely use the big ring.

  23. Sloane on November 7, 2019 at 4:48 pm

    Thanks for all the great videos and advice GCN!

  24. jimnyfuchs on November 7, 2019 at 4:49 pm

    50-34 crank with 11-36 here, thanks to Sora-Alivio-Interchangeability. I use it on my gravelish commuter (grommuter) to tackle even steeper hills with ease.

  25. Philip Clare on November 7, 2019 at 4:49 pm

    Can’t believe you clamped the frame!!!

  26. Carson Stephens on November 7, 2019 at 4:50 pm

    52/36 and 11-34t. Got some crazy hills but some great flat and downhills

  27. Vicky Vonstein on November 7, 2019 at 4:53 pm

    Can I use a 39/53 with a 12/30 using a 6700 short cage? Has anyone done this? I know the Shimano document says 28 teeth.
    Would I have to add a chain link or two?

  28. Jay Tan on November 7, 2019 at 4:55 pm

    Quick question. Im planning to upgrade my drivetrain from Claris to 105. can I still use my Claris crank on an 11-speed flywheel? thanks

  29. To To on November 7, 2019 at 4:55 pm

    I wish Shimano would also offer a 48/32 crank set. For me that would be better (on a cross bike). Now I am thinking about changing my 11-28 cassette against a 12-30. That would do the same right?

  30. G on November 7, 2019 at 4:55 pm

    Why do you need so many gears (e.g. 11x cogs, 22 speed), considering at least a third or even 1/2 of all the gear ratios are duplicated when alternating the chain ring?

    This duplication can be minimized by having a longer derailleur (bigger capacity) to account for a wider chaining differences say 58t / 24t with 12-29t cassette. Doesn’t exist right now, but no reason not to.

    Also, why not use 62t chainring x 13t? As you will gain much finer "increment when reaching top gears" on flat road e.g. 18 > 17 > 16 > 15 > 14 > 13t from 3.44 to 4.77 ratio that spread across 6x gears.

    Meanwhile, if using 52t x 11t only gives you "5x gears equivalent spread" (from 3.47 to 4.73) NOT 6x e.g. 15 > 14> 13> 12> 11.

    SRAM 1x eagle 10-50t cassette, deliberately exaggerated it gear ratio to reflect the math of ratio by having their mid cassette with" fine" ratio increment and "broad" ratio between cogs near highest and lowest speed.

    Their setup is really for MTB ratio, not for road use, but it possible to have 1×12 with fine increment cogs at top speed.

  31. Woodcock Johnson on November 7, 2019 at 4:56 pm

    Hang on – is that GCN with a bike clamped by the top tube? Credibility just took a hit.

  32. sonomama82 on November 7, 2019 at 4:57 pm

    I have an old Raleigh Elan that currently has a bent crank and I want to upgrade it. I currently have a 7 speed cassette however most modern cranks aren’t made to work with a 7 speed cassette. Does that actually matter? I am not a pro. I just had my crank wobbling while I am riding.

  33. Christopher Jenkins on November 7, 2019 at 5:01 pm

    Most popular is 50/34 on front (compact) and 11-28 on the back. But I always run 11-32 on the back. If you are on a ride where you don’t know where you are or try a different route and suddenly find the gradient above 20% or you have blown or get cramp and need to get over some testing hills, you always have that last gear to let you spin away. There’s nothing worse going to go down a gear and find you have none left. Going up 20% on a 28 starts to get to the point you are grinding up.

  34. Danfuerth Gillis on November 7, 2019 at 5:02 pm

    Lol now with Cassettes and Chain Rings you can modify the Gearing to anything you wish example 11,12,15,16,18, 23, 34 for a 7 gear cassette.

  35. Neil Reeby on November 7, 2019 at 5:04 pm

    I’ve a kinesis crosslight cycle cross bike, fitted with 105 5800 group set and looking at fitting an 11-40 cassette by using a road link, having seen a few videos of this done the chain ends being to slack when going small small and over tight when running big big, so was wondering if it would be practical to run a 36-50 front ring instead of 34-50?

  36. George Gkiokas on November 7, 2019 at 5:04 pm

    So a mountain bike with 11×42 cassette and 26-36 chainring is it fast or no? I am looking for a fast mtb can somebody answer to me please?

  37. Worldwide Ghosts on November 7, 2019 at 5:05 pm

    Good stuff!

  38. Zak Swan on November 7, 2019 at 5:05 pm

    Why is Simon not presenting this video

  39. Ken Noble on November 7, 2019 at 5:06 pm

    I run a compact in the front and assemble my own rear cassette. On a series of flat rides, I paid attention to what rear gear I was riding in. This I made my center ring. I went smaller one tooth down from there until I ran out of rings. I did this because I noticed when I accelerated I usually came to a cog that jumped two teeth which I couldn’t pull. The single tooth was easier to pull. Going up, I only went one additional cog twice and then advanced to my climbing gears, topping out at twenty eight. It is too bad cassettes come with fixed gear ratios. The cyclist should determine which cog combinations is best for them.

  40. Reuben Cheang on November 7, 2019 at 5:06 pm

    I am now seeing a 55/42 crankset. Would this then be faster than the "standard" 53/39?
    And I would assume the former would not be so "helpful" in a climb but would fly faster on a flat.

  41. tigeroscarfan on November 7, 2019 at 5:08 pm

    i still find this very confusing, i remember people used to say it will be like 2nd nature to you from experience, i use my bike on the trainer at the moment as im new to cycling and never rode a bike as a kid, just got into to it as an adult and i have fell in the bushes lots of times trying to ride a bike lol i don’t think im rode safe yet. you know where you have big chainring with the smallest cassette would that be like your best setting for flat surface and then if it gets to a slope move across the cassette’s then when in the middle shift down to a smaller chainring to avoid cross chaining. im just trying to get the general idea here lol im a beginner. if you go up a 17% steep hill i bet you’d need smallest chainring with largest cassette to be able to pedal well.

  42. Benjamin Lewis on November 7, 2019 at 5:14 pm


  43. S H on November 7, 2019 at 5:14 pm

    Even now this is outdated.. as someone who rides 1500 miles a year, a compact is always best. it will happily take me to 50 mph (try 40 mph by the time you hit 50mph gear ratios don’t matter (its a case of holding on and surviving)). I’d be lost without 34-28 as a decent cyclist. Don’t spec a bike like the pros used to…

  44. henrybikeman on November 7, 2019 at 5:14 pm

    You refer only momentarily to gear inches, as if it was boring and trivial.
    In fact it’s absolutely CRUCIAL and not hard to understand.
    A single number from say 20 to about 125 for very low to very high. Applies to all wheel sizes too!
    All this "52 x 11" stuff is nonsense. If you prefer you can use rollout distance but in Anglophone countries inches is most widely understood.

  45. Manuel Abella on November 7, 2019 at 5:15 pm

    i want to convert my bike to 1×9 setup to go around the city is it ok to use 42t chainring on 12-36 casette?

  46. Requiredfields2 on November 7, 2019 at 5:17 pm

    I don’t think you’re giving compact set ups enough credit. 50/11 is a bigger gear than 53/12 so there is very little compromise at the top end. However, and more importantly, at the bottom end you have 2 easier gears than 39/28 (34/25 and 34/28). It’s a better fit for pretty much everyone who rides on anything other than flat terrain at all times.

  47. Alonso Martii on November 7, 2019 at 5:18 pm

    I live in a place that everything is flat and used 52/39-11/28.
    I use every single speed and I get most of my money worth, unlike 50/34-11-32 that 34-32,34-28, and 34-25 was not used ever.

  48. ROD RODRIGUEZ on November 7, 2019 at 5:20 pm

    Endurance Bike comes mostly now with 50/34 & 11/32.

  49. Dan Uber on November 7, 2019 at 5:21 pm

    Logan has right

  50. vidio hd on November 14, 2019 at 3:34 am

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