A higher/bigger gear will not make you go faster

Going faster isn't quite that simple...
Going faster isn’t quite that simple…

I recently spent a fair amount of time on the phone with someone convinced the only way he’s going to go faster on his bike is with a bigger sprocket. He’s currently got a 50 tooth up front, 11 tooth in the back. (Before going any further, the basics of gearing are that the larger the front chainring, the higher the gear. For the rear, the smaller it is, the higher.) To put that in perspective, he’s already got a higher gear than the legendary Eddy Merckx had, probably the best bike racer who ever lived. And he was very, very fast!

A “normal” bike comes with a high gear that’s probably a 50 tooth chainring up front, combined with a 12 tooth sprocket in back. With a 700 by 25c tire (normal for a road bike), you would be going 26.2 mph at a leisurely cadence (number of times your crank is going around each minute) of 80rpm. A mere mortal cannot sustain that high a speed, regardless of gearing. A highly-trained professional cyclist can maintain 30 mph on a bicycle designed specifically for time trials (for about an hour, racing against the clock, without other people around), but for the rest of us, 22-24 mph is the best we can hope for over a distance of greater than a mile or so. Seriously.

24 mph (with that 50/12 combination) is only 73 rotations of the pedals per minute, well within the range attainable by virtually anybody, regardless of physical strength (73 rotations of the crank per minute that is; 24 mph is another thing entirely). Even at 60 rotations per minute, you’re still doing 20 miles per hour, and of the many thousands of my customers, a relatively small number can probably maintain that speed for any distance.

Which chainring will make you go faster, the larger one or the smaller one (which came stock on your bike)? Answer: The smaller one.
Will you go faster if you replace the stock chainring on your bike, like the 50t one shown here, with a larger chainring, like the 56t behind it? 99% of the time the answer is no, you will likely go slower.

That example is for a 50 tooth front, 12 tooth rear sprocket. The gentleman in question already had an 11 tooth rear, so at 60 rpm he’s going 21.5 mph. To get to 30 mph, he’s only pedaling at 83 rpm. But the laws of physics won’t allow him to get to 30 mph, unless he has a strong tailwind or is descending. And if descending, he’s going to go even faster if he tucks in a bit and gets a bit aerodynamic; pedaling will actually slow him down, due to turbulence.

But why not have that ultra-high-gear anyways? What’s the harm? The human body is simply not made to produce optimal power at very low pedaling rotation speeds (rpm). You need more horsepower than you have to push a really high gear at low RPMs. A tandem, where you have the horsepower of two people pedaling, can often make use of higher gears. A normal person, even an abnormally-strong person, cannot.

Let’s talk first-person here. Me. I’m known to be a high-gear sort of guy. People make fun of me because I use higher gears than most others that I ride with. How high? My flat-land cadence is typically around 80 RPMs (it should be closer to 90). If I’m feeling good, I can do 21 mph using a 50 tooth chainring up front, with a 15 tooth rear. If I shift to a higher gear, I will not go faster! I will simply pedal more slowly and my speed will gradually drop as my legs become sluggish from trying to push too hard on the pedals.

What about descending Skyline from Kings Mtn to Sky L’onda, where you can get to 40 miles per hour? My highest gear, a 50-tooth front/11-tooth rear, would have me pedaling at 112 RPMs to get to that speed. And yes, I can pedal that fast, if I want to. But I will go faster if I don’t pedal! Pedaling creates choppy air that slows you down. The only exception to this is if you’re drafting (following closely behind) a large truck, but even then you’ll probably get sucked along behind it without having to pedal.

So how high a high gear do you need? For most, a 50 tooth front, 13 tooth rear would manage everything needed. There might be a very rare time something taller would be useful, but not too often. At 90 RPMs, you’d be going 27.2 mph. Nearly every road bike (and most hybrids) have a higher gear than that though, typically with a 12-tooth in the back. That would give nearly 30 mph at 90 RPMs. You might never have occasion to use a higher gear.

And if you’ve already got an 11-tooth in back (as many bikes come with stock), don’t expect a receptive audience at your local bike shop as you’re trying to explain your need for a bigger gear so you can go faster. Don’t take my word for it. Read what Kevin Metcalfe, a top racer (if 10,000 people read this post, there might, maybe, be a single person faster than him), has to say about gearing. And a discussion in a triathlon group on the same subject.

Thanks for listening-  Mike Jacoubowsky, former racer, present-day bicycle retailer, long-time cyclist and more patient than I should be entertaining people who think they need higher gears.

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10 thoughts on “A higher/bigger gear will not make you go faster

  1. Mike, Next time someone wants a bigger gear, tell them that Kevin Metcalfe just set the national 45+ 25mi TT record with a time of 49:29 (30.3mph), on a 50×39 compact crank. Here’s a quote from a slowtwitch post:

    “I did it on a compact, 50×39. Averaged 101 rpm, 309 Watts, 172 bpm. Max speed was 55kph at 105 rpm for a few seconds which implies that I briefly got into my 50×12. Mostly I was in a 13 and 14. I had an 11 but never used it. My main point here is that next time you think you “need a 55″ or whatever that maybe you don’t.”

    1. Lanier: Yep, read that piece. Really excellent! It’s like wow, somebody gets it! Not to mention that the guy is just extraordinary beyond belief, pulling that off at almost “my” age. Sure puts me in my place!!! –Mike-

  2. Exactly! So why do bikes come with 50×11 or 52×11 as top gears?
    I have a 52/39/30 triple with an 11-25 cassette (10 speed). Would trade that cassette for a 12-25 in a heartbeat, 16 tooth cog so much more useful than the 11!

  3. You didn’t mention sprinting. I do the alviso crit noon ride on Tuesdays and Thursdays. Riders often get to around 40 mph in the finishing sprint. I tend to have a high cadence, and have nver felt that I need bigger gears in a sprint or otherwise; however, one of the riders there believes he gets spun out in the sprints and needs a bigger gear than his 50×11.

    1. Don’t give people any ideas! It’s probably bad enough that I even show a photo with a 56t chainring, giving people the notion that hey, they’re out there, I want one! –Mike–

  4. OK, so with all the talk I’m still a little confused. Let’s make it simple: I’m considering a Cannondale CAAD 10 5 105 with a 52/36 chainset…and I’m also considering a Cannondale CAAD 10 5 Compact with a 50/34 chainset.

    I am a biker who prefers slower RPM, and a little more pedal pressure, than most people I seem to ride with. It’s not about speed, I’m just not one of those little maniacs whose legs are a blur. I live in the mountains so definitely need some easy gearing for that, but on the flats I prefer S L O W cadences.

    Which gearing is going to be better for me…or are they close enough that I won’t notice a difference?


    1. Depends what you mean by S L O W cadence. A 50×11 will give you a higher gear than anybody raced with just a few years ago. Guess the question is, how fast do you ride. Absolutely serious, this is the relevant question. People tend to think they ride a lot faster than they actually do. What can you maintain for a fair amount of time? Very few of us can maintain 20+mph. A 50×11 would have you “spinning” at only 56rpm at that speed. Barely moving the pedals!

      But here’s what’s likely to happen. Even though 50 makes more sense than 52, if you get the 50, you’re going to be thinking you should have got the 52. That’s just the way things work. You’re going to convince yourself that you actually do need a bigger gear, that all the people who know better don’t know you. The issue is that you’ll give up something at the lower end and you’re going to wish you had that next lower gear on the steepest hills.

      If you were getting a Trek, the answer would be a bit simpler; get the 52×36 with an 11-32 in the rear. But the Cannondale’s chainstays are a bit short for that to work well. OK, just looked it up, the Cannondale’s chainstays aren’t as short as I thought (408mm), so it would likely work OK. But you should get the Trek anyway for the nicer ride. :-) (And yes, I’m biased, I sell Treks, ride Treks, used to sell Cannondale back in the day… in the end, the most-important thing could be the shop selling the bike, which can make a HUGE difference in how well it works and how comfortably it’s set up for you).

      So go for the 52/36 with the option to change the rear to an 11-32 if it turns out you need it. That will require a longer cage on the derailleur and a bit longer chain. Good luck-
      Mike Jacoubowsky, Chain Reaction Bicycles

      1. Thanks for the thoughtful reply, both technical and psychological (obviously you’ve been at this for a while).

        As for RPMs, 80 is high by my standards. (I tried spinning once and found the cadences absurd…but that’s just me.) I don’t race, I don’t ride with aggressive groups. I’m probably below the range of optimal efficiency. Unless I’m climbing Vail Pass, my RPMs are definitely on the low side compared to people around me. It’s just the way I like it. I tend to like a longer crank too, but that’s a discussion for another time.

        I’ll have a look at the Treks. Thanks again for the advice, and the quick response.


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