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.
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.
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.”
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-
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!
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.
Some people do need big gears:
http://vimeo.com/70921986
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–
I prefer a 45tooth front sprocket and a16 tooth rear but that’s when I m peddling a bmx however my question was if I put a 20 in rim on the back in place of the 26 inch rim that is already there with the same size sprocket what would be my speed if my speed was 30 miles per hour with the 26 inch rim this is a motorized bicycle so I’m not pedaling it the motor is pushing it will the smaller Rim increase my speed or reduce it
Now that folks have “read it on The Internet” they will believe it. :-/
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?
Thanks
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
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.
Wing
plz suggest me that there is possible 60 teeth on front and 12 tooth on rear in a bycicle. or
suggest me that if we can produce 80 rpm from pedal hub then by using gear system which can produce min. 800 rpm output. what is the gear dimensions of both rear and front
I’m not sure if this is a word problem or simple math question. Either way, I’m out!
From my understanding the 50 /13-14 combination is true for 700cc wheels .what about 20″ wheels( folding bike) would 56 or 60t chainring make more sense? I can generate quite a high cadence on 52 11 and feel I need something higher . I just can’t decide if I should go for 9t Shimano caprio sprocket with a hub or just get a 60t chainring. My current gears are 11-32. Thanks for any inputs.
If you have the Caprio option, absolutely go that way! Your front shifting will be so much better with “normal” chainrings. The 9t small cog option on the Caprio pretty much perfectly mirrors the gearing you’d have with a normal cassette on a 700c wheel. The downside is the limited supply of Caprio equipment; it’s only available in 9 speed, so to make a 10, you have to cobble together pieces from different cassettes (that’s what Bike Friday does). –Mike–
What kind of gearing would you need to get to 20-mph on a mountain bike with 26″ inch rims?
or is it just not going to happen?
20mph on a mountain bike shouldn’t be all that tough. You lose maybe 15% for the wheel size, so I figure if you’ve got a 46 up front with an 11 tooth in the rear, that should be more than adequate. The issue is that you can’t do it at a really low cadence, but then again, you shouldn’t want to. –MikeJ
I run a 29er 1×9 setup with a 36 on the front and a 12/36 cassette on the back I ride with alot of road and touring bikes and I am probably one of the faster riders .
Hey Larry,
I’m from India and share your views too; I’m awaiting delivery of a 12-36 9-speed to use with 34-50 upfront on my Scott Speedster 40.
The only tours I’ve done – http://www.toursofnilgiris.com. You may like to come some day.
Chandi
I had a mountain bike a Yukon Giant, I use to ride it to work 20 miles a day in the highest
gear, my legs or thighs got to be giant…
I’m building a low profile long wheel base recumbent with 20 inch wheels 50 39 30 crank set and 12-25 11 speed cogs and I was thinking with a 30% reduced wind resistance should I go to a larger chain ring rather than a smaller cog to reduce ware on the cog
I have a folding bike with 20″ wheels and 48 / 13 lowest gearing. Even on the flat I find that im spinning-out on the lowest gear. would this be an instance where a bigger ring up-front would actually be beneficial? – T
Folding bikes with smaller wheels are often lacking in having an appropriate gear range to mimic normal riding on a full-size-wheel bike. It’s simple physics. 48/13 is going to be, for many, too low a gear on a bike with 20 inch wheels. Bike Friday tackles this with the Capreo rear hub option, which allows you to go to a 9 tooth. You may be able to increase the size of the front, but easier to see if an 11 tooth is available for the rear; that would make a very big difference and would be easier to implement (if available) than changing the chainring. I would consult with a shop that sells your bike and see what option might work best. But yes, in your case, higher gearing WILL be better. 🙂
Would swapping out the 50/34 crank on a cyclocross bike for a 46/36 give me more speed on the road and better climbing ability?
Currently on a 105, 11/32 groupset.
Thanks
Sorry, other way round on those numbers! Duh!
I think 50/34 makes a lot more sense for road use than the 46/36 traditional ‘cross gearing. More high, more low, maybe a bit bigger gaps in between but you could always swap to an 11-28 in the back if that was an issue (and you didn’t need the lower gear). Changing ‘cross bikes to “road” chainrings is a pretty common thing to do. –Mike–
Happy days man, i appreciate the advice 😉
I ride a steel frame 56/11 fixed gear in the urban jungle of Brooklyn. There are many challenging hills but I can usually maintain an average speed of 15 mph up a 1/2 mile. Can average 21 -22 mph over 3 miles on the flats, but 18 mph is easily attainable for longer stretches. I must admit it is not easy but this is a riding style that is enjoyable for me.
As I said, the bike is a steel frame Iro. Carbon fork. Aluminum crank set & headset . All powder coated. Aluminum Dura Ace 56t chainring. Aluminum Jalpa wheels. Aluminum Nitto seat post. Thickslick tires by Freedom. All in $1300 22.5 lbs… including custom powder coating.
The tires are heavy but at speed they do actually help propel you forward. I know that it sounds like an insane gear ratio but I get the best feeling running down a a 5k or better bike without having to have my legs spinning like his will soon be as I pass him. lol.
I don’t race, I just enjoy biking. I don’t do any long distance travel. My normal ride is only about 80km (50American), and a long ride for me is only 300km (190American) I ride a 52/11 and have for years and I spend less than 10% of my time with an ‘easier’ gear. So I plan on going to a larger front gear. When I get up to a crank speed that I’m told I’m supposed to do, my legs get extremely tired very quickly. I’ve tried several times over the years, and my legs just get tired at high crank speeds.
I always find it funny when people tell me that ‘so and so professional/legendary doesn’t need a higher gear so it won’t be any benefit for me either’.
I figure they like apple products too: One size fits all, no one needs it if Steve Jobs didn’t need it.
So – if you are a lurker and you want a higher front gear – go ahead and try, see if *you* like it. Don’t assume that because it is written on the internet that means it is true. As for me … my next will be something like a 56/11 and I’ll see if I can finally start riding all the time in something other than the highest gear.
FWIW, my average speed is 26km/hr and my son 30km/hr. And I *love* biking for hours at that speed in these supposedly incorrect gears/cranks speed.
My bike just got stolen; I had been riding 56/11 for 12 years and loved it. Did I ride that gear all the time? No, but usually around 40% in the flats, depending on the wind. BUT certainly downhill!
No, I did NOT race, but I certainly enjoyed passing those super equipped Sunday racers on my commuter bike to and from work, going slow motion while they were working the spin.
Now I am trying -and the bike shop that is currently building my new Trek 520, is not succeeding- to upgrade to 60/11 (would so love to go 60/10). We still have not resolved the shifting issue.
Will this be my everyday gear? Probably not; but having the option is great, no matter what those racing ergonomic specialists decide for their optimum performance analysis.
Hi Mike,
I have an ebike that goes up to about 45mph and I want to add some leg power to improve battery efficiency and get some excercise. I have ~22inch tires and 12t and 52t is not cutting it for me. What size crankset will I need to get a good cadence between 30-40mph?
Will I need to go to 80t? Any recommendations?
Many thanks,
Loysius
Below is an explanation for why it’s not reasonable to change gearing that would increase your top-end speed, but that wasn’t really your question; you asked about adding leg power at lower speed. In the 30-35 mph region, you could probably get what you need by switching your rear wheel to something build on a “Capreo” hub, that allows a 9 tooth small rear cog. If you did that and changed the front to a 64t, you would see a marked improvement in capability in that range. If you switch just to the 80 front, you might get there as well, but that 80 front might caused drivetrain issues (not sure if you have a front derailleur on the bike).
For the person just trying to max out speed…
Something capable of running at 45mph doesn’t fit into the normal criteria for equipment used on a bicycle. Plus the physics involved in going at that speed require such a huge amount of motor-supplied power that I doubt human input is going to make much of a dent in terms of added capability. Check out this site for an example of how much power it takes to go a given speed. If you plug in 25mph, the default example requires 379 watts of power. That’s a LOT. But at 45mph? 2025 watts!!! Let’s say you’re an elite professional athlete and can actually add another 379 watts to the system. At 2,404 watts total, you can only add another 2.71 mph.
This assumes a conventional racing bike. If you’ve got a bike with upright handlebars, it gets worse; you might work your butt off for an additional 1 mph. If you’ve got a wind-cheating recumbent, you might do much better.
But overall, if what you’re riding is capable of 45 mph with its motor, it really isn’t following the rules and physics of a typical bicycle.
I have a recumbent trike with a fixed front of 42 and a nu Vince 360 in the rear. 20″ tires all around and I need lower gears for hills and want a bit more speed. I was told a Patterson metropolis (46,28) would be too hard to pedal. I was thinking this would give me a bit higher gear and the badly needed lower gear. Thoughts and suggestions please . I am a novice.
Either a smaller chainring up front or larger rear cog. As long as it’s not belt drive, it’s not too expensive to try out; you’ll want at least a 10% difference (decrease in chainring size or increase in rear cog size) to make a difference you’ll notice. Obviously you’ll be giving up that much at your high end, but that’s not a big deal for most. Sorry I didn’t notice this post earlier!
For achieving best cadence result of 80~100rpm in cycling, should i combine Bigger front Chainring (T50) combined with Smaller rear Sprocket, OR, Small front Chainring (T36) with Bigger rear Sprocket?
It really doesn’t matter how you get there. If you’re looking to save the last fraction of a watt, larger rear cogs are slightly more efficient than smaller ones. Slightly. As in, it shouldn’t matter to mere mortals.
I appreciate this article. I was thinking about upgrading to a 50t or 52t, but after reading this I will stay with my 48t. At the very most, I’ll only upgrade to 50t.
Thanks
I have a KMX Tornado Trike. 6 speed. 20″ rear and 16″ fronts. Front sprocket is 42 tooth, and my lowest geared sprocket in the rear is 14 tooth. Which direction do I go to get a higher top end speed? Larger front, or a Smaller rear, or both?
The best way to increase your gearing is going to depend upon whether it’s easier and cheaper to change the rear cogs or the front chainring. Changing from a 14 in the back to a 13 will get you the same difference as changing the front from a 42 to a 45. You’re still fighting a pretty low gear though, given the wheel size. If the rear hub is a cassette-type mechanism, then I’d change that first, since you can go all the way down to an 11 and make a really significant difference for not much $$$.
Best bet would to be bring it by a shop and see what they have to say about it. Hope this helps-
http://www.roadbikereview.com/reviews/video-how-fast-can-you-go-with-an-104-tooth-chainring
ummmmm, i think a bigger chainring equals faster, 104 tooth chainring.
Good grief, I’m going the other direction. At 75 yrs old, bad hips, no power in the legs, hilly terrain, going as low as I can. Oh, and no computer anymore either, just happy to still be biking, enjoying the ride. Ya’all be there too someday, unless you crawled out of some magnificent gene pool !