# Single Speed gearing



## stunzeed (Jul 27, 2007)

*Single Speed Gearing for Flats and Climbs*

Trying to find out the ideal gearing for a single speed commuter/road bike. My commute is flat but during winter times I plan to do a little longer rides with some climbing (gravel roads).

I am an average rider, I like to have extra gears as I run a compact crankset and a 12-30 cassette on my road bike.

What would ideal chainring and rear cog for this type of riding.


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## Nubster (Jul 8, 2009)

I'm sure it's a little different but I run 32x19 or 32x18 on my SS mtb. That's on relatively flat ground with some steep short climbs. I ride it around town as well. Does well for me.


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## stunzeed (Jul 27, 2007)

This will be on a cross bike, but I do not race cross. I am thinking a 42x17 but curious as I really don't have experience with this


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## UrbanPrimitive (Jun 14, 2009)

That's a good question. What is the ideal gearing for that sort of riding where you are?

Pretend your geared bike is a single speed. Crunch the numbers on Sheldon's site to work out the gain ratios or gear inch combinations your considering. Shift to the closest match on your current cassette and try it out for a day or two. That will narrow down your window very quickly. After a week or so of experimentation you'll probably have a pretty good sense of what gear combination will work best for you.

There isn't really a "right" answer for this. It's all about you, your legs, and your roads.


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## OldZaskar (Jul 1, 2009)

On a flat route, 42:17 would feel like your chain fell off. MTB is not a great comparison... anything near 2:1 is a good starting point on the trail. But anything near that on the road is going feel like you're spinning and going nowhere. I live in Atlanta (very hill, not SF hilly, but hilly) and started with 52:18. I was spinning out on those slight descents where you still pedal and getting dropped by the groups. So, swapped the 18 for a 16. That turned out to be the perfect amount of "gear inches" for my route. 

There are a handful of online calculators, but there's really no way of doing this without experimenting. Is the 42 a given, e.g. is that staying and you're looking at the right cog? If so, maybe try a 42:16 or 42:15


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## JCavilia (Sep 12, 2005)

It's easy to test. Put your road bike in a gear and ride the routes without shifting. Try various gears until you find the one that's the best compromise.


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## bikerector (Oct 31, 2012)

42:17 or 42:16 would be decent for general riding and gravel roads. Use the "speed at cadence" spot. Most riding is done in the 80-100 rpm range climbing on ss is often the 50-60 rpm and spinning out is 120-130 rpm. This depends on the person of course. I was able to keep up with a group ride in the 23mph range on slight down slope with 40:18 (CX race gearing) and it was horrible, you really want to be able to take a break on the flats after hitting hills. Having said that, it was a group ride so I wasn't fighting headwinds. I think 40:16 (not much different that 42:16) would be a very good road gearing. For gravel road, maybe add a tooth in the rear. I'm more of a spinner than a masher (especially ss), take you're pedaling style into consideration.

Here's a good calculator: BikeCalc.com - Fixed Gear Calculator

Agree with above, use you're road bike as a test and go from there.


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## JCavilia (Sep 12, 2005)

OldZaskar said:


> On a flat route, 42:17 would feel like your chain fell off. MTB is not a great comparison... anything near 2:1 is a good starting point on the trail. But anything near that on the road is going feel like you're spinning and going nowhere.


I don't think you can say that so generally. It really depends on the rider. 42x17 is about a 65-inch gear. At 90 rpm that gets you about 17.5 mph. If that's your cruising speed (we're talking about a solo commute here, not a group ride), or if you like to spin (105 rpm is over 20 mph with that gear), that gear might be fine. Your 86-inch 52x16 would be a very tall SS gear for most riders.


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## Mike T. (Feb 3, 2004)

JCavilia said:


> It's easy to test. Put your road bike in a gear and ride the routes without shifting. Try various gears until you find the one that's the best compromise.


Errrr yeah, precisely. There's only one person who knows what the right single gear is for the OP. The OP.


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## Jay Strongbow (May 8, 2010)

I think you're trying to get blood out of a stone here. 
There is no ideal gear for both flat commuting and climbing gravel roads. The ideal for each of those is pretty far apart and the middle point between them wouldn't be very good for either.


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## OldZaskar (Jul 1, 2009)

yeah... you're right. I was thinking that with the flat, the bigger gear would be better. But, I didn't really think about the solo v group. Solid point.

And yeah, the 86 gear inches is up there, but needed to hang on those group rides. Hills are a grind.


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## JCavilia (Sep 12, 2005)

Jay Strongbow said:


> I think you're trying to get blood out of a stone here.
> There is no ideal gear for both flat commuting and climbing gravel roads. The ideal for each of those is pretty far apart and the middle point between them wouldn't be very good for either.


I'll take issue a little bit with that. By their very nature, the gearing of a SS or FG bike is a compromise. Compared to the gear you'd select at a given time on a shifting bike, on a SS you'll often -- maybe even most of the time -- be in the "wrong" gear. You choose the compromise to get you in a "good" gear as much of the time as possible, while still being workable for the extremes. How bad the compromise is at one end or the other will depend on your preferences and ability. I don't think it follows at all that he can't find a gear that works well enough for these various rides. A gear that's just barely low enough to manage "some climbing" on gravel roads might be manageable on the flat commute, especially if he likes to spin. 

It's a good bit easier to find the compromise with SS than with FG. You can get away with a lower gear, since you can coast the descents.

Stunzeed, since you say you only plan to do the gravel roads for part of the year, you could get two freewheels (some are pretty cheap), and run a lower gear in the winter.

Anyway, I agree with the advice of some others here that a good starting point is a 65-inch gear (about 42 x17). Figure out which gear on your road bike is closest to that and go ride all your routes. Try higher and lower, and you should be able to dial it in quickly.


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## bikerector (Oct 31, 2012)

If using a freewheel, you might consider looking into the white industries dos freewheel. Gives you two gearing options with little fuss. I know a few ss mtb'er that liked them.

White Industries - Free Wheels


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## stunzeed (Jul 27, 2007)

Thx all - think I'm going to try the 42x17 .


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