donovanjdouglas

I'll go ahead and open Pandora's box. I just got this pretty awesome 2001 Bianchi Pista but the gear ratio is a tough 48x15. I've been out of the fixed gear game for a few years and don't have hulk legs, so I was thinking either 48x17 or 48x19 would be easy to get back into, decent for city riding, and would give me a good number of skid patches. The city is fairly flat but there are some gentle and steep slopes here and there. It is Oregon after all. I have limited funds and don't want to swap out chainrings, hence the cog. According to Sheldon Brown's Gear Calculator (with 165mm cranks, 23c tires), 48x15 is 84.1 gear inches. 48x17=74.2 GI. 48x19=66.4 GI. I used to ride 42x17 (64.9 GI) in a very hilly city and liked it, but I wonder if 48x19 will cause me to spin out on flat ground, hence the 17t cog. I can spin but also don't want my legs to be egg beaters at 20mph. Any advice is appreciated.

prooftheory

48x19 is very comfortable at 20 mph. Did you read this thread?https://www.bikeforums.net/showthread.php/716371-Uncle-Sixty-s-Gearing-Primer-for-Newbs

Mumonkan

after being off my FG bike for about a year i resurrected my beater with a 50:21 ratio which comes out to about 67 inches with 32's. its comfy for quick little blasts but downhills are too spinny for me

on my geared bike i find myself mostly in 42:15 combo which is around 75 inches and the same size tire and seems perfect for flat ground and i dont find it hard on the hills on my commute

depending on what bcd your crank is, a chainring isnt always more expensive than a cog. surly makes nice cheap rings in a variety of sizes, or amazon has lots of sugino rings that are dirt cheap too

just some food for thought

ps: this little applet is a great calc for skid patches gain ratios inches rpms and anything else youd wanna know

donovanjdouglas

Good to know. I didn't see it in my forum search for "gear ratio." It was helpful. I have a good technical understanding of gear ratio, I guess I'm just looking for opinions and what others ride.

donovanjdouglas

Thanks, Mumonkan. I guess I'm leaning toward 48x19 as I'll still have the 15t cog I could throw back on. I love having one gear, the trouble is finding what feels right.

Mumonkan

thats really up to you and could take some experimentation. i read somewhere to take your height in inches and that would be an "optimum" gear inch for your bike. of course everyones subjective but it seems to be pretty true for me (tho i prefer a bit taller by a few inch, since im 70")

TenSpeedV2

I jumped into the fixed gear game at 46:16 and it wasn't enough for me. Flat terrain here for the most part. Currently 49:15 on both bikes. You can ride 48:15, no need to swap anything out.

hardboiled718

48:19 seems like a good ratio to try, I doubt you'll be spinning out on on flats unless you're sprinting, even then. It's good to spin a smaller ratio at a higher cadence, better efficiency and easier on the knees. Also the lower gear will allow you to accelerate from a stop faster, easier to skid and control the bike overall in city traffic. I used to run a tall gear (49:14) but it was definitely track gearing not really conducive for street use.

donovanjdouglas

Thanks for the input.

Mumonkan: that's pretty cool, never heard of that. I'd be around 72". Could be right, at 48x17. Dunno. I've ridden a lot of different ratios, even a crazy 52-13, which was great on the downhill at around 40mph with no brakes. Only on the late night though of course. Most I rode was 46-16 and I loved that ratio. But that was some time ago.

Tenspeed: haha. I -can- ride it. It just feels like I've got someone holding onto my legs. Hard on the knees, too.

Hardboiled: I agree. I enjoy spinning and enjoyed 42x17. But like I said that was very hilly.

Flatulentfox

I run 48x19 most of the time. I find it is comfortable for general riding/commuting in hilly terrain with an average speed around 16 mph and is manageable with quick 30mph bursts down hill.

I have a 17t cog on the flip side for flat rides.

Huffandstuff

Not sure where in Oregon you are but 48x17 is a pretty common ratio among the people in PDX, I used to run 48x19 and loved it. It really just comes down to preference but I agree 48x15 is far too big for the streets.

Night_shift

48x17

Surly2698

I used to commute 38 miles round trip in Denver with a 48 15
I was not able to recover from day to day
Most of the time I was tired
I lower the gear to 48 17
I am a lot faster and less tired
Just my 2 cents
Good luck

donovanjdouglas

McMinnville, an hour southwest of Portland. In the valley, so lots of gradual rolling hills and flats. Nowhere near as hilly as Portland. I'm leaning toward 48x19.

donovanjdouglas

Ugh. I can't imagine commuting on 48x15. Glad to hear you made the switch. Thanks for the info.

Huffandstuff

Yeah, you'll be fine on 48x19 but if you have a flip flop, you should keep a 17 on the other side in case you want to head west, out to the coast since that's a flat ride.

donovanjdouglas

Which highway are you talking, 26? 18 is a little bit /\/\/\. I'd love to do that on a fixed though.

That's a fantastic idea, huff, doing a 19/17 flip flop. Thanks.

Huffandstuff

I've done it on the 18 to the 22 and the then connecting to the 101. It's not too bad in my opinion, pretty wide shoulder and just rolling hills, no real step steep hills.

GENESTARWIND

48-18

xscottypx

mine is a 46-15

i have been getting crushed on hills though, and my legs are decently strong. picked up an 18t which i will play with and adjust. i am new to the single speed game so i am clueless on these ratios

Pixieshakes

Thats me at the moment too. Started with no idea at 48-22 on the new bike this year but didn't last long. Might try a 17 at some stage too.

donovanjdouglas

@Huffandstuff That's awesome. I'll have to check it out.

donovanjdouglas

@xscottypx That's a -big- ratio to start with. Not much smaller than my 48-15.

I'm avoiding even numbered cogs for more even tire wear. 18t is 5 patches isn't it, on a 48? Whereas 17 is 17 and 19 is 19. I'm not a skid demon by any measure but I do enjoy it and would like my tire to last.

xscottypx

guy that sold it to me said he could not stabd doing hills with it, i shugged it off. he was right.

i dont skid stop though. adding free wheels though. curious if i will need a rear brake along with front

donovanjdouglas

For a single speed you'll definitely want two or at least a rear brake. Just a front works differently on a fixed gear. I'm sure someone could give you a technical explanation why.