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Quick update, I'm now running 46x20 FW (that's freewheel) for a singlespeed of 61-62 gear inches.
Its not slowing me down any and if anything, my average speed as increased as I am accelerating through corners and climbing faster than I used to. Squirrelli paced me using his bike computer and we were cruising at 19-21 mph. My cadence was 110 rpm with sprint accelerations to 27 mph (145 rpm). Since its a 20T freewheel, I have no issues with spinning out down hills as I can coast. But I do spinout on the flats now when pushing it. This ratio however is a blessing where I live because there is always a headwind blowing - also much easier acceleration and less strain on the knees. |
46t Eighth Inch front to 17t all-city rear:
https://lh4.googleusercontent.com/-b...%252520013.JPGhttps://lh4.googleusercontent.com/-7...%252520012.JPG 46t Eighth Inch to 14t Dura-Ace rear: https://lh5.googleusercontent.com/-y...%252520014.JPGhttps://lh4.googleusercontent.com/-U...%252520011.JPG Just wanted to share, at least with the Brassknuckle, that the difference between a 14t and a 17t is roughly 1/3rd the dropouts |
For me, the stock 48x16 on my Bianchi Pista is OK for a track workout without running out of spin, but its 81 inches is too high a gearing for riding around the neighborhood and city. It's relatively flat in the city here and gearing down to 48x18 (~72") is working well for me. There are some good rollers with short but steep grades in the rural areas. I'd have to gear the fixie down further for that, probably by another 8-10 inches into the mid to low 60's.
I share the observation that spinning faster, including on a road bike with a triple chainring and 10 cogs, goes faster. I see too many guys around here mashing their geared road bike pedals with slow cadences when they could be faster if they geared down a cog. Frequently riding a fixed track bike helps for smoother spinning on a geared road bike. FWIW I'm 58, nearly 59. Great to see this sticky on gearing with its use of gear inches! |
I am running 46/18 - 69 inches on the fixie I just completed - it is my first build at 50 yrs old. 15 miles ridden to date, with this AM being my first commute on the bike. There are some small hills on the route and building up speed leading to the hill resulted in minimal effort on the climb. Feels good in the flats as well. I have a brake and coupled with pedal resistance have not had any issues going down steeper hills either...
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Running 45/17 here in Maine. Seems good so far. New to fixed gear with in the last 2 month's at 53 yrs old.
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Running a 46 15/17 flipflop, with the 17 being a freewheel. With 700 tires, that puts me at about 81/71.
I'm up northern Indiana. No hills to speak of, and the wind isn't too bad, though given that this is my first ssfg bike, I wish I would have gone a bit lower, but I enjoy it well enough. Thanks for the thread! |
Question about gearing. :)
From experience on my geared bike 38 with 15 is almost perfect. That's arount 67 gear inches. A bit hard to start from traffic light, but I quickly build up revs and soon almost feel I need a higher gear. Nearest higher is about 71 gear inches (48 with 18) and higher than that is some 77 gear inches (38 with 15) which is too much 99% of the time (except when going down hill). According to this, on a single speed, guess perfect would be 44/17, or 48/19 (if there is such combination). Is this OK for flat in town use? |
Originally Posted by puppypilgrim
(Post 12506287)
Permit me to add to this discussion. Use the formulas referenced in the posts above to calculate what chain rings and cogs you need.
Online calculators are available here: http://software.bareknucklebrigade.c...it.applet.html (does not work with Google Chrome) http://www.sheldonbrown.com/gears/ Your preferred gear inch will depend on: - how fit you are - how strong you are - the terrain you do 90% of your riding - the wind conditions for the majority of your riding - how many skid patches you want (if that's important to you) Since most riders cannot perceive a 1 gear inch difference, consider the following gear ranges with soft edges, not binary precision. 60-65 gear inches = good for older riders or weak knees or touring. 66 gear inches = good all round gear for flats and hills. Not too slow on the flats, not too hard on the hills and wind. Touring is even possible. Great acceleration from standstill. 69 gear inches = near ideal for most people and most applications unless you are exceptionally strong. City gear and hills are feasible. 70-73 gear inches = superb range. At 100 rpm, it produces 21.4 mph (34.5 km/h). At 100 rpm, the force required to turn the pedals is still relatively light. Anything is this gear range produces an excellent balance between acceleration, hill climbing, combating winds and flat road speed. Note that at 20 mph (32.2 km/h), approximately 80% of the power being produced by the human body is being used to overcome air resistance. This is why it is so hard to sustain any speed above 20 mph (32.2 km/h) during a daily commute. If you know how to spin, this gear range will not be slowing you down. 76 -81 gear inches = this range maybe useful in places where there are no hills and where riding with a slow cadence is preferred to riding with a rapid cadence. All other things being equal, one will sweat less pushing a larger gear with a slow cadence at low speeds (say up to 15 mph) versus a lower gear with a high cadence. All bets are off if you push a large gear with a high cadence! This range is also harder on the knees due to the pedal force required to turn the cranks. Acceleration from a standstill will be noticeably slower than gears in the high 60s and low 70s. It's a tall gear for city riding and sprinting from traffic to traffic light and intersections. Hills will also slow you down in a big way. 81 and up gear inches = velodrome racing gears in controlled conditions, and short term training applications. These are my opinions only based on general observation, lots and lots of reading and learning from others who have gone before. Victor Ian |
For those doing vertical dropout conversions, this page is amazing!
http://eehouse.org/fixin/fixmeup.php |
is 51.9 a good starting point for gi on a mtb?
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Sounds like a pretty good spot. I tried 55.5 on my 26er and found it too high to get up some hills. But it was pretty close to what I want.
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Great thread!
I'm currently running 46/16 on 700x35c tires (78.1 GI according to bareknucklebrigade.com's Rabbit). Great on flats once I get going. Not so great acceleration compared to other riders I see. And a little tougher than I want on hills. Question... I'm going up to 17T (73.5 GI) because of the hills and lack of acceleration. I have a flip flop hub though, so I'm wondering what I should put on the other side. Would going up to just 18T (69.4 GI) on the other side make sense? Should I go up 2 teeth with my "other" gear? 46/19 would put me at 65.8 GI. I'm not old nor do I have bad knees (Puppypilgrim's ranges). Also, how much would I be moving my axle in the track-end flip flopping to 1-2 more teeth? Switching to bigger tires had me add a half link and move the axle about 2/3 of the way back in the track-end, so I don't have much room to play with. This will be freewheel/freewheel by the way. |
It looks as tho my photos got their links cut... but I was able to get 3 teeth difference on mine (14t vs 17t) but if I were you, I'd go 18. That way, if it does feel too easy, you can always swap over to the 16 side.... Though I am a huge fan of low gears and spinning
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hai uncle 60
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My current gearing is 52x16, 85.7 GI. I'm buying a new crankset, comes stock with a 46t chainring. If I throw a 14t cog on the back, making it 46x14, 86.7 GI, it should perform pretty much the same, right?
Someone second me... |
Originally Posted by bigbris1
(Post 13707275)
hai uncle 60
Rehabbing those knees ? |
These are excellent descriptions! I went with 46/17 (73.5 GI) with a bailout of 46/19 (65.8 GI) on 700x35c tires.
Originally Posted by puppypilgrim
(Post 12506287)
60-65 gear inches = good for older riders or weak knees or touring.
66 gear inches = good all round gear for flats and hills. Not too slow on the flats, not too hard on the hills and wind. Touring is even possible. Great acceleration from standstill. Not enough GIs to be my all around gearing though. A little too much spin on flats. I'll see if I'm up to switching gears for the commute home everyday.
Originally Posted by puppypilgrim
(Post 12506287)
70-73 gear inches = superb range. At 100 rpm, it produces 21.4 mph (34.5 km/h). At 100 rpm, the force required to turn the pedals is still relatively light. Anything is this gear range produces an excellent balance between acceleration, hill climbing, combating winds and flat road speed. Note that at 20 mph (32.2 km/h), approximately 80% of the power being produced by the human body is being used to overcome air resistance. This is why it is so hard to sustain any speed above 20 mph (32.2 km/h) during a daily commute. If you know how to spin, this gear range will not be slowing you down.
I can't wait to try both gearings this weekend in the park. I'm guessing 46/17 will be near perfect; great on flats and quite challenging, hopefully still fun on the inclines. While 46/19 will be great for the inclines and not so great on the flats and declines. I'm sure it will be fun trying both. |
I started on 46/18 with single and dropped to 46/17 on my first fixed setup. its good so far.
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Originally Posted by GENESTARWIND
(Post 13841514)
I started on 46/18 with single and dropped to 46/17 on my first fixed setup. its good so far.
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When I first starting riding fixed (around town not on the track) it was a 47/16 which is a 77.5, and I found it too low. Maybe I wasn't used to spinning so much, I felt like I was topping out and I couldn't go faster.
After awhile I upped it to a 47/15 (82.7) and I kept it at that. I ussualy ride about 20 miles a week commuting back and forth from my girl friends, my ride home has a pretty steep hill, but not that bad (~500ft climb total distance), and though I had to really push up the hill, I was OK with it. When I built my new all city bike the chain ring I got was a 46, and I ordered a 15t and 14t for each side of the rear cog. When I first put it together I ran a 46/15 (80.9) which was actually pretty nice around town. A couple weeks ago I flipped my rear tire to the 14t and have been riding the 46/14 (86.7) around town since then, and I honestly feel a bit slower on it than any of my other ratios. I just can't keep up my spin at that ratio, not in the city anyways. So now with all this knowledge of what its like -for me- to ride a 77.5,80.9,82.7, and 86.7 I feel like for me something in the high 70s low 80s is ideal for me. I'll probably switch my hub around and ride the 80.9 for around the city. My whole point in all of this is that its important for YOU to try a bunch of different ratios. I personally feel like @Sixty Fiver and @puppypilgrim recommendations are a little too low for me. But most of my friends actually ride between a 70-75 tops and most other forms I read people talk about 75 being too high for them. Is it just me or does anyone else get frustrated at low to mid 70s? Seems like I might be an outlier, or maybe I haven't figured out/don't want to spin that fast to go fast. ;) |
Originally Posted by blissofbeing
(Post 13936167)
My whole point in all of this is that its important for YOU to try a bunch of different ratios. I personally feel like @Sixty Fiver and @puppypilgrim recommendations are a little too low for me. But most of my friends actually ride between a 70-75 tops and most other forms I read people talk about 75 being too high for them. Is it just me or does anyone else get frustrated at low to mid 70s? Seems like I might be an outlier, or maybe I haven't figured out/don't want to spin that fast to go fast. ;)
I also use to ride at 80 gear inches and laid down the same mileage... dropping 4 gear inches just let me spin up a little faster and did not affect my top speed save for the fact I could hold it longer and keep things steadier over varied terrain. |
what range is my gear ratio? im running 48-18 just droped down from 48-16.
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Extra medium.
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Originally Posted by ATleastHEtries
(Post 13955071)
what range is my gear ratio? im running 48-18 just droped down from 48-16.
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so right now I run a 17/46 and I may be picking up omniums on the super cheap but it has a 52 chainring. what size cog would I have to drop to, to keep the same setup?
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Originally Posted by GENESTARWIND
(Post 14121439)
so right now I run a 17/46 and I may be picking up omniums on the super cheap but it has a 52 chainring. what size cog would I have to drop to, to keep the same setup?
46/17 = 71.4GI 52/18 = 76.2GI 52/19 = 72.2GI 52/20 = 68.6GI Take your pick. |
52/19 is just a hair larger.
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so 52/19 I shouldn't notice much of a difference?
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Originally Posted by GENESTARWIND
(Post 14121462)
so 52/19 I shouldn't notice much of a difference?
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turns out the crankset i bought had a 49, not a 52. so ill be running 17/49 for now, see how i like it and maybe ill jump up to a 18 later i dunno..
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