Tell me if you think anything is incorrect or wrong with this.

Common Gear Ratios equal to the common 16/44 (2.75)

7 - 20/21
8 - 22/23
9 - 24/25
10 - 26/28
11 - 29/31
12 - 32/34
13 - 35/37
14 - 38/40
15 - 41/43
16 - 44/46
17 - 47/48
18 - 48/49

All of these combonations are somewhat interchangeable as long as it isn't a very drastic amount of tooth differance.

Also the tire and rim size will slightly affect the ratios. A larger tire (how tall it is not how wide it is) will have a higher turning radius than a smaller one making the ratio slightly higher.

A Chart to quickly configure the ratio that is best for you is at http://www.danscomp.com/products/charts/gearchart.htm

The combinations stated above are the most widely used and accepted in BMX, but some may prefer a somewhat different ratio pending on their riding style, skill level, or personal preference.

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To set the record straight on the meaning of gearing,

A HIGH gear ratio is one that is harder to pedal, but gives you a HIGH top speed. Low Acceleration/High Speed
This gear ratio is ideal for downhill bmx tracks or some trail riding.

A LOW gear ratio is one that is easier to pedal, but you have a LOW top speed. High Acceleration/Low Speed
This gear ratio is ideal for flatland or technical mini-ramp riding.

Having a higher tooth count in the rear than what is stated will result in having a LOW gear ratio.

Having a lower tooth count in the rear than what is stated will result in having a HIGH gear ratio.

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To have a specified gear ratio, certain parts are needed.

Rear Tooth Count Hub Required

7 - Cassette (one piece driver)
8 - Cassette (one piece driver)
9 - Cassette (one piece driver)
10 - Cassette (one piece driver)
11 - Cassette (cog or one piece driver)
12 - Cassette (cog or one piece driver)
13 - Flip/Flop Hub (small side, freewheel) Metric 30mm
14 - Flip/Flop Hub (small side, freewheel) Metric 30mm
15 - Flip/Flop Hub (large side, freewheel) Imperial/American
16 - Flip/Flop Hub (largel side, freewheel) Imperial/American

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Crank Arm Length

Crank size normaly is associated with the inseam lenth on your pants. Most people prefer a length around 175 millimeters.

Rider Inseam Crank Lenght

20" 140mm
21" 145mm
22" 150mm
23" 155mm
24" 160mm
25" 162mm
26" 166mm
27" 171mm
28" 175mm
29" 177mm
30" 180mm
31" 182mm
32" 185mm
34" 190mm

Different people and different riding style may prefer a different length.

Crank Size has an effect on gear ratios.

Having say a 185mm crank arm length gives you better leverage, requires more up and down movement, easier to pedal, and your bike will tend to have better acceleration. Problem is longer cranks are easier to bend and break. Plus you would have to pedal faster to keep up with some one with a 175mm crank if both of you where pedaling at the same speed,

Having a lower crank for example like a 160mm arm length you do a lot less pedaling, but you have to pedal harder. You will also have a slightly higher top speed.

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Consequences of Micro Gearing.
By gearing your bike with the new trend of "micro gearing" you may incounter several unfortunate events. Here are the three major points.

1) Smaller gear systems result in smaller clearences between the brake post and the chain. (assuming you have chainstay brakes) To counter this, many people will buy new U-brake (Fly U-Brake) that has a overall lower stack height therefore freeing up valuable space between the chain and brake post. Others tend to cut their brake posts off completely and run brakeless. Any gearing below 30/11 will usually hit the top of the brake post without the brake on it.

For every tooth lost from the front sprocket the top run of chain will move down closer to the chainstays (or brake boss) by 0.08” ie.3 teeth causes a drop of about ¼(quarter).

2) Having fewer teeth in the sprocket and fewer on the driver, cog, freewheel, will require that the load be placed onto the teeth of these components to greatly increase. So instead of having the load being placed on 8 or 9 teeth like on a 16 tooth freewheel, it must be placed on only 4 or 5 teeth like that of a 9 tooth driver. The result is haveing a drivetrain that wears out quicker, is less durable, and isn't as strong as that of a higher gearing system. Not to say these forces of load placement and/or strength are in great measures, but enough to take into consideration.

3) Similar to the teeth on the sproket and drivers, the chain takes a blow from the smaller drivetrains. The chain has to carry the load of propeling the bike not only in fewer links, but a greater load all together. A chain will wear out faster on a "micro" gearing setup than a drivetrain with say a 39/14 gear setup. That being said, you WILL have to replace chains more often.

4) Cassettes may cost more than a flip/flop (freewheel) hub. And are typically louder. (although many people consider that to be a plus)

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I hope this simple guide to Gearing will answer any questions you have concerning Ratios, Brake Clearence, Crank Arm Length, etc. But if you have a question that I so hoplessly failed to answer, please feel free to ask.

-FLATLINE

You seem to be off on the crank stuff.

Thanks, any more corrections?

Having say a 185mm crank arm length gives you better leverage, requires more up and down movement, easier to pedal, and your bike will tend to have better acceleration. Problem is longer cranks are easier to bend and break. Plus you would have to pedal faster to keep up with some one with a 175mm crank if both of you where pedaling at the same speed,

Having a lower crank for example like a 160mm arm length you do a lot less pedaling, but you have to pedal harder. You will also have a slightly higher top speed.[/COLOR]



Want to try again?

hey whats a good "tight" trail ratio? i have like a 100 tops, prolly 80foot run up to our first double and my gearings pretty high..so any ideas on gearing changes? thanks

hey whats a good "tight" trail ratio? i have like a 100 tops, prolly 80foot run up to our first double and my gearings pretty high..so any ideas on gearing changes? thanks

How long is a piece of string? We need more info. How long are your cranks, what gearing do you currently run, and how strong are your legs? I tend to prefer a numerically lower cog, as I've got the leg strength, 180mm cranks, and want to cover the most distance for each revolution of the cranks.

Anything Else?

Rear Tooth Count Hub Required

8 - Cassette (one-piece driver)
9 - Cassette (cog or one-piece driver)
10 - Cassette (cog or one-piece driver)
11 - Cassette (cog or one-piece driver)
12 - Cassette (cog)
13 - Cassette (cog) or Flip/Flop Hub (small side, freewheel) Metric 30mm
14 - Cassette (cog) or Flip/Flop Hub (small side, freewheel) Metric 30mm
15 - Cassette (cog) or Flip/Flop Hub (small side, freewheel) Metric 30mm or Flip/Flop Hub (large side, freewheel) Imperial/American
16 - Cassette (cog) or Flip/Flop Hub (large side, freewheel) Imperial/American

There are no 7-tooth drivers on the market, and there probably never will be; the stress on your chain would be far too high.

There are no 7-tooth drivers on the market, and there probably never will be; the stress on your chain would be far too high.

...What??? He didn't say anything about 7T drivers.

Never mind, you just didn't include that part in your quote.

Yes, because I edited it out, and added in some other things.

Gotcha.

How long is a piece of string? We need more info. How long are your cranks, what gearing do you currently run, and how strong are your legs? I tend to prefer a numerically lower cog, as I've got the leg strength, 180mm cranks, and want to cover the most distance for each revolution of the cranks.

They're 175mm and i have really good leg strength[ im a power lifter doing 335 deadlift and 280 squat] but i still cant get up enough speed!!!!! my gearing is 45 to 16 and i'm gonna run both dirt tires front and back to see if that helps, a specialized spanky up front and shadow belter in back because i recently had an undertone in the back and i didnt get a whole lot of traction but it was still hard to accelerate even on cement. My brakes arent rubbing or anything, and all of my friends have tried riding my bike and they all have trouble accelerating, my bikes 46lbs and back heavy, but i'm not sure of the weight now as for i just got rid of my heavy duty tubes for lighter ones and put lighter tires on also.....well theres alot of info

46lbs! What is it? That's 16lbs heavier than my bike, 21lbs heavier than my race bike. It's even heavier than my tandem. But you should still be able to get it rolling.

His bike is probably 36 pounds, tops. Unless he's still running parts from the late 90s, which I highly doubt.

That bully had some funky 3 piece flatland pegs. A bolt on threaded bit, a collar, then a knurled aluminum peg that threaded on and locked with a small allen screw. Reverse threads for the non-drive side. Light though.

The pegs are Fishbone, almost certainly. And the reverse threads on the non-drive side are for a LHD setup.

I thought that was so they don't unscrew if you grind them, but they don't look like they're made for grinding.

Well, there's a reason for why Fishbone went out of business, and it isn't because their product designs were totally awesome.

You can get Fishbone T shirts on ebay for $2.50. Oh, my cranks say CPL on the back, if I remember right.

The Fishbone shirts on eBay are probably for the band, not the company. I would hope that any Fishbone BMX softgoods would have been burned and trashed by now, anyway; they're not of nearly of as much value as, say, a Poorboy or Play Clothing shirt.

I can't think offhand as to what CPL would stand for. Sorry.

Fishbone the band? Shockingly big-ass freestyle sounds more like the bike.

Yes, that would be the company. They had a very poorly thought-out freestyle frame called the Big Ass, actually, as well an equally bad one named the Ninja. At least the Ninja didn't have thread-on peg bosses built onto the dropouts, though.

Ninja? Oooh, he's riding the black pajamas bike...

No, that would be the Vehicular Cycl... excuse me, I mean the Viet Cong.

I should go lock that now.

[QUOTEHis bike is probably 36 pounds, tops. Unless he's still running parts from the late 90s, which I highly doubt.]

i have an 01 hoffman rythem with all really heavy parts so they will hold my weight...trust me i weighed my bike, my friend weighed his and his was 48, [supra e's]
but he has no problem gettin speed up, and i dont either with his bike

By my estimate, that's about 15lbs unaccounted for.