Gear inch/ratio question

Just over 200 rpm I think. I've seen 200 rpm whilst on one of those horrible gym bikes with wide pedals and cranks.

Should I try roller racing?

More than bloody 200rpm! Would love to see your legs doing that. Impressive..

I've never ridden fixed before so instinctively I though it better to ride a LOWER ratio fixed. Sheldon Brown (http://sheldonbrown.com/fixed-conversion.html) suggests the opposite, however I wouldn't be riding fixed most of the time (as SB hopes).

I had planned to run 49/17 free and 49/ 18 fixed. Should I go 49/16 fixed?
GR of 3+ seems a bit scary for first time fixed, I thought a lower ratio would help me keep the speed down (have a habit of running into/ along traffic a bit fast).

1. is that brakeless, or flip flop with brakes as the third sentence suggests?
   
2. are you cycling in London?
   
3. 49x18 is a good ratio.
   

1. No-way, flip-flop with front and rear.
   
2. Yes - a major fear of fixed is curb-strike and ground strike when cornering (170mm crank length).
   
3. Glad to hear.
   

1. Yes - a major fear of fixed is curb-strike and ground strike when cornering
   
   

Never had pedal strike on the road on my trackbike, using 170mm cranks and SPD-R pedals. Not in London though.

ok how can i use this calculator to find out the 'magic gear' ? its the chain stay + length of chain + chain ring + rear cog combo isnt it .. What I am presuming is I will have to alter the chainring/cog numbers to match my chain stay length ..

^ Don't know if these have been mentioned, but I've found them both useful.

Magic gear calculator.

http://www.eehouse.org/fixin/formfmu.php

Other useful stuff.

http://software.bareknucklebrigade.com/rabbit.applet.html

^ Don't know if these have been mentioned, but I've found them both useful.

And after scanning this thread, I see I'm not alone :-0

Hi All,

Without wanting to get into sheldon brown's calculator shenanigans. Could someone explain to a newbie what a decent ratio would be. I have a Sprocket (rear) 18 T and I'm thinking of getting a 46 T 170mm chain wheel set. Wheels are 27 x 1 1/4.

Majority of terrain will be flat with the exception of two low gradient hills. Just want it for cruising really, not racing etc.

Any help (not sarcasm) would be greatly appreciated.

46:18 sounds fine. On the spinny side for my taste. But a nice ratio none the less. You'll really just have to try it.

Eithre way a 46 t chainring is a nice size for general road use.

46:18 sounds fine. On the spinny side for my taste. But a nice ratio none the less. You'll really just have to try it.

Eithre way a 46 t chainring is a nice size for general road use.

Cheers buddy. Sorry to sound like a total novice but what does spinny mean?

Spinny = exhausting for the non-cardio peeps.

47/17 is the way

thinking of going 48 or 50 maybe

46 / 18 is 68.4 gear inches according to my calculator app thingy and anything between 65 and 75 is generally good in my opinion. It's easier to skid on the lower GI gearings, but you can't hit the same top speed.

Thanks fellas.

and 'skid' ?

Ask Mr miyagi

47/18 for skid patches

Cheers buddy. Sorry to sound like a total novice but what does spinny mean?

Means you have to spin the cranks fast to cruise at a nice pace. Not something I'm good at. But thats me. Its pretty much in the middle of the range most folk use. With the 46T chainring allowing for a lot of adustment either way by swapping cogs. It sounds like a nice starting point.

It's all a bit subjective, isn't it. If I'm just riding along, >115rpm feels 'spinny', and if I'm sprinting or winging it down hill, then >175rpm feels 'spinny'; but I could just as easily ride 25 miles in 53x12 or whatever, and then switch to a medium gear and anything >60rpm would feel spinny for a bit.

It's a shit descriptor. That's what I'm getting at.

Hi all,

So I have recently purchased a schwinn cutter which I have been riding religiously. However it has a 46x18t drivetrain which is starting to feel a bit to easy to ride. I cant get speed up without peddling like a man possessed. So im thinking about changing to a 16t cog. Will this make a lot of difference and how would I go about doing this? (Apologies for my complete lack of knowledge)

So, this boils down to ratios. This is the relationship between the number of turns of the big cog and the corresponding turns of the small cog which in then turns the back wheel.

At present one turn gives 2.5 turns of the back wheel. Changing to 16 teeth will give 2.875 turns of the rear wheel.

More turns of the back wheel = harder to pedal up hills.

I ride 54/14 in hilly Edinburgh. Harder to get up a hill but less spinning like a madman when I go back down them.

Changing a cog is a doddle.

You will need a lock ring tool and a chain whip. ( I use the one bought from here from here http://www.lfgss.com/thread101643.html). Its fecking great

Take off the back wheel, use the lock ring tool to remove it with a twist, it should then unscrew.

Use the chain whip to loop the chain part around the cog and use leverage. Try not to skin your knuckles.

Carefully replace with the new shiny cog you've procured. Grease the threads with something appropriate and carefully screw it on. Tighten with the tool.

Carefully replace the lock ring and tighten.

Replace back wheel with correct chain tension and you're good to go.

This will have been covered elsewhere but its sunny outside and life is good so this might be nicer than stating UTFS.

:)

Thank you so much. Didnt even mean to post it in this thread. Must of done it automatically when I put in the thread title. However extremely grateful. Thanks alot.

2 teeth at the rear is huge.
http://www.machars.net/bikecalc.htm

not going to tell anyone what gear to ride but want to flag the spinning like a madman comment for anyone reading your guys posts with no direct experience:
at 50kmph cadence is 100. hardly spinning like a madman.

Didnt even mean to post it in this thread. Must of done it automatically when I put in the thread title.

It was probably merged by a moderator. They're not quite automatic yet. :)

I ride 54/14 in hilly Edinburgh. Harder to get up a hill but less spinning like a madman when I go back down them.

100+ gear inches around Edinburgh. Mash away my man, mash away.

Hoy Q&A in 2006

"If it's not a trade secret, what gears do you ride?"

"For the Kilometre it's virtually always 51 x 14, maybe a little lower for a big, old outdoor track, maybe a little higher at altitude. In the team sprint it's 51 x 14 and for the individual sprint 50 x 14."