Gearing

25.4 is converting from mm to inches. Crank lengths are in mm, everything else is inches based.

Is 46x17 gonna be the same as 48x19?

no

48/19 is lower:
**
48/19= 68.21
46/17= 73.5

or thereabouts

**

it's also worth bearing in mind that 46 x 17 requires you BY LAW to wear a dress while riding.

i don't make the rules.

Chris did it really take maths for you to realise that shorter cranks increase gear inches if the ratio stays the same?? I knew that and I don't even know what the + sign means!!

As you obviously do, strange wizard man, can you tell me how many gear inches I'm running with 48x19, on a 23mm 700c tyre, with 170 mm cranks?

The gear inches stays the same. The gear changes though, right?
ie. the rollout is the same length but the effective gear your leg pushes against is smaller/larger depending on crank length. Meh.. i just divide by 27 anyway to annoy Tommy..

http://sheldonbrown.com/gain.html

Gear inches stay the same with shorter cranks. Its gain ratio that changes ( whatever the hell that is ).

For all your http://software.bareknucklebrigade.com/rabbit.applet.html needs

it's also worth bearing in mind that 46 x 17 requires you BY LAW to wear a dress while riding.

i don't make the rules.

haha!

Chris did it really take maths for you to realise that shorter cranks increase gear inches if the ratio stays the same?? I knew that and I don't even know what the + sign means!!

As you obviously do, strange wizard man, can you tell me how many gear inches I'm running with 48x19, on a 23mm 700c tyre, with 170 mm cranks?

As hippy says gi stays the same, it just needs less force to turn longer cranks. same as using a longer handled spanner is easier to turn stubborn track nuts.
(622 + (2 x 23)) / 25.4 x (48 / 19) = 66.4"
(622 + (2 x 23)) / ( 170 x 2 ) x (48 / 19 ) = 4.96 gr

A higher gain ratio means its harder to pedal.

[feigned understanding] ahhhhhhhh... [/feigned understanding]

Is there a big difference between 165 & 170 then? I've found 165 cranks noticably harder to skid even with considerably lower gears than 170.

If I had a singlespeed i'd drop a 56-12 gear and rip it up. Not sure if I'd endorse it though

I'm currently riding a crappy street/hybrid thing running single speed on 44/16. According to the gear calc that's 74,3 gear inches. If I move to a nice fixed gear running 48/17 (that's 76.2 gear inches), is the difference going to be noticeable? I'm guessing I'll benefit from a lighter bike, less traction etc.
Currently the ratio feels about right, in that my speed is good and I don't need to get out of the saddle too much, which is how I like ti ride.

It will be noticeable when you first change because of you being used to riding 44/16. As Chris said, even a difference of 1gi is noticeable when you first change, but you'll quickly get used to it.

I'm thinking of changing my gearing.
When I first built the bike I rode it with a 48/16 gearing and then in search of more speed I dropped a tooth on my cog. I was happy with that until my recent crash and now I'm beginning to think about slowing down a little.

The way I see it is if I had a lower gearing I wouldn't mind stopping for lights more often as it wouldn't be so hard to start up again and my top speed would be lower meaning perhaps next time some c*%t pulls out into my path I wont be doing such a treacherous speed.

I'd also like to learn to skid and trackstand (I fancy playing polo so need to get my skills up to scratch)

So bearing all this in mind, what do you guys/girls think would be a good gearing to try. I was thinking of dropping a few teeth on the chainring (maybe to as low as 42?)

Thoughts...

easier to change the sprocket dude - get an 18t. or if you do change the chainring then 42-16 will work nicely. hope you are healed dude

I have to change my cranks anyway cos they are screwed. My friend has offered me some for free. i just need a chainring.
I do have a 16t sprocket on a set of track tubs but can't be bothered to switch them over really.
Will a 42-15 be alright?
Anyone got a 42t chainring going cheap?

dave, i got a 42t. not sure of the BCD but it is shimano 3/32 - where are you based dude?

gearing is a personal choice. i would still find 42-15 a bit much for me, but then i like to spin more

I'm in Hackney, I work EC1. If neither of those locations suit I will be attending central drinks on Friday (99% sure) and East London polo (again 99% sure)
I'll check the BCD of the cranks I'm getting... Although if it's 3/32 will it be ok with my 15t track cog?

3/32 will work fine with your 15t cog - it relates to the width of the chain
3/32 standard
1/8 track or bmx
i am in hackney as well dude so will pm you my number

Ok, so Jonny's chainring doesn't fit my cranks.

The cranks that I have been donated are a 110 BCD.

Does anyone have a 42t chainring which is 110 BCD???

110 is a bit less common. Try sjs they do a single speed 110 mm bcd chain ring 20 squid I think.

ive been riding a old ss road bike for years before i realised fg even existed and was popular. im cornish, thing take along time to seep down here :) im not too knowledgeable to how gearing ratios work, so bear with me.

i currently ride 52-17, simply because it conviently has a fairly straight chainline. 52-17 isnt a ratio ive seen thrown around on forums much, and cant seem to find any 52t track rings on any sites.

what ratio do you think i go to seeing as this is the gear im comfortable with.

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

Sort you out that will.

52tooth rings are very common.

They are the standard outer ring on double chainset road bikes.

My first Fixed wheel bike ran 52-19 on 27" wheel.

Very nice ratio. 52-17 on 700c is a wee bit higher, imagine its till nice.

If you want chainrings, just type 52t into the cycling section of ebay. Almost all will be rings from doubles, most will be perfect for Single use, just avoid ones with ramps & pins.

Wait, are you saying you run 52/17 in Cornwall?! I've just got back from doing a little cycling down there and the hills you have are fooking mental. Good effort. If it works for you and your comfortable with it use that.