fixed gear ratios

cmyk

Hey,

Can anyone help me with understanding gearing and ratios? I have googled for it but seems some american sites deal in inches and some in teeth?

Sheldon browns site seems to ask for info I'm not sure of to work out another system?

Basically I think I have 48:16 (teeth?) at the moment, loving the bike but prob a bit tough on the bigger hills for me yet. Also would any decent shop be able to swap it out for me? or can anyone recommend shops that deal with fixed gears?

penexpers

48:16 is the ratio of teeth at the front to teeth at the back. I think it roughly means that one turn of the front cog will move the rear cog three times.

mtbdude74

Hi CMYK, glad to hear that you're getting on ok with the Pista. The original rear hub is a flip flop, so all you have to do is get a new single cog (either fixed or a freewheel) and screw it on. I've an 18 on the flip side and it is fine with most hills in the city center. Getting home (half way up the Dub mountains) on a windy day though is another story!!!!!!! Cycleways do BMX singlespeed freewheels which will fit. Alternatively check out "CharlieTheBikeMonger" on ebay.uk.

niceonetom

i find gear inches the easiest way to compare ratios and this is a nice simple calculator to compare. sheldon brown (pbuh) is sometimes a bit ott on the info supplied/needed, though it's always accurate.

what's your bike? most seem to come 42x16 as stock which gives about 70 gear inches. 48x16 gives 81, which might be a bit much for you. i ride 48x17 (76 g.i.), which is a good compromise for me but i prefer to grind up hills than spin on the flat. if you go to 48x18 (72 g.i.) you'll be fine.

i've never brought my fixie to a shop as they really are simple enough that you should be able to do any maintenance yourself. changing cogs is no problem - all you need is a lockring tool and a chainwhip. some of this has been dealt with recently here. i've found getting cogs the right size to be tricky in dublin but that's because 17 seems to be a bit unusual. cycleways do surly and shimano. i think cycleogical do to.

make sure you get the right width cog too, 1/8 or 3/32. it should be written on the cog you have at the moment.

cmyk

Great stuff guys, it's a stock bianchi pista at the moment and im pretty sure as standard its 48:16. Don't get me wrong, I love riding it and haven't been back on my other bike since getting it but just something that would suit me better would top it off.

Would going to a 17tooth make much of a difference?

I'd rather have more control over the bike than the ability to reach breakneck speeds on the flat yet.

Also at my ratio I don't know how people seem to be able to 'lock' up their legs with apparent ease without brakes. (or maybe my legs are just weak:()

fish-head

Do you have a brake on your bike?

penexpers

The Pista doesn't come with a brake as standard, so probably not.

niceonetom

fish-head wrote: »

Do you have a brake on your bike?

+1. i'm sorry to say but i'm see more and more posers out there. no brakes is fine if you're super compentent with the skids and hops, but for the rest of us it's lunacy and bravado. function > style.

going to 17 won't make a huge difference but it might be enough. i'd recommend 18 until you've built up a bit. each to their own though. go out on your geared bike and find out how much one tooth changes things. use the calculator to figure out where you should be on the castette.

ratios do effect how hard it is to skid but it's really about technique rather than pure strength. commit to it.

cmyk

fish-head wrote: »

Do you have a brake on your bike?

I have a front brake yep, I do not have a death wish. I just meant that there is no way I could stop the bike with just my legs as some can. ie the end of this vid http://youtube.com/watch?v=pYWhJCzOh7Y and that maybe its the lack of power/technique or the ratios? I would never get rid of my brake but would like to have some of the control those messengers etc have over their bikes.

Don't get me wrong my main reason for wanting to get an easier ratio are the hills. I commute from ranelagh to dun laoghaire so its up the stillorgan dual carriageway most of the way and though it doesn't look steep with those ratios it burns.

niceonetom

cmyk wrote: »

http://youtube.com/watch?v=pYWhJCzOh7Y

wow. androgyny.

cmyk wrote: »

I would never get rid of my brake.

me neither. and i can skid like a legend :cool: . a brake makes me go faster. as i say, commit to locking the wheel, if your tentative you'll fail. the key is to unload the back wheel for a second - it's virtually impossible to do with your ass on the saddle so, hop forward on the bike and give a tug up with your front foot and stamp down with your back foot. it'll come, and once you get it once it'll get easier and more intuitive. just remember not to try it when you get back on a freewheeled bike. seriously.

you do use clips or cleats right? it can't really be done on flat pedals unless you use a tiny gear.

cmyk

niceonetom wrote: »

wow. androgyny.

Indeed, I wasn't sure whether I was just missing the earrings!?

Hmmmn, it all sounds very easy and straightforwards when you write it down.
Time to 'man' up about it then.

Though I might try it in carpark when its wet first?

niceonetom

cmyk wrote: »

Indeed, I wasn't sure whether I was just missing the earrings!?

Hmmmn, it all sounds very easy and straightforwards when you write it down.
Time to 'man' up about it then.

Though I might try it in carpark when its wet first?

try it on wet grass. get the feel for it. it's one of those things that are simple, but not easy.

cmyk

Will do, cheers for all the advice. Will look into the 18t rear too.

fish-head

I first got the hang of doing long skids one evening on smooth tarmac after it had rained, after that it got easier as I got more confident. You're running a pretty high gear for that kind of tomfoolery.

I have an 18t EAI 1/8 cog, totally new, if you'd like to take it off my hands. That'd give you around 70 gear inches which is the best of both worlds.

Equally bad for both the flat and the hills!

cmyk

Sounds good fishhead, out of the office now until after lunch or so ill drop you a pm then, Im not sure of the width though, had a quick look last night but didnt see any indications? Would anyone be kind enough to help show me how to fit it also if I came to them?