help with front chain ring purchase - How large can I go?... and still be practicle?
 

I just bought a used Bianchi Campione D'Italia set up as a single speed. It hasn't arrived yet but I already know I want to enlarge the front chain ring. How large can I go? I think it's 18 in the back.

I live in the Portland Maine area and have been commuting solely by bike since June. It's nearly all flat land around here and so I thought I'd like to gear the bike somewhat high. How big can I go on the front?

thanks, jack

I live in a relatively flat ground area as well. It's honestly all about what feels good for you. try different things out. I personally run a 49X13 for my higher ratio and on days when i wanna chill i flip my wheel to the 16T cog.

I haven't gone any larger than a standard modern road chainring, 53t with a 16t and 17t cog. Accelerating from stops takes some technique, but can be done to get some nice jack rabbit starts if your legs are strong enough.

These days I'm planning on dropping to a custom 50t track chainring with a 16t cog on my Switch and a 53t with a 17t cog on my Leader, both roughly 82 GI.

EDIT: Holy high gear Batman! 49x13 is 102 GI, that's pretty huge from the streets Bro.

I have been using a 50 and 52 for some time only because I sold my 48t and don't care the change the rings on the road cranks I have. Paired with a 21, 20, 19, 18, or 16 tooth cog.

Leg day all day, everyday. I use to work my legs out allot for wrestling so the higher gear doesn't bother me.

102gi for street....

I ran a 49x16 for a recent ride on the coast, my knees weren't happy but I'm an old man with a decrepit body. You can go as large as you'd like but youll need to run a bigger cog on the rear to compensate.

if you just want a big ring up front just cause i'd say do 52 x 19

50+ chainring up front is fine if you wanna roll one pant leg up to yer knee like a 90's crack dealer. I'd go the other way, with a 44 or so, and try different cogs in the back.

Old man ? That's hilarious !

Thats.....Creeeepy

In theory, the less a chain has to flex when bending around a chainring or cog, the slower it will wear. So if drivetrain wear is a prime concern, you'd want to use the largest chainring you can fit, and then size your cog accordingly to get the gearing you want. Since my fixed-gear is a converted MTB, I don't have as much clearance for a big chainring ~42mm away from the centerline as one would have on a track or road bike, so I make do with a 45T.

I'm running 42-15 on my bike. That's about average gearing. Plenty fast but not so high I can't get up hills.

You say you haven't gotten the bike in yet but you KNOW you want to make it bigger. Compensating perhaps?

check this gear calculator out: Sheldon Brown's Bicycle Gear Calculator

49x17

how is this the one reasonable post in here?

Tony Martin over here trolling around on a 57 ring.

I have spent some time in Portland, ME. You will be fine all the way up with a 56 running an 18 rear. Just be careful, when you get that big some rings go to aluminum and those wear way faster. Don't try and bike up to Camden with that ratio though, unless you have robo legs, that hill will massacre you.

I droped to 48/12 for better acceleration out of lights where I moved to now BTW, still flat, just WAAAAAAYYYYY more traffic.

wut

+1

lulz.

yea... typo... not acceleration... top speed. My bad yo. :crash:

I misspell speed as acceleration all the time too :rolleyes:

http://i.gyazo.com/aeaedb7f74a76b81a260f6bb6cf3b68b.png

>2014
>mfwwatchoutforaluminumchainrings
>mfw48x12lighttolight

lulz.

It will make you a better cyclist if you ask the opposite question:

"How low can I go?... and still be practical?"