kingtubby

i want to build myself a fixie/ss but am new to this. i found a decent frame, but it has vertical dropouts on the back. how much of a problem will this be as far as chain tension, etc?

thanks!

stephenhatesyou

sheldonbrown.com

eno hub
etc etc

Seggybop

it will work if you are ok with other than the exact gear combination you plan for. you will need to try some different combinations to find one that has good tension. if that's not acceptable, you can buy the ENO hub, but it's horribly expensive.

carleton

...and which part of that is good news?

A "Golden Ratio" is terribly hard to find. And if you don't have several chainrings and cogs at your disposal. Even harder.

Dude, just try to find track/fixie frame.

kingtubby

word. the thing about this frame is that it's cheap. track frames are 5x more expensive, at least, on ebay. i'll keep looking around though... just want a project to work on. thanks for the help, everyone.

prodigal son

look at local Bike co ops or police auctions

moki

a half link (made by KMC, I think) may be the ticket.

Seggybop

Not really. Have you tried it much? The easiest way to find one is to put on a wheel with a gear cluster (that's so hard to come across) and try combos until you find a good one. A half-link, about a dollar from the local hardware store, will make this significantly easier. Once you find a good combination acquire the fixed cog in that size.

ISeeDeadHuffies

I'm surprised noone mentioned this.

https://www.peak.org/~fixin/personal/fmu/php/fixmeup.php

braingel

i'm converting a newer mountain bike with vertical dropouts to a singlespeed, and i bought a chain tensioner. it's not as nice as not having one, but for the work it would take to find the right ratio i figured i would just use it. i got it for $1 on ebay(that was weird). that fixmeup website looks nice though...i might just do that now.

carleton

Yeah, I tried it back in 2002 when I converted a Aluminum Trek 1000 to SS. I was working at a bike shop at the time with access to lot of parts and even then it was a frustrating experience. I finally got it working, but:
1) my ratio was like 52/16
and
2) I vowed to never try it again.

Oh yeah, when you are working on a Golden Ratio, once you find it...that's it. You are pretty much stuck in that gear combo whether you are comfy with it or not...like my 52/16.

donkekus

Carleton, though I am too tired to really explain it more in depth I can assure you that a magic, or golden ratio, and your 52x16 could have been altered easily. I forget exactly how off the top of my head, but it is possible.

Something along the lines of:

40x18 = 42x16...

carleton

Agreed.

But, for each chainstay length, you get 2 maybe 3 magic ratios which are about 8 gear inches apart. And if I ever wanted to adjust to one of the other gear inches, I'd have to have/buy a cog *AND* a chainring. A problem easily solved by a rear-facing and (to a good extent) a horizontal dropout where you can change the rear cog from like 14-19t to your taste.

I'm not saying someone shouldn't do it. Just know what you are getting into.

sivat

If you want to go single speed, you can just get a chain tensioner. If you want to go fixed, thats when it gets harder.

LóFarkas

Not desperately hard to build a vertical-drop fixed, just keep in mind two things 1)it is a hack 2)it is a hack.
Not too hard at all to find a magic ratio. Have a half link and a couple of rings and cogs handy and try them out, or try one of the online calculators. They may even work, who knows?
Be prepared that the chain will stretch... then you need to find a game plan. Mine was to pick up a file and attack both the dropout and the axle. Did I tell you it is a hack?

shogun17

I just built myself a singlespeed/fixie MTB out of a GT avalanche. Golden Ratio, 42/18 or with flattened axles 42/17 as well.

Aeroplane

Ló is the king of the make-it-work bicycle. If you really want a project, not just a bike kit, it can be done. But be prepared for frustration.

LóFarkas

That title belongs to Sheldon, but I'm trying to do my best, too

dirtyphotons

the online magic gear calculator works perfectly. measure carefully (center of bb to center of axle) and you'll get it right on the first try.

however, your chain will stretch over time and you will either need to deal with the slack or replace your chain often.

it's even more advisable than normal to have a brake on there if you're running a magic gear.

Analog

You know, if it's not that great of a frame to begin with, you only need something like 1/2" of movement in the dropouts. A rat-tail file or jeweler's saw both work wonders, and half-links are cheap.
I've done it before, and never had any problems. Just don't take away any more material than you absolutely need to.

[edit] Sheldon also proposes filing down two sides of your axle, but I'd rather keep the axle whole, and file the dropouts.

LóFarkas

You don't need 1/2". With an optional half link, only 1/4" is enough to make any ratio work. And if you're willing to drop or add 1 tooth in the front as the situation requires, then even less. (1 tooth will be <2 gear inch change... I doubt that you'll notice)
Again, it's preferable to find a setup where you're at the front of the dropout w/ new chain.