is anyone running a magic ratio SS for their main commuter rig? I'm tired of my tensioner and was wondering if the myth of chain stretch or other problems have come up for others?

db

Proper semi horizontal dropouts are my magic. There is chain stretch. I replace my chain every spring, and I measure the new against the old, it's at least a half a link to a full link longer after a year.

I should have made it clear that I've got vertical drops on my mountain frame...1/2 to 1 full link would make a big difference...how many miles are you putting on?

db

Why are you opposed to a chain tensioner if you have vertical drops? Chain tensioners are really only a no-no on FG, not SS.

Search for a half-link or 1/2 link. Got rid of the tensioner on my MTB SS by using one of these.

I use the magic gear with vertical dropouts for my SS. What I have found is that anything more than about 1/8" of "stretch" [a misnomer if ever there was one] will allow the chain to drop fairly easily unless it's under load. It takes about 14 months for the chain to be unusable.

When I put the new chain on, it's fairly tight, and offers a bit of resistance to freely spinning. After a few days it's loosened up, and it's good for the next year or so with no complaints. When it's reaching the end of its life, dropping the chain will become more and more common. I might get more life out of it if my chainline was a bit better, but at ~$1/month, I won't complain.

I used to have a frame with horizontal dropouts, and got about 7-8 years out of a chain before it got to that 1/8" of stretch and skipped too much to make it usable.

For example: KMC Half Links @ Amazon - Of course I still don't understand the obsession with magic-gearing a single speed with vertical drops. Yeah, it's cool, I guess. However, it's a load of hassle.

This chart might help you find a gear ratio that will work for you:
https://eehouse.org/fixin/formfmu.php

This is what I was looking for...

Thanks!

I realize that and becasue I have horizontal drops I have no magic gear ratio number to help you. The online calulators should help I suspect.

I put about 3k per year on the SS bike. Maybe it's because I'm a pretty big dude (6'2' - 230) and I mash the pedals hard. I don't know, I just compare them for fun when I swap the chain, and and the stretch is there. It's never an issue because I've got the dropouts to accomodate adjustments for stretch

I used the calculator that MrRamonG posted above on a road bike a few years ago. For what it's worth, it was a fun little project, but in the end it was a bigger pain in the ass (and expense) than just finding a decent frame with horizontal dropouts.

You need one of those White Industries eccentric hubs.

this all started when I was having a lot of skipping issues with my new chain on the way in this morning...I've got the alignment dialed in, and figured I'd try to remove a couple of links to put less pressure on the singleator that I'm running in push down mode...I removed two links at lunch and got the chain so I could just barely get it over the cog and chainring and has very little slack...If I can I'll leave it as it is and just change the chain every 10 months or so...

thanks!

+1

That's what I'll probably do with my beloved Trek 5200 once I get my new race bike built up.

A half-link is 1/2" in length. That's 8 times the suggested distance of "stretch" a chain should have before replacing it! Are you replacing your chainring and freewheel, too? They've gotta be gnawed looking.

Yeah it has been about a 1/2 "(maybe I'm thinking it's a half of a link then) and no , I only replace the freewheels when they break or act funky. Chainrings I swap 2, winter and summer, for ratios, but they work great. It's a single speed. Low maintenance is a big part of the allure.