mazdaspeed

For those of you not familiar with the magic gear, it's basically just using gear sizes to create the proper tension on a singlespeed chain for bikes with vertical dropouts. I ended up with 18/36 which, according to the magic gear calculator deal (also based on the size of my frame and the chain), is "in the green".

What I'm wondering about though, is that if I freewheel it backwards and pull up and over on the chain, I can get it to hook on the other side and come off the gear. I can also do this to my bikes with derailers, but I don't know if it's OK for a singlespeed.

Should I be concerned about this? I haven't ridden the bike yet by the way, it's not done.

EivlEvo

Im not sure I get what ur saying. I ride fixed and ss and there's never a circumstance where I can derail my own chain by flexing the frame or cranks. Im sure it could happen if I imposed a load on it... But it never has.

I also can't do this on my geared bikes.

M_S

Or you could get a ceap chain tensioner, not worry about it, and even be able to choose a gear that fits the type of riding you do instead of havong to accept whatever is "in the gren."

Just a thought.

mazdaspeed

I'm not talking about flexing the frame or cranks, I'm just trying to describe the looseness of the chain. I just don't know if it's too loose for a mountain bike.

mazdaspeed

2:1 is the ratio I wanted anyway, that's not a problem. A tensioner isn't a bad idea but the point of the magic gear is to (use a 2:1 ratio) and use the right gearing (for example 32/16, 36/18, 40/20) to ensure that the chain is roughly the right tension.

I guess what it comes down to is what will happen if the bike is shocked, how loose can the chain be without a major risk of coming off the gears?

croscoe

I know of a guy that went with the magic gear route. I believe his chain stretched to the point of not being usable in 4 months or less. I would invest in a good tensioner, personally.

mazdaspeed

Got any suggestions on small/easy to install ones?

biknbrian

Does chain pop off when you ride it, if not then it's fine.

EivlEvo

I have the one from performance bike ( i think... ,its a surly ripoff)

It works ok... I took it off.

BFG

Surly and DMR both make quality chain tensioners from what I've heard. Please note that's only what I've heard, not experience.

Peek the Geek

Have you considered trying a "Half Link" to tighten up the chain?

Fable

That's what I did. Worked like a charm. You will of course go through chains a bit quicker but I save them until I get a pile then I sell them to a scrap yard for a pittance.

mazdaspeed

That's a good idea as well

mazdaspeed

I guess I'll have to ride it and see. I've been sick all week and it's raining outside so I haven't felt like riding