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Old 03-12-08, 10:33 PM   #1
mazdaspeed
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Singlespeed crew: chain tension? (noob question time)

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.
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Old 03-12-08, 11:49 PM   #2
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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.
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Old 03-13-08, 12:00 AM   #3
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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.
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Old 03-13-08, 12:21 AM   #4
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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.
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.
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Old 03-13-08, 12:27 AM   #5
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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.
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?
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Old 03-13-08, 12:58 AM   #6
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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.
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Old 03-13-08, 01:00 AM   #7
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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.
Got any suggestions on small/easy to install ones?
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Old 03-13-08, 06:51 AM   #8
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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.
Does chain pop off when you ride it, if not then it's fine.
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Old 03-13-08, 08:26 AM   #9
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Got any suggestions on small/easy to install ones?
I have the one from performance bike ( i think... ,its a surly ripoff)

It works ok... I took it off.
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Old 03-13-08, 08:40 AM   #10
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Surly and DMR both make quality chain tensioners from what I've heard. Please note that's only what I've heard, not experience.
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Old 03-13-08, 11:03 AM   #11
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Have you considered trying a "Half Link" to tighten up the chain?

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Old 03-13-08, 12:46 PM   #12
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Have you considered trying a "Half Link" to tighten up the chain?

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.
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Old 03-13-08, 02:30 PM   #13
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Have you considered trying a "Half Link" to tighten up the chain?

That's a good idea as well
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Old 03-13-08, 02:30 PM   #14
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Does chain pop off when you ride it, if not then it's fine.
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
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