What's this component?

[PunkRock]

I need some help in identifying a component and its purpose on a single speed I may buy. The seller isn't available so I figured somebody here could help.

Given that the bike is a SS, what is the black part hanging where the rear derailleur is normally found? I'm guessing it's purpose is for chain tensioning. Thanks.

http://i298.photobucket.com/albums/mm259/conleyrm/mystery_device.jpg

[CountZero]

It's a Soulcraft Convert chain tensioner:

http://www.soulcraftbikes.com/convert.asp

This part allows you to properly tension the chain on a converted-to-singlespeed hardtail that otherwise lacks chain tension adjustment.

[PunkRock]

It's a Soulcraft Convert chain tensioner:

http://www.soulcraftbikes.com/convert.asp

This part allows you to properly tension the chain on a converted-to-singlespeed hardtail that otherwise lacks chain tension adjustment.Ok, got it. So now I'm wondering why somebody would use it. It seems to me that an easier and cheaper solution would be to either install a shorter chain or remove links from the longer one to get the proper length/tensioned chain. I haven't done a converted-to-singlespeed job so there must be another piece to this puzzle that requires the use of the Convert.

[jvanbrecht]

Thats the actual problem, sometimes removing a single link may make it too tight, and with that link too loose. Thats the point of a chain tensioner, and I believe it also allows for easier gear replacements when you want different ratios, rather then messing with the chain, just adjust the tensioner.

But thats just a guess on my part :)

[jabberwocky]

Because chain links are 1/2" long (and you need to remove two at a time), so the difference between one link is usually too great to work. Thats why singlespeed-specific frames have some sort of adjustment system built in (either a eccentric bottom bracket, sliding dropouts or track ends).

[rciracing]

The chain on a SS stretches easily so the tensioner will also pick up the slack as it stretches.....same way a rear derailleur does on a geared bike. W/ sliding dropouts or EBB, you just adjust accordingly.

[PunkRock]

I appreciate all of the responses.

[eroc]

I think the convert sets to a fixed position, and is not spring loaded like a singulator (or a rear der).

[DKEG]

The Convert is a awesome tensioner. I used one for a while. Easy wheel removal with the push of a button (so to speak). I highly recommend it.

[bunky]

Query: which is better-- a fixed chain tensioner (like the convert) or a springloaded but movable chain tenioner (like the singulator)? Does one provide less slip than the other?

[Cjones]

Are you saying this is a supposed to be "dedicated" singlespeed frame or just a bike that is going to be used as a singlespeed?

If the frame is a "dedicated" singlespeed frame it would have to have an eccentric bottom bracket (since the dropouts are vertical and have a derailleur hanger). And since they are using a Soulcraft Convert I'm guessing it does not.

It is probably a regular frame that has been converted to singlespeed use with the Convert. Without the Convert on there you can't use it as a singlespeed.

[akern2]

The spring loaded design is for, but not restricted to, bikes with vertical drop outs, as well as fully suspended bikes (i've seem 'em run like that).

The only downfall is if you don't have the probably chain length (too much chain), you run the risk of the chain hopping off on rough conditions, or for me, dirt jumps.

The chain pullers are designed to horizontal dropouts. Since those drop outs allow some movement of the wheel towards and away from the bike, you can move the wheel back to tension the chain. I've been seeing these all over the place with BMX bike up here (Frostburg, MD). I have not heard any complaints about the system itself, but have heard the they add insignificant amounts of weight, and can be problematic if you get a flat and don't have the right hex wrench.

[kmax]

I run a singleator that's uses a fixed setting not a spring tensioner. I'm assuming they have both.

The singleator I've got is alright though it released on me the other night during my ride. Probably should just be tightened down before every ride.

That said, it's a temporary solution to a long term "project" for me. Not exactly ideal.