Single speed crank upgrade advice needed

[SkyRider]

I'm in the process of upgrading a cheap single speed pick up as a campus bike a few years back to be something more fun. I have discovered that the bike has an American style thread-less bottom bracket shell. In order to have more options in cranks I am going to use an adapter for a 68mm square taper. My question is has anyone done this before, if so which adapter did you use and how much width did it add to the bottom bracket shell?


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[oldpotatoe]

I'm in the process of upgrading a cheap single speed pick up as a campus bike a few years back to be something more fun. I have discovered that the bike has an American style thread-less bottom bracket shell. In order to have more options in cranks I am going to use an adapter for a 68mm square taper. My question is has anyone done this before, if so which adapter did you use and how much width did it add to the bottom bracket shell?


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Astabula crank, gotta take the cups out. New adapter cups no wider, put in, screw in BSC BB, appropriate crank and bob's yer uncle. If the crank has a 107 or 110 option, spindle length, use the 110mm.

[SkyRider]

Astabula crank, gotta take the cups out. New adapter cups no wider, put in, screw in BSC BB, appropriate crank and bob's yer uncle. If the crank has a 107 or 110 option, spindle length, use the 110mm.

I just looked up the astabula cranks. Not quite what I'm looking for. Thanks for the tip though. I really want to stick with the plan of a square taper bottom bracket and a five bolt crank.


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[PacNW2Ford]

He's trying to tell you how to do what you want to do...

[SkyRider]

He's trying to tell you how to do what you want to do...

Then I'm failing at my use of the google machine. The picture I found was of a crank pretty much identical (granted of a higher quality) to what is on the bike now. Can one of you post a link so I can see what you are referring too.


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[Bruce K]

I think he's trying use a more "traditional" 5 arm spider type crank

BK

[JWDR]

You want something like this

http://www.wrenchscience.com/mountain/bottom+brackets/Truvativ/BMX+to+Threaded+BSA+BB+Adapter/2012/

if I understand you correctly.

I have no experience using one though, seemed like too much work for not enough gain. I ended up just buying nicer cranks for my bmx.

[SkyRider]

You want something like this

http://www.wrenchscience.com/mountain/bottom+brackets/Truvativ/BMX+to+Threaded+BSA+BB+Adapter/2012/

if I understand you correctly.

I have no experience using one though, seemed like too much work for not enough gain. I ended up just buying nicer cranks for my bmx.

Saw this on amazon as well. This is what I had in mind. Being a single speed road setup, I think it's worth the $20. I'm just hesitant to order a bottom bracket until I'm sure what size it's going to end up being.


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[oldpotatoe]

I just looked up the astabula cranks. Not quite what I'm looking for. Thanks for the tip though. I really want to stick with the plan of a square taper bottom bracket and a five bolt crank.


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What you have is Ashtabula crank/bb cups, big silver cups, take them out(tap), insert BB adapter as have been mentioned, screw in BB for selected crank, install crank, fixed or SS wheel, go ride. If this is a mystery, go to good bike shop, ask them.

[Bruce K]

Guys

I think the question he keeps asking is if he uses that adapter and wants to use a square taper bottom bracket, is there anything special about the bb that he needs - spacers, special length/ model, etc ?

BK

[EricEstlund]

That was already answerd above, but I can see how it might have been missed. In general, these adapters don't make the shell with any wider, and you just thread in the same BB width you would for the given crank set.

[SkyRider]

That was already answerd above, but I can see how it might have been missed. In general, these adapters don't make the shell with any wider, and you just thread in the same BB width you would for the given crank set.

Thanks for the direct answer. I was just a bit unsure about that. It's hard to tell from pictures if you end up with a few extra mm of bb shell.


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[EricEstlund]

From the internet:

http://i32.photobucket.com/albums/d7/k4drd/Bicycles/1973%20Super%20Sport%20CJ809208/CIMG5638med.jpg

You can see how the adapter is relieved to allow BSA BB to sit in the same relative position as it would in a smaller shell.

[SkyRider]

From the internet:

http://i32.photobucket.com/albums/d7/k4drd/Bicycles/1973%20Super%20Sport%20CJ809208/CIMG5638med.jpg

You can see how the adapter is relieved to allow BSA BB to sit in the same relative position as it would in a smaller shell.

Perfect thanks. Off to amazon to order parts.


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[oldpotatoe]

Guys

I think the question he keeps asking is if he uses that adapter and wants to use a square taper bottom bracket, is there anything special about the bb that he needs - spacers, special length/ model, etc ?

BK

"New adapter cups no wider, put in, screw in BSC BB, appropriate crank and bob's yer uncle. If the crank has a 107 or 110 option, spindle length, use the 110mm."

echo in here?

[Bruce K]

Lost in the discussion about the fancy crankset

BK