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Old 04-22-07, 08:45 PM   #1
Altinos
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Biopace SG cranks.

I just picked up a Schwinn Woodlands with Biopace SG cranks on it. I'm cannibalizing it for parts. When I went to remove the cranks, I discovered that they were bolts instead of nuts, and I couldn't get my Park crank removal tool to work. I didn't force it, though. The threads fit. Does this require a special tool, or do I just need to give it some WD40 or other stuff and push harder?
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Old 04-22-07, 08:58 PM   #2
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Quote:
Originally Posted by Altinos
I just picked up a Schwinn Woodlands with Biopace SG cranks on it. I'm cannibalizing it for parts. When I went to remove the cranks, I discovered that they were bolts instead of nuts, and I couldn't get my Park crank removal tool to work. I didn't force it, though. The threads fit. Does this require a special tool, or do I just need to give it some WD40 or other stuff and push harder?
Most better quality bottom brackets use bolts, not nuts. On older ones, they often needed a 15 mm socket, newer ones used a 14 mm socket. More recent stuff uses an 8 mm Allen wrench.

The bolts are generally all interchangeable.

By the way, there's no such thing as a "Biopace crank." It's the chainrings that are Biopace.

See: http://sheldonbrown.com/biopace

Sheldon "Bolts" Brown
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Old 04-22-07, 09:05 PM   #3
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Quote:
Originally Posted by Sheldon Brown
Most better quality bottom brackets use bolts, not nuts. On older ones, they often needed a 15 mm socket, newer ones used a 14 mm socket. More recent stuff uses an 8 mm Allen wrench.

The bolts are generally all interchangeable.

By the way, there's no such thing as a "Biopace crank." It's the chainrings that are Biopace.

See: http://sheldonbrown.com/biopace

Sheldon "Bolts" Brown
I say Biopace crank because it doesn't appear that I can remove the chainrings from the crank, looks like they're riveted.

The crankarms are also plastic, which is something I'm not used to. I was able to get the bolts off with a 14mm socket.
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Old 04-23-07, 07:13 AM   #4
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Make sure that the washer is removed along with the bolt.
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Old 04-23-07, 07:41 AM   #5
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Quote:
Originally Posted by Altinos
The crankarms are also plastic.
!!!!!!

Hope not
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Old 04-23-07, 07:50 AM   #6
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The crankarms are metal (probably steel) with a plastic cover. This is probably what you're looking at:

I got this crank off of an old Diamondback mtb, and then used it on this build for a friend.

Anyway, cheaper bottom bracket spindles had threads sticking out of the end, and used a nut to tighten the crank onto the BB spindle, instead of having a hole for a bolt to do the job instead, as do most (and all better) bottom brackets.

However, your standard crank remover tool will work on this sort of bottom bracket as well.
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Old 04-23-07, 08:17 AM   #7
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Quote:
Originally Posted by Altinos
I say Biopace crank because it doesn't appear that I can remove the chainrings from the crank, looks like they're riveted.
Correct.
Quote:
Originally Posted by Altinos
The crankarms are also plastic, which is something I'm not used to. I was able to get the bolts off with a 14mm socket.
Plastic coating over Alloy. The aluminum/magnesium alloy used is very prone to corrosion. Be careful not to scratch or puncture that plastic coating. Doing that will not damage it but it will start looking really ugly when exposed to air. It's sort of like rust on steel.
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Old 04-23-07, 08:23 AM   #8
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Quote:
Originally Posted by n4zou
Plastic coating over Alloy. The aluminum/magnesium alloy used is very prone to corrosion. Be careful not to scratch or puncture that plastic coating. Doing that will not damage it but it will start looking really ugly when exposed to air. It's sort of like rust on steel.
If he's got the cranks that I had (pictured above), then it's steel underneath the plastic - it attracted a magnet pretty obviously.
I don't see any reason that they would use an aluminum/magnesium alloy on a low-end crank.
What cranks did they do this with, and when? I'm curious.
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Old 04-25-07, 10:12 PM   #9
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Quote:
Originally Posted by Noam Zane
Make sure that the washer is removed along with the bolt.
D'oh! That was it. Thanks!
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Old 04-25-07, 10:13 PM   #10
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Originally Posted by jgedwa
!!!!!!

Hope not
Yes, they do appear to be plastic coated metal.
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Old 04-26-07, 07:36 AM   #11
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Quote:
Originally Posted by timcupery
If he's got the cranks that I had (pictured above), then it's steel underneath the plastic - it attracted a magnet pretty obviously.
I don't see any reason that they would use an aluminum/magnesium alloy on a low-end crank.
What cranks did they do this with, and when? I'm curious.
Alloy from recycled engine and transmission blocks. If the manufacturer uses recycled material for the production of parts where a good finish is required the parts will be painted with a high quality epoxy paint, power coated, or lowest cost option dip coated in plastic. They also plastic coat steel to hid it's use.
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Old 04-26-07, 07:48 AM   #12
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Cranks that look like that that i've seen have always been steel encased in plastic. I imagine if they were alloy with an additional plastic casing, they would be somewhat bulkier anyway.
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Old 04-26-07, 07:50 AM   #13
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Hello All:

I have two Schwinn Woodlands, that I have made
fowl weather commuters out of them. They are great,
for snow, rain. I had to replace the crank on one,after it
fell over and bent the chainwheel. I used a Nasbar triple
crank, it just bolted right on to the bottom braket. I
belive it was about $25. I have had the one bike since it
was new in 1991. Someone gave me the other one.I added
fenders, rack and lights, and use it in the winter,and on wet days.
It is a good soild bike,and will not let you down.
Just don't drop it on the chainwheels that aren't the strongest.
Hope you enjoy your Woodlands.
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Old 04-26-07, 08:36 AM   #14
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Quote:
Originally Posted by n4zou
Alloy from recycled engine and transmission blocks. If the manufacturer uses recycled material for the production of parts where a good finish is required the parts will be painted with a high quality epoxy paint, power coated, or lowest cost option dip coated in plastic. They also plastic coat steel to hid it's use.
Interesting, that makes sense. Thanks.

Quote:
Originally Posted by robo
Cranks that look like that that i've seen have always been steel encased in plastic. I imagine if they were alloy with an additional plastic casing, they would be somewhat bulkier anyway.
Good point - although old-school aluminum cranks were pretty svelte (and probably flexy). See this picture (what's not on my fixie). But those were still thicker profile (as viewed from above) than steel underneath the plastic in your cranks would be, so point stands.
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Old 04-26-07, 09:28 AM   #15
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Quote:
Originally Posted by timcupery
If he's got the cranks that I had (pictured above), then it's steel underneath the plastic - it attracted a magnet pretty obviously.
I don't see any reason that they would use an aluminum/magnesium alloy on a low-end crank.
What cranks did they do this with, and when? I'm curious.
Those are the exact cranks I have.
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Old 04-26-07, 09:30 AM   #16
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Quote:
Originally Posted by Bikehead
Hello All:

I have two Schwinn Woodlands, that I have made
fowl weather commuters out of them. They are great,
for snow, rain. I had to replace the crank on one,after it
fell over and bent the chainwheel. I used a Nasbar triple
crank, it just bolted right on to the bottom braket. I
belive it was about $25. I have had the one bike since it
was new in 1991. Someone gave me the other one.I added
fenders, rack and lights, and use it in the winter,and on wet days.
It is a good soild bike,and will not let you down.
Just don't drop it on the chainwheels that aren't the strongest.
Hope you enjoy your Woodlands.
I needed the parts for a Nashbar MTB frame that I just got in my size. The Woodlands is a woman's frame and far too small for me, although the cranks were 170mm. I'm just taking the parts off and will probably sell the frame.
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