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What Chain - 3/32 or 1/8?

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What Chain - 3/32 or 1/8?

Old 05-01-21, 06:34 AM
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george_drans
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What Chain - 3/32 or 1/8?

Iím building a bike for the first time, and Iíve got a 5-speed Sunrace freewheel; recommended chain is 3/32Ē. For the crankset, I want to use a 46T BLB single; this recommends a 1/8Ē chain. Are these compatible? If so, what chain should I get?

thanks!
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Old 05-01-21, 07:03 AM
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So the 1/8 chain is for single speed and the 3/32 is for multiple gears.

The 3/32 wonít mesh with the chainring teeth, and the 1/8 wonít flex enough to change gears...it may not even fit between cogs.

You will need to get a chainring that is suitable for a 3/32 chain. Just make sure the bolt circle diameter (BCD) is compatible with your crank.
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Old 05-01-21, 07:26 AM
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manufacturers have produced cycles with five speed derailleur drive trains where the chainwheel and cogs dentition is 1/8"

Regina produced five speed gear blocks with 1/8" cogs

years ago took in a Kmart AllPro bicycle manufactured by Chiorda with this arrangement, it dated from the early 1970's

whether 3/32" or 1/8" all the elements of the drive train need to be on the same page...


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Old 05-01-21, 09:20 AM
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There's no way a 1/8 chain will work on a Sunrace freewheel.

Although there were vintage drivetrain pieces that would, anything Sunrace would have to be mid 90s or newer and of conventional spacing. The other consideration is the rear derailleur. Again, anything made from the 90s on and most everything from the 80s would have too narrow of pulley/cage spacing to accommodate a wider chain.

To the OP, I'd just buy a replacement chainring. I believe that crank uses a 130bcd, so there should be ample options. I don't hesitate to recommend generic chinese-made 1x chainrings. They are mass-produced at a scale that makes them incredibly cheap if you don't pay for a "brand name" label.
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Old 05-01-21, 03:14 PM
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Originally Posted by Dylansbob View Post
There's no way a 1/8 chain will work on a Sunrace freewheel.

Although there were vintage drivetrain pieces that would, anything Sunrace would have to be mid 90s or newer and of conventional spacing. The other consideration is the rear derailleur. Again, anything made from the 90s on and most everything from the 80s would have too narrow of pulley/cage spacing to accommodate a wider chain.

To the OP, I'd just buy a replacement chainring. I believe that crank uses a 130bcd, so there should be ample options. I don't hesitate to recommend generic chinese-made 1x chainrings. They are mass-produced at a scale that makes them incredibly cheap if you don't pay for a "brand name" label.

thanks so much for the info! Iíll have a look around for some narrower chainrings then.

Iíve struggled to find anything 3/32 thatís also got at least 46T. Iíd go down to 44 but I worry that any lower wonít allow the bike to go as quick as I want on the flats. 😂
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Old 05-01-21, 10:43 PM
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Jeff Wills
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Originally Posted by george_drans View Post
Iím building a bike for the first time, and Iíve got a 5-speed Sunrace freewheel; recommended chain is 3/32Ē. For the crankset, I want to use a 46T BLB single; this recommends a 1/8Ē chain. Are these compatible? If so, what chain should I get?

thanks!
If "BLB" means Brick Lane Bikes, then their offerings look like generic single-speed cranks with a 130mm bolt circle diameter. You can use any 130mm BCD, 3/32" width chainring on that crank. Sugino would be my choice:
Universal Cycles -- Sugino Standard Chainrings

The only problem is that you can't get them in kewl colors.
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Old 05-02-21, 06:39 AM
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You definitely want a 3/32" chain for the 5-speed freewheel. Try it with your "1/8"" chainring. If the inside links of the chain fall smoothly over the teeth of the chainring, it will work fine. If they hang at all, you will indeed need a chainring with a narrow tooth profile.

(For what it's worth, I did once own a 14-16-18-20 cog block in a 12-speed hybrid conversion kit, which also included an extended-length axle for a standard 3-speed wide-ratio Sturmey Archer hub. Those took a 1/8" chain, but, as mentioned in an earlier post, 3/32" took over multispeed applications decades ago.)
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