What chainring do I need????
07-04-20, 10:05 AM
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What chainring do I need????
I'm trying to change my front chainring. It's a Shimano and says 50-F on it. I can find a 50-T on Amazon. Will this do? The gears are Shimano Sora 9 speed.
Cheers.
Cheers.
07-04-20, 10:46 AM
#2
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You need to know what the BCD (bolt circle diameter) is of the Shimano Sora crankset (assuming that is what you have). A quick look on Google suggests the BCD is 110 mm. So, many chainrings should be available to fit this crank.
07-04-20, 11:06 AM
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is this your crank?...
SPECIFICATIONS
- Pedal Spindle: 9/16"
- BB Included: No
- Chainring BCD: 74 Shimano Asymmetric , 110 Shimano Asymmetric
- Color: Gray
- Defined Color: Gray
- Crank Intended Use: Road
- Number of Chainrings: Triple
- Crank Length (mm): 170 mm
- Rings: 50/39/30
- Drivetrain Speeds: 9
- Spindle Interface Type: Shimano Hollowtech II
- Chainline/Hub Compatibility: 130 Hubs , 135/142 Road Disc Hubs > 415 mm Chainstay
07-04-20, 12:06 PM
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Nice one, thanks. The BCD is indeed 110mm so I've ordered it. Thanks for your help.
07-04-20, 12:14 PM
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I see absolutely no point in these asymmetrical bolt patterns except to restrict choice of chainrings. Stupid and unnecessary.
07-04-20, 02:14 PM
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I guess we'll never know if the crank I posted is the one in question or not.
Last edited by branko_76; 07-04-20 at 02:29 PM.
07-04-20, 04:07 PM
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Hopefully OP will let us know if what he ordered turns out to be correct. Plenty of ways to go wrong, even if it's Shimano. Fingers crossed
07-05-20, 04:06 AM
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No one mentioned to the op that there is a difference between 5 bolt, 4 bolt symmetric, and 4 bolt asymmetric even if all 3 types have 110bcd.
07-05-20, 06:35 AM
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But this brings up another point for the OP to consider. Besides bold-circle diameter (BCD), mounting bolts must also match what the crank arm will accept.
07-05-20, 06:40 AM
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For indexed shifting systems, they force you to install the rings in the proper orientation for the ramps and pins to be effective in facilitating shifts.
But this brings up another point for the OP to consider. Besides bold-circle diameter (BCD), mounting bolts must also match what the crank arm will accept.
But this brings up another point for the OP to consider. Besides bold-circle diameter (BCD), mounting bolts must also match what the crank arm will accept.
07-05-20, 07:07 AM
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I thought the newer 4 bolt asymmetric chainrings have a little curved tab on one of the flanges to force you into one position only so that it's not possible to install it 180 degrees rotated.
