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Chain sizing technique for a 10 speed triple crank.

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Chain sizing technique for a 10 speed triple crank.

Old 12-25-20, 11:17 PM
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Ev0lutionz
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Chain sizing technique for a 10 speed triple crank.

Do I use the Big Big method on Park tool or small small through the derailleur ? An experienced bike mechanic told me the small small method is more accurate though.
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Old 12-25-20, 11:18 PM
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Big:Big is safest.
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Old 12-25-20, 11:26 PM
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Originally Posted by Bill Kapaun View Post
Big:Big is safest.
So I have to add 2 links yeah and bypass the derauileur ?
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Old 12-25-20, 11:31 PM
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You don't "have" to do anything, but that's the way I usually do it.
I may even add a bit more if there's a possibility I'll use a larger cassette.
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Old 12-26-20, 01:04 AM
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Originally Posted by Ev0lutionz View Post
Do I use the Big Big method on Park tool or small small through the derailleur ? An experienced bike mechanic told me the small small method is more accurate though.
"More accurate" to what? Each method is pretty accurate at gauging a specific phenomenon: small-small makes your chain as long as possible without going slack in the small-small, while big-big makes your chain as short as possible without ripping the derailleur off the bike in big-big.
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Old 12-26-20, 06:30 AM
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Originally Posted by HTupolev View Post
"More accurate" to what? Each method is pretty accurate at gauging a specific phenomenon: small-small makes your chain as long as possible without going slack in the small-small, while big-big makes your chain as short as possible without ripping the derailleur off the bike in big-big.
A slack chain is probably preferable to ripping off a RD I'd like to think.
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Old 12-26-20, 07:49 AM
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Originally Posted by dedhed View Post
A slack chain is probably preferable to ripping off a RD I'd like to think.
That's my feeling, too. Some will say, just don't crosschain but that doesn't mean it doesn't happen occasionally.
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Old 12-26-20, 08:33 AM
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Either method is works as long as you stay within the rear derailleur wrap capacity. If you exceed that then big-big is much safer and small-small will give you a slack chain.

I usually modify standard Shimano road triples from 50/39/30 to 50/39/26 and, with a 12x27 cassette, the total teeth exceed the rear derailleurs published capacity. I always size big-big for safety and avoid small-small but it will do no harm if I inadvertently use it.
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Old 12-26-20, 10:54 AM
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Why not do the method recommended by whomever is the manufacturer of your groupset? If it's a mixed set, then do what is recommended by the manufacturer of your rear derailleur.

Big big plus 1 or 2 links without going through the DR is common, but even Shimano has different recommendations that frequently depend on whether your front is a single, double or triple.
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Old 12-26-20, 11:43 AM
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Why not do both?

I think a lot of people start with big-big with a few extra links and then see how the small-small slack looks. If you have a lot more wrap capacity than you are using, it is easier to avoid extremes.

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Old 12-27-20, 12:41 PM
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Originally Posted by HillRider View Post

I usually modify standard Shimano road triples from 50/39/30 to 50/39/26 and, with a 12x27 cassette, the total teeth exceed the rear derailleurs published capacity. I always size big-big for safety and avoid small-small but it will do no harm if I inadvertently use it.
Where did you source the 26t ring that works with the triple, assuming a 74bcd? thanks
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Old 12-27-20, 01:25 PM
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Originally Posted by calstar View Post
Where did you source the 26t ring that works with the triple? thanks
First, my triple cranks (FC 5703 and FC-6503 and Campy 10-speed Chorus) ) all have a 74mm BCD 5-bolt granny position so any matching BCD chainring will work. I've used SR, Suguino, Vuelta and Shimano labeled rings in both steel and aluminum alloy and from 8,9 and 10-speed groups. Remember, granny chainrings don't have shaped teeth, pins or ramps to aid shifting so they don't have to be part of a "matched set".

Assuming your crank has a similar granny ring configuration, suitable 26T (or 24T too) chainrings should be available NOS at any older bike shop. A Google search for "26T 74mm BCD chainrings" turned up numerous on-line sources.
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Old 12-29-20, 12:02 AM
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Originally Posted by HillRider View Post
First, my triple cranks (FC 5703 and FC-6503 and Campy 10-speed Chorus) ) all have a 74mm BCD 5-bolt granny position so any matching BCD chainring will work. I've used SR, Sugino, Vuelta and Shimano labeled rings in both steel and aluminum alloy and from 8,9 and 10-speed groups. Remember, granny chainrings don't have shaped teeth, pins or ramps to aid shifting so they don't have to be part of a "matched set".

Assuming your crank has a similar granny ring configuration, suitable 26T (or 24T too) chainrings should be available NOS at any older bike shop. A Google search for "26T 74mm BCD chainrings" turned up numerous on-line sources.
I've done this with several Ultegra (FC-6503) cranks. It works fine aside from creating a huge jump from the 24 to the 39 or 42 middle ring. FWIW: a 24 or 26 tooth small ring won't be used often but when you need it, you need it. I used mine for a 4-mile, 12% to 15% climb at the beginning of a long, all-uphill day. My legs were still working at the end of the day, probably because I didn't cook them at the beginning.
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