Ev0lutionz

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.

Bill Kapaun

Big:Big is safest.

Ev0lutionz

So I have to add 2 links yeah and bypass the derauileur ?

Bill Kapaun

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.

HTupolev

"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.

dedhed

A slack chain is probably preferable to ripping off a RD I'd like to think.

Trsnrtr

That's my feeling, too. Some will say, just don't crosschain but that doesn't mean it doesn't happen occasionally.

HillRider

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.

Iride01

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.

70sSanO

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.

John

calstar 

Where did you source the 26t ring that works with the triple, assuming a 74bcd? thanks

HillRider

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.

Jeff Wills

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.