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How can you tell if a frame will take a triple?(5 posts)

How can you tell if a frame will take a triple?GMS
Sep 8, 2002 3:44 PM
I've been told that some frames, such as a TCR frame, physically cannot accept a triple crank due to the proximity of the chainstays to the chainrings. The inner ring of the triple would hit the chainstay.

I imagine there are other frames like this, but I have never seen a frame (including the TCR) that specifies that it cannot accept a triple. How can you tell?

I imagine there is some hack to get a triple to fit on a TCR, such as a big spacer or something, but this isn't ideal, is it?

How do you tell if a frame is a good fit for a triple?

Thank you.
Any frame canKerry
Sep 8, 2002 3:58 PM
It's just a matter of BB axle length. A triple BB axle is longer, moving the CRs away from the frame. If the BB axle is not long enough, you can space them to the right very easily, so any frame can work. The question is how well it will work. Problems with triples are more likely from short chainstays (tougher chain angles).
Any frame canGMS
Sep 8, 2002 5:02 PM
Is there any reason my LBS would tell me that a triple wouldn't physically fit on a TCR? Do they just not know?
Any frame canRusty Coggs
Sep 9, 2002 4:15 AM
TCRs are aparently not sold with triples,but OCRs are.Seems like I have seen reference to a clearance indent in the OCR frame(seattube) to allow clearane for the additional derailer movenent.Why don't you ak the LBS for specifics on why and see what they say.Maybe they can show you the difference if they sell Giants.In general most frames will handle triples,but there could be exceptions.
Any frame still canKerry
Sep 9, 2002 5:34 PM
If there is a limitation in derailleur movement (can't get close to the frame) the small chain ring can still be spaced far enough out to allow the use of a triple. You would just get a worse chain line, eliminating the use of a cog or two on the middle and large chain rings. The small ring on a triple is slightly closer to the frame than on a double, but the absolute worst case is that it would be in the same place as with a double (not likely). The derailleur will have to reach farther to make the triple work, but it still should. It is possible that your bike shop is uninformed, just like so many others.