Bicycle Mechanics - Just add another chainring?
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08-06-10, 04:21 PM
I was looking at an advertisement for my 1986 Bridgestone 400 the other day and noticed that it showed a third, inner chainring as an optional item to have put on the bike.
If I had an extra triple crankset sitting around (which I do), would putting the triple on my Bridgestone be as simple as bolting it on and then adjusting the hi/low on my front derailleur (Suntour AGX)? Or am I really looking at having to find another front derailleur with enough travel to accomidate a triple chainring?
08-06-10, 04:28 PM
Things to keep in mind:
-Do you have the matching bottom bracket?
-Will the front derailleur work okay with a triple? It's not about having enough throw, it's that triple FDs have a deeper inner plate to help shift from inner to middle. My understanding is that this is not so big of a deal with friction. (Were there even triple-specific FDs in the days of friction?)
-Does the rear derailleur have a long enough cage? You should be able to use the big/big combo, and still be able to use the inner chainring with the smallest cogs without the RD folding into itself (due to not being able to take up the slack created).
08-06-10, 06:31 PM
I had exactly the same bike, purchased new, and did add the third ring soon after i got it.
If you still have the original SR crank you can add a third granny ring (standard 74 mm bcd) and you will only need the bolts and spacers to do so. The OEM bottom bracket is long enough to clear the third ring. If you are going to use a different model crank, you will have to try it to see if everything clears.
The original Sun Tour ARX derailleurs will shift the triple just fine and the front will only need to have the inner limit screw readjusted.
08-11-10, 01:38 AM
awesome. thanks for the info hillrider!
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