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Triple to Double Crank Conversion(6 posts)

Triple to Double Crank Conversionselmms
Jul 28, 2003 11:34 AM
I am interested in "down-grading" from a Triple Crank to a Double Crank. I have Shimano 105 components (2001 Mfg date) for the front derailer and cranks. Do I need to purchase new parts for move back to the double or is it an adjustment issue?
Thanks for any help you can provide.
No advantage to it, IMO, but...Silverback
Jul 28, 2003 12:00 PM
Front derailleur should work--in fact, if the main issue is appearance (don't want to look like a triple geek), you can make it look like a double to most people just by taking off the small ring and adjusting the low-limit screw so the chain doesn't fall off the inside. Ideally, though, you'd want a new crank (of course) and a somewhat shorter BB spindle, because you won't need the extra space and you can reduce the Q factor (distance between your feet as you pedal) by a few millimeters. A good shop can give you the sizes.
Entirely up to you, of course, but this is one of those swaps that makes no sense to me. You don't gain anything, and you give up the granny gear the one day a year that you need it. But I'm a lousy climber....
selmms
Jul 29, 2003 6:57 AM
Thanks for the insight!
re: Triple to Double Crank ConversionRusty Coggs
Jul 28, 2003 12:02 PM
To make the complete conversion as per factory you need Crankset,BB,front and rear derailers. If you just want to ditch the triple crankset,then it can be done with just crank/BB.Cheap way is block the shift to the granny with the low limit screw on the front derailer, toss the granny ring,and put on a 39 instead of the 39.
selmms
Jul 29, 2003 6:58 AM
Thanks for the Insight as well.
re: Triple to Double Crank Conversiontobinb
Jul 29, 2003 9:28 AM
There is a downside to removing your inner ring- if your chain drops it will get really jammed in the space of the missing ring. Even if you carefully set your limit screw, eventually your chain will bounce down there and get really hung up. you cant just pedal it back on because it hangs on the bolt protrusions on the inside of the crank- i got dropped in a race once when i had to stop and fish out my chain. then i tried using a 109mm bb but it just never was quite right, something was wrong with the chain line or triple front derailleur, there was always some rub going on.
Now ive got a dedicated double crank, bb and front der., i also put a short cage on the back and everything runs great. If i was to do it over i would just run the triple while saving for a full part swap, instead of just going half a$$. BTW after i swapped my parts i sold all my triple bits on rbr classifieds in less than a week. good luck!