Crank Replacement?
07-20-12, 08:38 PM
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Crank Replacement?
In an effort to better match cadence, I'm looking to replace the stoker crank with a shorter (165mm) crank. I'm having a hard time finding just the crank arms to replace. I'm assuming they can be replaced without having the replace the entire crankset. Am I off my rocket here?
07-21-12, 06:01 AM
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07-21-12, 06:22 AM
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The cranks are currently 175/170. I have a much higher cadence than the wife, so I'm going to replace her 170mm crank with a 165mm. I run a 170mm crank on my single, so I'm hoping the 175/165 combo will slow me down and speed her up.
07-21-12, 10:48 AM
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Both the drive-side and the synch side appear to be standard triple 110/74 spaced cranks. Can I replace these with any cranks set up for a 110/74 triple chainring, or do they need to be tandem-specific components?
07-21-12, 11:21 AM
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The drive side crank will be fine but you will need reverse threading on the non drive side timing crank, so the answer is yes you will need tandem-specific components. You are using a crossover crankset, correct?
07-21-12, 11:40 AM
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Yes, I'm using a crossover crankset.
07-21-12, 03:54 PM
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In answer to your original question, you can buy just the crank arms and re-use your bottom bracket and chainrings BUT the new cranks must use the same style spindle as the old cranks and the chainring patterns have to be the same. Individual tandem crank arms can be hard to come by and it is often cheaper to buy the whole shebang than just the crank arms. Thus the suggestions by others that you contact DaVinci. They will sell you just the crank arms BUT only if your current cranks have a square tapered spindle.
Brent
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07-21-12, 04:03 PM
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With square taper and ISIS or Octalink you can drill-out, re-tap and install Helicoils in the pedal axle holes of a drive side crank to make it work as a timing ring crank. I'm guessing you have square taper cranks based on the age of your Santana from an earlier post to the forum.
To get a complete cross-over crankset without buying a tandem cross-over crankset you just flip the arms and, once again drill-out, tap and install Helicoils to reverse the pedal threading. Now, if you happen to use Speedplay pedals, you can actually 'cheat' by swapping the pedal bodies on the axles and then use a little Loctite on the axles to keep them from unthreading themselves during use.
Not all bike shops have the right taps and Helicoils to do this type of modification, and they're not exactly inexpensive kits to buy for either the home mechanic or a shop that doesn't expect to install them on a regular enough basis to make it worth their while.
Just a FWIW... for those who like to dabble in frankenbike like projects.
07-21-12, 04:42 PM
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With square taper and ISIS or Octalink you can drill-out, re-tap and install Helicoils in the pedal axle holes of a drive side crank to make it work as a timing ring crank....
To get a complete cross-over crankset without buying a tandem cross-over crankset you just flip the arms...
07-21-12, 08:27 PM
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Mechanically something can be done to make it work, real question, does your stoker have it in them to get revved up?
Higher rpm is not for everyone, nice if it is, but not everyone is into it.
PK
Higher rpm is not for everyone, nice if it is, but not everyone is into it.
PK
07-22-12, 06:37 PM
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Thanks for all the input. I sent emails to Precision Tandems and DaVinci Tandems about new cranks.
FYI they are square-tapered cranks.
FYI they are square-tapered cranks.
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