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Are Tandem cranks specialised in regards to the pedal threading?

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Are Tandem cranks specialised in regards to the pedal threading?

Old 11-16-10, 02:54 PM
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Keyser Soze
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Are Tandem cranks specialised in regards to the pedal threading?

Hello experts
I'm currently excited about building a tandem from frame up and joining this wonderful world of cycling, but have a question about the cranks.
Are the chainsets standard? I mean in a regular bike setup you pedal against the loosening of the pedals as you pedal forward, for example for the pilot the cranks would be reversed so that the drive would be on the left, this would mean you are cycling with the loosening direction of the pedals.
Does this make sense? Many thanks
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Old 11-16-10, 03:03 PM
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Brad Bedell
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Yes, they are specific. Though, with the invention of locktite and occasional checking, it can be done with standard cranks. Some companies offer a rethread service, drill it out, new insert.
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Old 11-16-10, 03:59 PM
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Keep your eye on ebay, there are often tandem cranksets available. Even the more economical Tru vativ sets.
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Old 11-16-10, 04:52 PM
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To get around the problem of pedal thread direction when building up a tandem on the cheap with single bike parts, many people opt to run a single-side drive setup, putting the sync chain on the drivetrain side of the bike. You should then still be able to have two chainrings to use for the standard drivetrain, which may be sufficient, but whether it is will depend on the kind of riding you plan to do.
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Old 11-16-10, 07:39 PM
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Originally Posted by steve53mg View Post
Keep your eye on ebay, there are often tandem cranksets available. Even the more economical Tru vativ sets.
+1
We got a Truvativ Elita crankset from ebay and it was very well priced and seems to work well.
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Old 11-16-10, 11:58 PM
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I used a standard Ultegra crankset on the front and had helicoils installed by the LBS.
It works very well.
The reason I did this is the FSA tandem crankset I had originally had a wide Q factor which I did not like.
The rear is a FSA Gossamer tandem crankset.
The problem with using loctite without reversing the threads is the pedals will be facing backwards unless you are using Speedplay or other symmetrical type pedals.
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Old 11-17-10, 12:08 AM
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i just swapped pedal axles on my pedals (actually i turned the plates around on my speedplays) when i changed the front cranks from the 175mm tandem cranks to an old set of 172.5mm standard road cranks. haven't had a problem in about a year since the swap
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Old 11-17-10, 08:26 AM
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Originally Posted by zzzwillzzz View Post
i just swapped pedal axles on my pedals (actually i turned the plates around on my speedplays) when i changed the front cranks from the 175mm tandem cranks to an old set of 172.5mm standard road cranks. haven't had a problem in about a year since the swap
Interesting, I rode with speedplay zero's and didn't modify the pedals when using a road crank. I suppose there might be a difference, but I didn't feel it when using the pedals.
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Old 11-20-10, 10:37 PM
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Pedal threads are over rated. I have single cranks on my tandem and the threads are stock. I have never had an issue, but then again, they are installed tight. I am no expert but the axles on most pedals can be swapped left to right without much issue. I know they work that way with Campy Record pedals as well as Speedplay. The only real issue is finding an extra right axle so you can use it on the stokers left crank.
I was worried when I first rebuilt my Kuwahara but now after a few years, the pedal issue was found to be the biggest non issue I had.
If you really are worried about nothing, then use locktite for that peace of mind.
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Old 11-22-10, 01:47 AM
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Originally Posted by Brad Bedell View Post
Interesting, I rode with speedplay zero's and didn't modify the pedals when using a road crank. I suppose there might be a difference, but I didn't feel it when using the pedals.
i have the older x-series and it seems to help engagement when you flip them around. i figured that out when a friend was having problems with one of his pedals and noticed the metal 'butterfly' was reversed, i put it back that correct way and the problem went away.
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Old 12-21-10, 11:53 PM
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Originally Posted by Keyser Soze View Post
Hello experts
I'm currently excited about building a tandem from frame up and joining this wonderful world of cycling, but have a question about the cranks.
Are the chainsets standard? I mean in a regular bike setup you pedal against the loosening of the pedals as you pedal forward, for example for the pilot the cranks would be reversed so that the drive would be on the left, this would mean you are cycling with the loosening direction of the pedals.
Does this make sense? Many thanks
Yep, most tandem cranksets are threaded differently than most standard cranksets. You can't just "flip" a couple of fixie cranks to the timing chain side. Well you could, but without some serious loctite you'd be constantly dealing with pedals unthreading.

It is critical on a tandem to have the appropriate length crank. Much much more so than on a single. On a single you can compensate for your "shoehorned" 175/170 crankset by changing your cadence to spin it up or by hammering down. However, on a tandem your cadence is a compromise between the captain and stoker. As a function of this, as a rule, most captains and many stokers would be better off with either a longer/shorter crank on their tandem to compensate for this.

Customcranks.de makes custom tandem cranks in whatever length you would prefer (including offset lengths to account for the different leg lengths most people have). Something to consider. Cheap too...

Anyone over 6 feet that is normally proportioned should probably not be using 175mm cranks on their tandem, not if they like their meniscus.
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Old 12-22-10, 11:09 AM
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Originally Posted by mtnbke View Post
...
Anyone over 6 feet that is normally proportioned should probably not be using 175mm cranks on their tandem, not if they like their meniscus.
6'-1" with 175 cranks on our tandem and all my singles except the fixie. Knees are doing well thus far.
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Old 12-28-10, 12:01 AM
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mtnbke
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Originally Posted by Murf524 View Post
6'-1" with 175 cranks on our tandem and all my singles except the fixie. Knees are doing well thus far.
Have you ever even tried 177.5 or 180 cranks for any length of time? I find it hard to believe that 175mm cranks perfectly match your cadence and proportions. It astounds me how many cyclists will have at least one custom frame in their stable, but assume that 175mm cranks are just a natural fit for them along with everyone else.

I'm only 5/6 inches taller than you and I'm using 205mm cranks on my single and 200mm on the tandem.
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Old 12-28-10, 07:25 AM
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Originally Posted by mtnbke View Post
I'm only 5/6 inches taller than you and I'm using 205mm cranks on my single and 200mm on the tandem.
What's your inseam?
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Old 12-29-10, 02:36 PM
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Originally Posted by TandemGeek View Post
What's your inseam?
Bingo, the TGeek nails it.

Overall height means nothing in specing cranks, inseam is the key dimension.
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Old 12-29-10, 05:23 PM
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Originally Posted by diabloridr View Post
...inseam is the key dimension.
Inseam or a similar measurement taken from the head of the Femur are definitely the starting point and there are some pretty good formulas out there.
- The Inseam method is based on multiplying the length of the inseam when measured from the notch of the crotch to the ground in bare feet by .210 or .216 (more or less a range), e.g., 30" x .216 = 6.696", or when converted to millimeters (x 25.4) = 170.0784 mm. Lennard Zinn makes mention of this on his web site, noting he's the primary source for cranks in lengths of 130mm to 220mm.

- The Femur method is based multiplying the length of the leg when measured from the head of the femur (~5" to 6" below the hip bone) to the ground in bare feet by .185, e.g., 36" x .185 = 6.66" or, when converted to millimeters (x25.4) = 169.164 mm. This is the method that Peter White has advocated in his common-sense based fitting approach for many years.
Again, these are merely starting points for getting crank length in the ball park. Some folks may prefer a shorter crank than the benchmark for higher cadence, whereas others may prefer a longer crank if they are a power rider, and obviously personal preference or having an unusually long or short Femur can dictate a different length crank for comfort or optimum performance.

Perhaps you can now see why I'm curious to know what our friend mtnbke's inseam is, as the formulas would suggest it's around 37" if he's running 205mm cranks.

Last edited by TandemGeek; 03-02-11 at 06:05 AM.
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