# Clocking tandem cranks?



## BMJ (Sep 16, 2005)

Is running the captain and stoker cranks in unisen the only proper way to line them up?

Could they be run a quarter rotation different from one another so as to limit the dead spot and rid pulsation from the front suspension?


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## Speedub.Nate (Dec 31, 2003)

I don't have an opinion to offer -- I'm new at this and we run ours "in phase." But search the web for "in phase" and "out of phase" tandem cranks and you'll come up with a lot of reading material.

Most of it pertains to road tandems and discusses 90° alignments, which may not be such a great thing for off-road riding (obstacle clearance an all that), but you'll also find references alignment changes of just a few teeth, as well as some opinions on da Vinci's Independent Coasting System.


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## Trails4Two (May 12, 2008)

BMJ,

If you can just talk Alan an Ted at chumba into making the Evo tandem they designed you wouldn't care about in-phase....

Seriously, most arguments comedown to smoothness vs. obstacle clearance. Also finding a comfortable foot position for both riders on longer downhills. There has also been much discussion of this over on Double Forte.


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## bbudell (Jun 10, 2005)

It greatly depends on what your stoker likes (coasting with a pedal slightly up/down can be weird feeling and out-of-the-saddle climbing is tougher) but we have been running about 20 degrees out of phase and it has made a significant difference in climbing traction. On Double Forte I listed off the benifits (http://sports.groups.yahoo.com/group/DOUBLE_FORTE/message/16060) that we found from this setup and after racing that way for 100 miles I still think it offered an advantage for that course (sandy and loose climbs that you had to stay seated for). On other courses with out-of-the-saddle climbing it might not be as good a setup. We didn't run into any pedal clearace issues with being only 20 degrees out of phase.

The only thing I can add since my DF posting is that we experimented with captain leading vs stoker leading and found that it was easier for the stoker to feel when to soft pedal for shifts when the captain lead.


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## BMJ (Sep 16, 2005)

*Thanks guys!*

I really only use the tandem on gravel carriage roads at this time. Clearance isn't currently an issue. I guess it comes down to experimention. I'll check those links.

Chumba makes a tandem?


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## TandemNut (Mar 12, 2004)

BMJ said:


> Chumba makes a tandem?


They used to. Haven't been able to get them to make one since Ted left. I keep trying though...


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## BMJ (Sep 16, 2005)

*Where's Ted?*



BigNut said:


> They used to. Haven't been able to get them to make one since Ted left. I keep trying though...


Chumba's web site makes it look like he's still with them? Who's designing for them now?


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## Trails4Two (May 12, 2008)

Hey BigNut, did you ever actually get to see one of the Chumba tandems? I just got an XCL from them and it's quite nice. If we weren't already set with the Ventana I would be on the phone bothering Chumba about a tandem frame.
Do you still have the picture that was on you web site?


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## Speedub.Nate (Dec 31, 2003)

bbudell said:


> It greatly depends on what your stoker likes (coasting with a pedal slightly up/down can be weird feeling and out-of-the-saddle climbing is tougher) but we have been running about 20 degrees out of phase and it has made a significant difference in climbing traction. On Double Forte I listed off the benifits (http://sports.groups.yahoo.com/group/DOUBLE_FORTE/message/16060) that we found from this setup and after racing that way for 100 miles I still think it offered an advantage for that course (sandy and loose climbs that you had to stay seated for). On other courses with out-of-the-saddle climbing it might not be as good a setup. We didn't run into any pedal clearace issues with being only 20 degrees out of phase.
> 
> The only thing I can add since my DF posting is that we experimented with captain leading vs stoker leading and found that it was easier for the stoker to feel when to soft pedal for shifts when the captain lead.


I want to try this, but want to first ride more miles in-phase -- now that we're riding regularly again -- so that I know what I'm comparing against.

20° out-of-phase is only 2 teeth on our 38T timing rings. Is that about what you've got? It doesn't seem like much.

I'm contemplating captain leading versus stoker leading. I understand your point about the shifts, and it's as important to me shifting the Speedhub as it would be on a derailleur drivetrain. But I'm wondering if there are any benefits to the *ahem* _less strong_ stoker leading and getting a "boost" through the meat of the pedal stroke from the trailing captain?

Obviously it'd be best for me to experiment and answer my own question. But since you've tried it, just curious if this is something you can comment on?

Also, did you try any standing climbing with this arrangement? Standing climbs feel awkward enough as it is. Does the extra 20° misalignment even factor in, or is it too little to notice?


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## bbudell (Jun 10, 2005)

2-3 teeth is about right. Frankly, we never were super uptight about it +/- a tooth and it didn't seem to have that big an effect if we were 3 teeth or 2 teeth off. 

We did a little standing climbing but not much because the trail was pretty loose and it just wasn't feasible most of the time. At first it felt a little weird at first but we just modified the sway of the bike a bit as we were out of the saddle more and it seemed to be working pretty well after a while.

Smoother shifting was the only big thing that we really noticed with captain leading vs. stoker leading. I read someplace that having the stoker lead helped them to sense when to up their effort because they were better able to feel the increased effort required at the pedals without having it masked by the captain's efforts. We didn't really notice anything like that when we tried stoker leading but other teams might. I think the best thing is to play around and try out slightly different setups to see what works best for your team.


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## TandemNut (Mar 12, 2004)

BMJ said:


> Chumba's web site makes it look like he's still with them? Who's designing for them now?


I guess he's back; I read somewhere that he left to pursue some sort of long-term mission trip or something. I've not been able to get him on the phone, and the other guy that answers the phone seems a bit snotty every time I try to talk to them about building tandems (the opposite of Ted). They have "no interest in building tandems at this time". 
I hope my business gets so good I could say I had no interest in building something someone wanted to buy; I'd still build it, but it'd be nice to not need new business.


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