# truvativ Hammerschmidt crank on a tandem?



## goodwinworld (Apr 11, 2007)

I have been pondering putting a hammerschmidt crank on our tandem, would it be possible) , I know I would need to weld on iscg mounts, snd would loose my big ring, but I would gain some clearance - and cool looks!

I was wondering if it was possible to replace the bash ring on it with a timing ring and then rin normal cranks with the timing chain hooked directly to the outer ring I would put on the hammerschmidt.
I have not seen one in person, but looking at the bash ring it looks really close to the arm - any ideas? the shifting any time under pressure would be great!

anyone tried this or thought of it?


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## Hurricane Jeff (Jan 1, 2006)

I dont see a reason why it wouldnt work. The only thing I see being a problem, is the leftside crank arm, you would have to use a different arm for the timing gear/ chain.


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## goodwinworld (Apr 11, 2007)

I was actually hoping to do away with the left side timing chain, but after looming at pictures on the right arm, it looks like I would not be able to add a timing ring instead of the bash ring...


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## PMK (Oct 12, 2004)

Not sure about the Truvatives, but I hope I can build our 29'r all right side drive, with a 2x9.

Still thinking about it, especially how much top gear we need or would actually miss.

PK


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## Team Fubar Rider (Sep 3, 2003)

Unfortunately, that "bash guard" on the Hammerschmidt is part of the whole gear box. Doesn't come off, so the only option is to find a timing left side arm that would fit. I think the HS would leave you severely undergeared for tandeming, but that all depends on the team.


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## winbert (Sep 22, 2005)

PMK said:


> Not sure about the Truvatives, but I hope I can build our 29'r all right side drive, with a 2x9. Still thinking about it, *especially how much top gear we need or would actually miss*.


PK - I see you're in Florida dealing w/ not-exactly-mountainous terrain, like here in SE Michigan. FWIW, last fall we built up our new Fandango w/ 2x9 all-right-side-drive and love it. I bought a variety of chainring sizes to try, but for our faster trails the 38/28 x 11-34 has been great. I was also worried about losing top-end vs. our MT800 triple crankset (26/36/*48!*), but since a 38t chainring on a 29er is the approx. equivalent of a 42t chainring on a 26er, it hasn't been that big of a deal for us. FYI - the bike has only seen local singletrack, so YMMV if riding lots of 2-track/dirt roads...

Good luck!
winbert

p.s. Good luck selling your MT800 - that's a sweet-looking ride! I've been lucky enough to keep mine intact (w/ child stoker kit) & have been playing around w/ the fork setup. I hope to use it to let friends/relatives experience tandeming, especially w/ their younger kids on the back helping pedal! :thumbsup:


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## bme107 (Jul 23, 2008)

Excuse my ignorance, but what is the draw to all right side drive? Does it open up selection of crank sets? Is it for the weight savings of not having a spider on the left side crank? What am I missing?


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## highdelll (Oct 3, 2008)

wouldn't the cadences get messed up?

I think an internal gear rear hub is a better option


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## winbert (Sep 22, 2005)

highdelll said:


> wouldn't the cadences get messed up?


If by cadence you mean captain & stoker cranks staying in sync, no problem (assuming you run the same size timing rings front & rear ;-). On that note, when I first installed my child stoker kit for my 3-year-old I figured I'd lower his gear ratio by mounting a slightly smaller timing ring on his cranks vs. his timing ring on the stoker's cranks... whoops, a couple pedal rotations & the child stoker cranks smacked the stoker cranks. Duh...:bluefrown: 



highdelll said:


> I think an internal gear rear hub is a better option


I completely agree that an internally geared hub would be SWEET, but I think the only one worthy of MTB-tandem duty is the Rohloff... which costs as much as a Fandango frame :eekster:.



bme107 said:


> Excuse my ignorance, but what is the draw to all right side drive? *Does it open up selection of crank sets?* Is it for the weight savings of not having a spider on the left side crank? What am I missing?


Yup, to allow non-tandem cranks to be used. There's a few posts on the subject in this thread.

FYI - agriholic posted this useful link a while back...

winbert


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## highdelll (Oct 3, 2008)

winbert said:


> If by cadence you mean captain & stoker cranks staying in sync, no problem (assuming you run the same size timing rings front & rear ;-).


yeah, whoops - before coffee this morning...I was somehow thinking of an all DS drive setup
I.e. a HS running back to a double ring stoker.
:madman:


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## winbert (Sep 22, 2005)

highdelll said:


> all DS drive setup


Yup, here's an (_updated_) pic:









FYI - the FSA outboard bearing cranks in the previous picture (and still in TandemNut's quote below) didn't work on the Fandango. Under load the 180mm crankarms would just barely flex into the chainstays :eekster: :nono: ... The 180mm XT M751 cranks in the updated pic above work wonderfully. They're not exactly centered on the frame with the 68x118 Octalink V2 bottom bracket, but I've since purchased a 73x113 BB that should center the cranks around the frame, maintain adequate chainstay clearance, and improve the timing chain chainline (currently slightly off but hasn't been an issue)...

winbert


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## TandemNut (Mar 12, 2004)

winbert said:


> Yup, here's a pic:
> 
> 
> 
> ...


Your effective spindle length must be short with that EBB setup. We've got about 12mm of crank clearance on the rear when running a 118mm, or better, a 121mm spindle for the correct chainline.Either that or those cranks are really flexing.


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## PMK (Oct 12, 2004)

I do not believe there is much choice in regards to where the chainline falls, other than minor shimming, when you have a 73mm shell and two piece cranks.

I doubt many two piece mountain cranks are designed around the wider span of the tandems 145 axle and chainstays. 

PK


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## TandemNut (Mar 12, 2004)

PMK said:


> I do not believe there is much choice in regards to where the chainline falls, other than minor shimming, when you have a 73mm shell and two piece cranks.
> 
> I doubt many two piece mountain cranks are designed around the wider span of the tandems 145 axle and chainstays.
> 
> PK


Middleburn's EBB setup will offer different spindle lengths as an option. The same will be true on the Middleburn EBB tandem crankset, whenever we see that.
The Fandango frame not only has 145mm rear spacing, but very short chainstays too, which makes the chainline even further outboard than standard.
So Winbert, have you spent much time on the 2x9 setup yet?


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## winbert (Sep 22, 2005)

TandemNut said:


> So Winbert, have you spent much time on the 2x9 setup yet?


Alex - yes we ran the 2x9 on singletrack all last fall & it worked great (both 36/26 & 38/28). Here in SE Michigan we only used granny on a couple of the toughest climbs, and the 38t was plenty for the fast-flat-straight sections.

I also took the Fandango out on some serious trails in Brown County, Indiana, for a long weekend in early November (anyone familar w/ Brown County knows it flies in the face of Indiana's "flat" reputation). We got the usual "you won't be able to ride a tandem on _this_ trail", but we quickly disproved those notions :cornut:. I had mostly been stoking in MI, but got to captain the whole weekend in IN - I must say the bike handled GREAT and we're extremely happy w/ the purchase - thanks again! :thumbsup:

winbert


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