# 69er tandem??



## ds2199 (Sep 16, 2008)

Has anyone tried putting a 29er fork and front wheel on a 26" mtb tandem? 

I am trying to figure out if there would be unforseen problems? On such a long wheelbase the steering would not change much would it? (not like it would on a standard bike). Standover would be compromised a little bit.

I've been riding 29er more and am beginning to wonder if the benefits of the big front wheel would help in rolling over obstacles (especially since you can't lift the front end on a tandem like you can on a regular mtb - or at least I can't).

Any and all thoughts & opinions welcome.

More info:
Frame in question is ECDM. Currenly running fork with 140mm travel. I have stand over room to give up. I am currently running a few spacers between my stem and headset, so my handlebars would not be raised very much with the bigger wheel/fork.

PS. Yes, I know that a 29er frame would be the ideal way to go. That is not in the current budget, so I'm just wondering if anyone else has thougth of and/or tried above mentioned idea. I'd be out $$ for a new fork and front wheel...:skep:


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## PMK (Oct 12, 2004)

I have not done it, but would say run the 29 and shorten the fork to retain the specs you prefer.

The statement about rolling over stuff is so true. There are things to ride and others to destroy a wheel. A few months ago, I started designing a leading link fork worthy of the tandem. At the moment it's just another project in the list.

PK


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## bsdc (May 1, 2006)

I think your idea is solid. Check the axle to crown distance and you may end up with very minimal geometry changes. Even if there is a change, it will be relatively small on a tandem.


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## Fleas (Jan 19, 2006)

Borrow a 29er wheel to check the handling.

I have an Instigator with a 26" wheel. It is fine. A 29er wheel was not fine.

You may find it is really flip-floppy with the added trail from a 29er wheel. You would have to steepen the head angle (shorten the fork if the ATC allows) somehow to reduce the flip-floppiness, but it may be tolerable as is.

Then build a really strong wheel.

-F


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## ds2199 (Sep 16, 2008)

Thanks for the replies!

I actually thought I'd get more repsonses...

So what forks are available in 29r that are "tandem worthy"? I'm confident that I can get a stout 29" wheel built, but am not sure what forks will work. I understand Alex is using one of the White Brothers' forks for his 29" tandems. Alex, how are those working out? Any idea of the weight on the Magic?

Is anyone else out there riding a 29" tandem out there? "Tandem Rated" or otherwise, I am curious as to people's experience.

thx


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## TandemNut (Mar 12, 2004)

ds2199 said:


> Thanks for the replies!
> 
> I actually thought I'd get more repsonses...
> 
> ...


The WB has worked fine for 29'er use. The ATC is stiffer, but heavier as well and a PITA on front wheel removal. The WB weighs just over 6 lbs in current dual-spring mode, but they're working up a higher rate longer stroke single spring that should bring the weight down slightly (not increased travel, BTW).
JayP and Tracey rode a Rock Shox Reba 29'er on their GDR race last year, with no reported problems. However, together, they both probably weigh what I do alone.
Not a lot of choices out there, unfortunately...


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## MichiganClydesdale (Mar 24, 2004)

*winning choice*

The Eppans, a fast expert team out of the midwest, won the Ore to Shore race a couple years ago on a 96er tandem. I believe they used a surly 1x1 or instigator fork. They've since had a custom 29er tandem made by quiring.


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## Team Fubar Rider (Sep 3, 2003)

Fleas said:


> Borrow a 29er wheel to check the handling.
> 
> I have an Instigator with a 26" wheel. It is fine. A 29er wheel was not fine.
> 
> ...


A 29'er fork and wheel on a 26" tandem will have less of an impact than on a single bike, since the wheelbase is so long. It will have an impact on the handling of the tandem, no doubt, but it might fall into the tolerable range. I'd try it out first if possible. See if you can borrow some parts first.


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## ktm300 (Aug 7, 2006)

The suspension fork, Manitou Splice (definitely not tandem rated), was noodly and made the handling twitchy when compressed.

So thinking that another 3" in front wouldn't hurt, an opinion shared by the stoker:thumbsup: , I put on a Nashbar rigid fork and 29" wheel. The fork dimension A-C corresponded to the Manitou at the top of the stroke.

Voila! Handling is solid, none of that homebrew 96er floppiness. The fat 29er tire absorbs just enough of the dirt path and gravel junk. And the stoker thinks the tandem is now smoother and more predictable.

Only downside is the dreaded toe overlap, but it's not a big problem. Probably will test it with the 26" tire next, and then look for a 650B.


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## eischman (Apr 5, 2005)

I have wondered the same thing especially considering I see so many tandems build around 100mm fork but where people are running 140-200mm forks. I would think that would have a bigger impact than 26in to 27 inch front wheel


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## winbert (Sep 22, 2005)

*Cannondale 96er*

I have a 2002 Cannondale tandem that I've converted to a 96er*. I believe the frame was designed around a rigid Cannondale Fatty fork (A-C ~395mm), but I bought it w/ a Cannondale MotoFR 26" fork (A-C ~420mm sagged). Bike handled OK in singletrack, but had a little flip-flop. I then mounted a rigid Fatty fork which quickened the steering significantly & eliminated the flip-flop, but lowered the front end too much for my comfort & beat me up even w/ a monster 2.5" Trail Bear tire. I then switched to a Surly Big Dummy rigid fork (A-C = 425mm) with a 29er front wheel. I haven't ripped thru any singletrack w/ this setup yet, but dirt-road rides indicate the flip-flop feel is back (but still at an acceptable level).

I would think that putting a 29er _suspension_ fork and 29er wheel on the front of a 26" tandem would make the front end way too tall & really screw up handling, hence my trying rigid (although admittedly it doesn't seem to make sense to put a rigid fork on the front of a full-susp ECDM :???. FYI, I found that I could just barely squeeze a 29er wheel w/ 2.55 WTB Weirwolf tire into a fork w/ 410mm A-C, but went w/ the 425mm Big Dummy so that as larger-volume 29er tires come to market they would still fit. Other rigid 29er fork options (& A-C lengths):
Surly Instigator = 447mm 
Salsa CroMoto 26" disc-only = 445mm 
Salsa CroMoto 26" disc/canti = 425mm 
Surly 1x1 26" = 413mm 
Surly Big Dummy = 425mm 
Surly Pugsley (135mm spacing) = 447mm 
Vicious Cycles 26" = 438mm 
Zion 26" = 457mm

Salsa hasn't tested their CroMoto's on a tandem so they can't endorse them. Same thing w/ all the Surly forks except for the Instigator, but I feel very confident using the Big Dummy.

Lastly, I tried to mount a 650b rear wheel on the Cannondale hoping to raise the rear end a bit and lessen the steering angle impact of the tall front end. It wouldn't quite fit (tire rubbed the stoker BB area), and turns out the 650b wheel (w/ 2.1" tire) was only negligibly taller overall than my 26" rear wheel w/ a 2.4" Motoraptor tire mounted.

Good luck & let us know what you try!
winbert

p.s. I also now have a Fandango w/ Maverick DUC32 fork & love it! If that ever fits into your budget I highly recommend it ...

*I _so_ appreciate MIClyde & ktm300 using "96er" :thumbsup: instead of 69er. I've always thought that since the 29er wheel is in front having the 9 before the 6 was more logical. Reversing it for a little sexual innuendo doesn't seem worth it...


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## PMK (Oct 12, 2004)

FWIW, the dimensions for axle to crown are important but only a portion of the comparison, and handling also.

The fork rake or offset is very important also.

Both dimensions when combined with the headtube angle determine trail. This can give a better insight for comparing all those forks, espicially if the headtube angles are known.

PK


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