# X-post: Sandman Outback tandem fatbike.



## bme107 (Jul 23, 2008)

Check out this guy's new ride.
http://forums.mtbr.com/showthread.php?p=7606577#post7606577

I believe it's going to be interesting to follow.


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## TandemNut (Mar 12, 2004)

Yeah, we've been talking to him about the big-tire tandem project. Very interested in the outcome. Could be another evolution of off-road tandem!


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## PMK (Oct 12, 2004)

I spent a little time riding a friends Surly Fat Tire bike. Interestingly different is how I would describe it.

Yes it rolled over small roots and trail junk pretty well, better than a wide tire 29r. It was not a nimble bike at all, with more steering input required than a well setup tandem except in serious soft terrain, where the tandem would stall and the at tire bike plowed through with some effort, but did ride what we might consider walking.

The other noticeable thing with fat tire bikes is that to be effective they must run squishy tires. While not bad on a single, they do squirm a lot. The tandem will be interesting and I'd speculate will have to run tubes.

I'm curious and would love to test ride this in our typical sandy terrain.

PK


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## TandemNut (Mar 12, 2004)

PMK said:


> I'm curious and would love to test ride this in our typical sandy terrain.
> 
> PK


We're looking to bring one in once he's finalized his frame design. I'm curious to see how it rides on our local stuff. You guys can sand-test it for us. As a matter of fact, you can also water test it in da swamps too.


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## PMK (Oct 12, 2004)

Awesome, kinda lick using the seat cushion for a flotation device if you crash at sea in an airplane...we'll cling to the tires until the rescuers get to us.

I do like the bike and the concept. It could be a fun bike for some of the equestrian and powerline trails we have ridden.

PK


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## TandemNut (Mar 12, 2004)

I had quite a long conversation with the designer at Sandman couple of weeks ago. They don't always run super-low tire pressures like the snow bikes do. More like 20-30 psi, which firms the tire up a good bit. Not sure what the weight penalty is for the tires/rims in that size, but being 26" should make them easier to turn. It';ll be fun to test one, and even more of an attention-getter than even a "regular" tandem.


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## PMK (Oct 12, 2004)

TandemNut said:


> I had quite a long conversation with the designer at Sandman couple of weeks ago. They don't always run super-low tire pressures like the snow bikes do. More like 20-30 psi, which firms the tire up a good bit. Not sure what the weight penalty is for the tires/rims in that size, but being 26" should make them easier to turn. It';ll be fun to test one, and even more of an attention-getter than even a "regular" tandem.


20>30psi should be decent, most guys runs soft like a 4wd

PK


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## bme107 (Jul 23, 2008)

TandemNut said:


> Not sure what the weight penalty is for the tires/rims in that size, but being 26" should make them easier to turn. It';ll be fun to test one, and even more of an attention-getter than even a "regular" tandem.


-Rims weigh 700-1100g. Some guys are drilling single wall rims with 1.25" holes between every nipple, using home-brew rims strips, and getting into the mid 700g territory. For initial tandem testing I'd spec one in the 950-1100g range with double walls. Most rims are 32 or 36h, with a few available to drill your own (40-48h) tandem specific pattern.
-Tires weigh 1100-1300g depending on which of the two tread patterns and which TPI you get.
-Tubes weigh 500g +/- for the OEM Surly fat bike tube. Many run smaller DH tubes or even wide XC tubes in order to shave weight. Rumor is there may be a lighter OEM tube coming out, but that may just be internet legend.
It's not uncommon to find a stock fatbike wheel and tire in service at 8+lbs. Add a dozen more spokes and make them heavier gage.....:eekster:

Remember that 26" is the rim size. With the fat tires on their rolling diameter is essentially the same as a typical XC 29er.

I need to go back and re-read the other thread to find the rear hub spec. About 1/2 the single bikes currently available are 135mm and the others are 170mm. If I had to wager a guess about 75% of those being ridden are on the 135mm hubs due to the popularity of the Surly Pugsley and its offset rear and wheel build. I'm hoping Sandman is using the 170mm and centered spec.

The attention paid to fatbikes is nearly that of a tandem. People know what tandems are, yet stare/smile at the novelty of you riding one because they are so rare. Few know what fatbikes are and stare to try and figure out what the hell you are riding. Everyone wants to stop and chat.


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## TandemNut (Mar 12, 2004)

I believe the Sandman is using 160mm rear spacing.


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