Fatbike Boris X9

Last winter, I frequently drove to get out of the drizzle in Seattle, and then past the snow in the Cascades, to the drier area around Vantage and Ancient Lakes. This winter, I hope to ride in the snow instead, saving a lot on gas and time. A new bike wasn’t really in my budget, but the prices at bikesdirect.com are pretty darn good, and so an order was placed for a Boris X9 back in mid-April. The long-anticipated purchase finally arrived a couple days ago. First, the Christmas-like opening of the box:

Bike in box

Bike in box

Here it is out of the box. Looks like only the handlebar, pedals and seatpost need to be attached.


After removing all the protective tape and putting the parts on, the Boris is shining blackly.

2015 Boris X9

2015 Boris X9

One point of curiosity for me was the tire clearance. After reading a bit more about it now on the Salsa website, it’s obvious that the rear hub and chain line is the limiting factor. Since this bike comes with 170 mm rear drop-out spacing, at most a 4″ tire can go in the rear. A Dillinger 5 does not fit, which is 4.2″ wide at the knobs and about 1″ taller. Shifting the chain to the lowest gears confirms that the VeeRubber Mission 26×4.0 is nearly the biggest that will fit in the rear.

Chain line clearance in lowest gear is about 1/4".

Chain line clearance in lowest gear is about 1/4″.

The frame itself has about 1/2″ clearance around the 4″ tires.

Fork clearance with 4" tire installed.

Fork clearance with 4″ tire installed.

Rear stay clearance with 4" tire installed.

Rear stay clearance with 4″ tire installed.

The bike comes with a pretty decent drivetrain and tires.

Drivetrain is SRAM X9, X7, X5 for rear&front derailleur, and crankset

Drivetrain is SRAM X9, X7, X5 for rear&front derailleur, and crankset

VeeRubber Mission 26x4.0  - 120 tpi tubeless ready. I weighted the rear tire at 1432 g.

VeeRubber Mission 26×4.0 – 120 tpi tubeless ready. I weighted the rear tire at 1432 g.

Actual tire casing width of the 4" Mission tire is 3.9", or 99 mm, after 2 months of riding.

Actual tire casing width of the 4″ Mission tire is 3.9″, or 99 mm, after 2 months of riding.

80 mm wide Weinman rims. The rear wheel including 10-speed cassette and 180 mm rotor weighs 2.280 kg.

80 mm wide Weinman rims. The rear wheel with 10-speed cassette and 180 mm rotor weighs 2.280 kg. The tube adds another 390 g, and the rim strip a bit more.

A quick first ride around the neighborhood and .. frown on my face. The steering is weird! After increasing the tire pressure from 6 psi to 11 psi, it rides more like a bike should. But, it’s still tough to hold a straight line on uneven terrain. Also, going around a corner requires counter-steering, it’s a really odd sensation. Reading up a bit more about this on the Salsa website, reveals that this auto-steer sensation is due to the way you shift your weight over the wide rim – which introduces a new torque. Increasing the tire pressure helps to reduce this, but this is what happens when you square off the tire into a rectangle, instead of a circle, with these wide rims.

How does it fit? I am about 5’10” or 5’11” and bikesdirect recommends the 17″ frame up to 6′. The bike’s a bit on the small side, but not by much. A longer seat post is needed and I will tweak the geometry with different stems.

Next, I tried myself at setting up the rear tubeless. I first tried to follow these instructions, but in the end the sidewall was not well supported by the rim and it was too easy to let air out by merely pressing on the sidewall. That was at around 2 to 4 psi. Maybe it would be fine at higher pressure, but that doesn’t seem like a solid solution for winter riding. I may try the ghetto-tubeless next, where you split a tube down the center and lay it over the rim surface. For now though, the 4″ tubes (390 g, each) are filled with 4 oz of Stans and I am hoping that I won’t have to fix flats on the trail.

I took the Boris over to the Roslyn RatPac trails for a couple hours today. Dropped the rear’s air pressure to around 10 psi and rode up everything. The sensation of big tires without suspension was odd. At slow speeds, it’s almost like a 1″ full suspension bike. Even 2″ rocks are barely noticeable. But at high speed, fast bumps make it shutter badly and it feels more like a rigid bike than a full-suspension bike.

The Boris looking over the Teanaway - perhaps some winter riding will be had there.

The Boris looking over the Teanaway – where hopefully some winter riding will be had.

The Teanaway gets snow, so I am thinking that this will be a good place to ride in winter. Even big loops should be possible there by combining dirt roads and trails. I am not sure how much snowmobile use the area gets – I’ll see soon enough.

The verdict: It’s not going to be my new favorite single-track bike. But, I am looking forward to putting this thing on snow. I suspect it will need more serious tires for that. Update: First snow ride with new tires.

Good: Great bike for the money ($800 delivered). Nice drivetrain and saddle (WTB V). Stand-over clearance is huge.

Neutral: Handling is taking some getting-used to, for sure. I am surprised people on even bigger (100 mm) rims don’t complain about the self-steer sensation. The weight of around 35 lbs doesn’t really bother me.

Bad: Avid BB7 brakes are not easy to setup the first time and squeal when wet (but they are very powerful). The wheels were not tensioned correctly. Rims cannot easily be converted to tubeless.

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14 Responses to Fatbike Boris X9

  1. Good review of Boris. I’ll look for the snow reports in a few months.

    • 2wheeltrails says:

      I am looking forward to the snow this year. Will let you know how it goes. Another option you hear around here is to ride it along the beach. But, I am not sure about that – it’s really not a good place for a new drivetrain.

  2. Tim Wall says:

    Thx for the review and pics. Mine ( silver) is coming UPS soon – might try to gotubeless but leaning against it for dependability. I think 8 oz of stans per tube or tire is safer due to the volume, but who knows. If I leave the tubes in, I am looking at slime or something that does not dry out – we’ll see. I am about the same height with a 32’ish inseam, but went for the 19″ since my other XC mtb bike is the same and fits me well. Hopefully not too big. I have a shorter stem ready too. I know you can’t beat the bb7s for mechanical and the WTB seat fits a wide range of riders. I will be riding mine in sand, loose trails, and snow on special occasions. My other XC bike is rigid/flat pedal, so this will probably cushy and heavy in comparison – but this bike won’t be about speed. Keep the reviews coming.

    • 2wheeltrails says:

      Glad you found the review helpful and I hope your bike has arrived by now. I’d be interested to know how the 19″ fits. I will try out a longer stem and longer seatpost. I seem to recall that the instructions on the Stan’s bottle say to use 4 oz for fatbike tires, so I tried that.

  3. Tim Wall says:

    Also, I noticed your rim liner changed color on the rear from the first pics. Tubeless attempt, I am guessing?

    • 2wheeltrails says:

      Yup, after deburring the holes in the rim, I installed the spare (yellow) rim strip that came with the bike and taped it down with transparent window tape, which is supposedly good down to -10 F. No problems with leaking, except at the weld seam of the rim. It’s hard to resist tinkering with tubeless, but tire-fitting reliability with this rim is an issue. Looks like the Stan’s 52 mm rim has a profile that makes sense for a wide tire and supposedly they are coming out with an ~80 mm version, soon.

      • Tim Wall says:

        19 is good, fits perfect.Large is 35.4 lbs without pedals. Fork got bent during shipping, but BD should get back to me on Monday, but the bike is still rideable. I picked up 2 surly removeable core light tubes and put 8 oz of slime in each, just for dependability – AZ is thorn and cactus heaven. Yes, different rims would be the ticket for tubeless, The bead fits on the rim so loosely, I am not even going to attempt it – so you are a brave man that I there.
        Going to hit some wet slopply singletrack this AM and get a real test ride in!

  4. 2wheeltrails says:

    I hope you got the fork replaced.
    I am very happy with my medium frame size now that it has a slightly longer stem and longer seat post.
    I tried the ghetto tubeless conversion and it’s a No-Go. The bead is not even close to seating well. The traction of the Mission tires is pretty poor – often I feel as if I am sliding on a wide wooden plank. This needs to be upgraded for snow riding.

  5. Fischer says:

    Got my Boris at the end of the ski season up at Big Sky. Did a little on the snow and then did a beeline back to Seattle. Rode just a couple of times in the summer on single track. Currently back in Big Sky Nov. 2014, and have been riding in the snow the last couple of days at altitude. Here’s what I can tell you about the bike:

    I put on a Larry on the front and a floater on the rear,, and got much lighter tubes. Not even attempting going tubeless. There’s more than enough floatation for me, but I’m weighing in at under 150.

    It’s a blast to ride.

    The tires act as a shock for small rocks, roots, etc.

    It’s fine on single tracks that don’t contain a talus field. Couple of drops and roots are OK, but continuous rocks really shakes you.

    Goes very well in clumpy wet ground. Just keeps on pushing through. Taken this through places I wouldn’t even walk, and aside from having to dismount to get over fallen trees in wet ground, the granny gear just rolls.

    Travels cross country amazingly well. Goes where I could never go on my FS bike. Sidewall hitting rocks or roots doesn’t throw the front wheel around. Most stable bike I’ve been on. When you do hit a rock or obstruction it absorbs and pushes-it doesn’t jerk the bars.

    Taken it out in the snow for the last couple of days. Limits is about 5 to 6″ of fresh snow. Got bogged down in heavy snow where the Cat Tracks have made the snow into mashed potatoes.

    Bike is amazingly stable going down slopes and snow covered roads. Brakes actually work. Bike is tracking straight in snow.

    Climbs amazingly well up snow covered roads that have up to 5″ of snow.
    Used it last year on the snowmobile trails around the resort. It floats just fine.

    So is it worth it. Yes. I would never have bought one at typical retail. This bike is identical to the KHS Four Season. And when I say identical, Ii mean exact and that bike listed for $1700 to $1800, and I didn’t pay for shipping or freight.

    Will be selling my FS bikel

    • 2wheeltrails says:

      Great review – thanks! Looking forward to snow in the Cascades – it’s ice cold now, but all the moisture has disappeared. I’ve been riding my fattie more than I thought I would – and am able to ride steep technical stuff that I wasn’t able to ride on my 29er hardtail. Even balancing is easier on wider rims 🙂

      What kind of tubes are you using?

      • Fischer says:

        Schwalbe 13AF 26 x 2.75. Their number is 70-559. They now have a 26 x 3.00 which wasn’t available when I bought mine. I drilled out my rim to 21/64 or 8mm to accept a schraeder valve. Easy to do. I didn’t want to screw around with a presta if I added slime. The tubes are less than 200 grams. I’m also using a lezyne HV pump. It takes me about 1 1/2 minutes to go from flat to 5 or 6 lbs. Got the pump from Amazon. It has a hose and a little foot peg which means you can pump it up pretty much with the wheel in any position. It’s also very easy pumping.

  6. Pingback: Fatbike winter tires | 2wheeltrails

  7. madpixl says:

    I’m running snowshoe 4.75 tires on mine so they must have made the rear spacing better. I bought in November 2014.

    • 2wheeltrails says:

      Interesting. Does your frame have more clearance than what is shown in my pictures, especially the chain and chain-stays? Tire design allows for the widest point to be anywhere in height, and from pictures online at http://fat-bike.com/2013/10/product-spotlight-vee-tire-snowshoe-26-x-4-7/ it appears that the Snowshoe XL is not very tall. It actually looks rather small. Perhaps that accounts for the difference in fit? I can tell you that a Dillinger 5 in the back was slightly touching the chain stays after inflating it to 10 psi. It’d be interesting to hear if you have more success with your frame!

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