Extreme Hill Climber Fat Tire MTB Project.

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Non-flanged M16 axle nut used for Singleator clearance:

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Comparison of non-flanged and flanged nuts, and the flanged nut on the non-drive side:

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In addition to the required tube and tire, all of this additional, optional flat protection goes into the rear tire. It is three Mr. Tuffy tire liners, three old tubes, a DIY tire liner made from an old Surly Lou, and 26 ounces of tire slime. If and when I get another flat, the old tube will be added in as an additional tire liner. Same goes for the next bald tire. As time goes on, the tire gets more and more heavy, with increasing resistance to puncturing road debris. The front tire gets no tire liners and only 20 ounces of slime.

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If you have the old tubes and don't mind the extra weight, the setup below is easy and free, with as much protection against punctures as you want to provide.

Inflate the new tube to enough pressure so as to center the old tubes on there, one at a time. Inflate the new tube a little more, and those old tubes will not even budge.

Everybody with an ebike should be doing this because the motor will accommodate the extra weight.

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The DIY tire liner and Mr. Tuffy liners are pretty aggravating to install because they flop around in the new tire before you install the new tube. This problem is solved by installing the new tube pictured above (with the old tubes already on there, centered!) and then adjusting the air pressure up or down until you can center (by hand) each one of the "strip type" tire liners. The air pressure should be low enough to allow the strips to be moved by hand, but high enough to hold them in place by tension. I do this with the tire oriented vertically and my head inside the hole, looking down on my work and rotating the tire around.

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This is how the bike shop taught me to keep the slime from making too much of a mess:

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Once the tire is at higher air pressures, the strip type liners will stretch, expanding outward for a balanced tire. I would never air down below 15psi lest the tire liners start moving around. I check tire balance before putting the bike into service.

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All of this flat protection work is getting me about 1075 (street) miles between flat tires, which is about the life of the rear tire. I have lost the option to air down, however.

I run Vee Snowshoe XLs and 2XLs at 19psi, Surly Buds at 15psi and Surly Lous at 28psi, all at or very near the maximum recommended tire pressure. Gotta keep all those tire liners in place!

In my experience, the Bontrager tubes and Vee tires are better at resisting punctures than the Surly Bud & Lou tires and Surly tubes. I won't use Surly tubes anymore.

With the tire slime in there, many flats can be repaired by simply reinflating the tire. I rotate the tire until the puncture is at the bottom of the tire. This way gravity pulls the tire slime to the bottom, against the puncture. As you inflate the tire, the air pressure forces the slime through the hole and hopefully the fibers in the slime will seal the puncture. If it doesn't work the first time, rotate the tire around as much as possible (ideally in the repair stand, using motor power) and then try it again. One could even add more slime as a last act of desperation.

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Here is the Performance Curve/Test Report for this motor. The green is efficiency.

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Here is some motor data:

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After I thought I had set up the brake rotor spacing properly, I saw the rotor pictured below, which is not centered in the brake pads. I was willing to put in a 0.2mm rotor spacer, but resetting the spacing at the caliper (loosen caliper bolts, pull brake lever, tighten bolts) fixed it.

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I tried several different types of torque plate mounting bolts, but I settled on these non-powdercoated Grade 12.9 M5 bolts (M5 - 0.8 X 30) with Class 8 nuts. The brake caliper mounting bracket bolts are the same hardness and thread pitch in M6, except they are 25 and 30mm long. Note the flanged axle nut on one side and the non-flanged axle nut on the other side (both M16) in order to allow clearance for the chain tensioner.

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I installed one headset, fork and stem. It was the first time that I used my new headset installation and crown race seating tools, as well as the Chris King cup press and crown race (base plate) adapters, PN THS003A (for 1 1/8" steerer tubes) http://www.avt.bike/WebStore/merchan...ct_Code=THS003.

I used Park Tool Press Fit Retaining Compound http://www.parktool.com/product/pres...-compound-rc-1

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The fork is a Surly Ice Cream Truck 150mm thru-axle http://surlybikes.com/parts/forks/ic...truck_150_fork, which is 4130 Chromoly steel, the same material as the frame. It was gloss black, but I had it powder coated matte black in order to match the frame.

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This is the drawing for a 150mm dropout bare axle. I am ordering three of these with 173mm dropouts and 260mm total length. The last time I bought some of these, they were only $50 each.