Thesis OB1 85% Build Guide

Short answer: it’s far lower than most people think.

We created the guide below as a starting point for determining ideal tire pressures for your particular body, terrain, and riding style. Off-road, the goal is to run low enough for optimal traction and shock-absorption, but high enough to prevent rim impacts over rough terrain. On road, the goal is to minimize rolling resistance and vibration-induced fatigue.

In both cases, because more of your mass will be distributed over the rear axle, consider running your front tire 5-8% lower for improved traction and comfort.

You’ll may notice that our recommended road pressures are substantially lower than what you may be used to with traditional 23/25/28mm tubed tires. Testing has shown that such wider rim/tire combinations offer superior rolling resistance relative to narrower combos. While running pressures that are slightly lower than our recommendations can improve traction and comfort with little-to-no impact on rolling efficiency, running higher than recommended pressures will reduce efficiency along with traction and comfort.

It is completely normal in the beginning for tubeless tires to slowly leak air while the sealant works its magic. The same thin but robust sidewalls that provide such a smooth and efficient ride also have micro-pores that need to be filled, so it is entirely normal for a bit of sealant to weep through during the sealing process.

The best course of action is to ride. The sealant will foam up as it sloshes around, and riding continuously bathes the sidewalls in sealant in a way that a quick shake and spin during assembly cannot. Just be sure to bring a pump, tube, and 6mm hex wrench (for the thru-axles) just in case, as is good practice for all of your rides.

It's pretty darn easy and takes less than 90 seconds. See our video guide below:

650B x 47mm, which sit almost 50mm wide on our 27.3ID rims. We’ve also run the 48mm Panaracer GravelKing SKs with no issues, though they sit ~51mm and thus have a smidge less than our 4mm of recommended clearance. Because 650Bx47mm tires have the same radius as 700Cx30mm, handling remains constant when swapping wheelsets (except, of course, for differences related to the tires themselves).

700C x 40mm. The 22ID rims are aero-optimized for 28-30mm slicks but offer a wide base of support for running higher volume tires at low pressures without inducing tire squirm. Some 42mm tires will also fit, but we’ve not yet tested them and riders on smaller frames may experience toe overlap issues. Note that clearing larger 700C tires would have required a longer/slacker geometry, thus compromising handling.

Dial in your fit with reach adjust. Get more power and control from your SRAM brakes by adjusting them to fit your hands. The adjustment is located between the shift lever blade and the brake lever blade on the underside of the brake lever. Pull back the shift lever to access the 2.5mm hex adjustment screw. When viewed from the bottom, turn the wrench clockwise to move the lever away from the bar and turn the wrench counter-clockwise to move the lever closer to the bar. Once you have your adjustment made, check to make sure that when the brake lever is pulled firmly, it doesn’t bottom out on the handlebar, limiting your braking power.

Levers feel spongy? You may need a re-bleed. While SRAM hydraulic brakes come pre-bled from the factory, the process of cutting and resizing the hoses to route them internally through your bicycle’s frame and fork can introduce enough air to the system to affect brake performance. This is why we recommend re-bleeding each system after installation in our assembly guide. Still having issues after a re-bleed? You may still have air in the system. If the situation doesn’t improve after a few squeezes of the lever, ask your mechanic if another bleed is needed. If bleeding the system yourself, be sure to follow SRAM’s recommended bleed procedure and pay particular attention to how dissolved gasses are removed from the brake fluid (time 0:59).

For more information, check out SRAM’s Road Hydraulic Brake Tips and Tricks.

Yes, but you’ll need a model that doesn’t interfere with the dropper’s operation. Specifically, you’ll want something small and secure that attaches to the saddle rails and not the seatpost itself, and you’ll want to make sure it doesn’t get in the way when the post is fully dropped. Other options for on-bike storage include mounting a bottle cage to the bottom of the downtube for use with a bottle-shaped storage container, mounting a bento to the top of the top tube, or mounting a handlebar bag the bar’s wide central clamping area.

Not that for larger/heavier bikepacking-style seat bags, we recommend using your standard (non-dropper) seatpost.

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