Thesis OB1 long-term review: Good performance, lots of custom options

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The Thesis OB1 isn’t flashy, and the upstart brand name carries no prestige. It’s not particularly light, it definitely isn’t aero, and in fact, there’s not a ton about it on paper that will blow anyone’s doors off in general. But it’s a very good bike nonetheless, and wonderfully versatile in terms of what you can do with it and where you can ride. And perhaps most important of all to many buyers, it’s a fantastic value (at least for Thesis’s core United States market).

If spec is important to you, go ahead and try to find something better for the money. I dare you.

Story Highlights

  • What it is: A do-it-all road and gravel bike with good value and lots of custom options
  • Frame features: Carbon fiber frame and fork construction, clearance for 700x40mm or 650x47mm tires, mounts for three water bottles and front and rear fenders, convertible internal cable routing, BB386EVO press-fit bottom bracket
  • Weight: 1,257g (actual frame weight, medium size, with hardware); 487g (fork only, pre-cut); 8.99kg (19.84lb, as tested, medium size, without pedals)
  • Price: US$3,500 (international prices based on currency exchange rates)
  • Highs: Good geometry, great spec, outstanding value
  • Lows: Average frame, value equation is region-dependent

The idea behind Thesis

Direct-to-consumer brands such as Canyon, YT, Rose, and others have been steadily growing in popularity for their ability to deliver similar performance as traditional brands, but at substantially reduced prices by virtue of their dramatically streamlined supply chain. Setting aside the long-term ramifications this trend will have on brick-and-mortar retailers, the math is simple as far as end consumers are concerned: by eliminating one layer of markup, consumers are basically able to buy bikes at wholesale.

Thesis takes that approach further still.

One little-discussed secret of the bike industry is that many well-known brands don’t actually make anything; they may do the design and engineering, but the actual manufacturing is farmed out to any number of well-established contract factories that produce on an OEM basis. Many of those factories also sell their own products on the side, usually at heavily discounted prices since they don’t have a popular brand name to justify any sort of premium.

Thesis co-founder Randall Jacobs readily admits that the OB1 is an open mold frame, albeit with a few custom details that were requested specifically for Thesis.

This is where Thesis co-founder Randall Jacobs comes in (Alice Liu is the other half of Thesis — the one that makes sure bills get paid, documents are signed, etc.).

The Thesis OB1 is a so-called “open mold” carbon fiber frame. In other words, it’s a frame that a factory also has in its catalog that is then offered up to whoever is interested in placing a minimum order (in this case, it’s also known as the Carbonda CFR-505). Jacobs readily admits this fact, and doesn’t make any bold claims as to its novelty, but also stresses that it’s not exactly the same as what someone would buy online themselves.

“We added chainring clearance, we added bosses, we added reinforcement under the bosses, we added fiberglass at interfaces with metal so you don’t get galvanic corrosion, and we added SteerSafe,” he said. “The open-mold frame is available directly, but we do a detailed inspection on every one of the frames that arrive in our facility in Taiwan. We bring all the frames in raw, check all the tolerances on the brake interfaces, dropouts, bottom bracket, and anything else, we do any rework that’s necessary, then send it to a high-end paint facility in Taiwan, bring it back in, and do another round of QC. We have customers who have bought the frames directly [from the manufacturer] coming to us with issues, and that’s one of the things we’re ensuring gets done properly.”

The branding is tastefully minimal.

Those frames are then painted in one of five different colors, then dressed in an unusual assortment of components that Jacobs has sourced directly from the manufacturers wherever possible. At launch, Thesis simply had all of these bits drop-shipped to buyers in plain plastic bags, just as an OEM brand would receive them at their own assembly warehouse. The wheels were pre-built and the hydraulic brake lines were assembled and bled, but you otherwise had to figure out how to put everything together from there.

Thesis has since switched to delivering bikes that are mostly assembled at a factory in Taiwan, and it arrives much as how bikes show up to traditional dealers, although Thesis says its bikes are pre-tuned to the point where there’s supposedly almost zero additional work required aside from installing the handlebar and seatpost, fine-tuning the sizing, and pumping up the tires.

Ride quality on the Thesis OB1’s carbon frame is about average despite what the slender seatstays would suggest: not particularly cushy, but not unusually punishing, either.

Thesis has also partnered with a growing number of local fitters and mechanics to help guide you through the process from start to finish — including offering demo bikes, too.

The original retail price of the Thesis has gone up slightly up as a result, but at US$3,500 as shown here with tubeless carbon clinchers and a dropper seatpost, it’s still a solid deal. Thesis recently added a more upscale build kit with SRAM Force eTap AXS 1x setup for US$5,000, or the 2x version for another US$200. Thesis currently sells the OB1 to 21 countries (including the United States, Australia, the United Kingdom, Germany, and Canada), all with a flat US$99 shipping fee.

Pricing for non-US markets are based on straight currency conversion rates, with the buyer responsible for all taxes and duties (and the value equation unfortunately varying as a result).

“One of our core innovations is our sourcing logistics and fulfillment model,” Jacobs continued. “We don’t have a bunch of pre-assembled bikes sitting in the states tying up cashflow. We work directly with high-end factories and their production engineers — I’m over there speaking Mandarin with the guys — we bring in a limited assortment of high-end components, and then everything is built to order. We don’t even paint the frame until an order comes in. And then we drop-ship out of Taiwan, which eliminates a whole lot of middlemen and price-stacking, which lets us do a fully custom build without having incremental costs.”

An open-mold frame, yes, but a pretty good one, and with a few nice touches

The OB1 frame is about as middle-of-the-road as you can get, and I don’t mean that in a bad way.

The “reinforced” Toray 800/700 blend of carbon fiber is generally considered to be medium-modulus in the industry, the geometry is fairly conservative, and tire clearance is pretty accommodating with quoted allowances for 700c setups up to 40mm-wide, and 650b ones up to 47mm. The internal cable routing setup features swappable aluminum ports that can handle a wide range of drivetrain and accessory configurations, there’s room for 46T single or 50/34T double cranksets, it takes a normal-as-can-be 27.2mm-diameter seatpost, and there are mounting points galore, including five water bottles, a top tube feed bag, and front and rear fenders.

The OB1 doesn’t break any new ground in the handling department, either.

The 72-degree head tube angle and 51mm fork offset on my medium sample yield a semi-quick 60mm of trail when paired with a 700x35mm tire. With a 650x47mm tire, it drops to 58mm, but neither is far off the norm. Likewise for the 73mm of bottom bracket drop, 420mm-long chainstays, and 73° seat tube angle.

One very noteworthy addition that Jacobs made is related to safety. Carbon forks are among the most rigorously tested bits in all of cycling, but they’re still not 100% immune to failure — and if a steerer tube fails catastrophically, the consequences are often severe. To that end, every Thesis OB1 fork is equipped with a SteerSafe aluminum sleeve that is permanently bonded to the inside of the carbon steerer, extending down past the upper headset bearings so as to provide some protection against fatigue-related breakage and crushing from overtightened stem clamp bolts.

The extra chunk of aluminum undoubtedly adds some weight, but considering that the OB1 isn’t trying to break any records in that department, it seems like weight very well spent.

The SteerSafe aluminum steerer tube insert extends down past the upper headset bearing as an added safety measure. And you can certainly cut the steerer as you normally would.

Actual weight for my test sample was 1,257g (including hardware and factory-installed guide tubes), plus 487g for the matching fork with an uncut steerer.

A masterclass in spec with lots of customization options

The spec is where the OB1 really shines.

Rather than offer a complete, or even nearly complete, groupset as would be more typically found, the Thesis OB1’s build kit is decidedly eclectic, using name-brand stuff where it’s most appropriate and cost-effective, but no-name stuff elsewhere.

The Thesis carbon rims have a generous 27.3mm internal width, and are easily set up tubeless. The fact that there’s here at all – at this price point – is very impressive.

For example, the SRAM Rival 1 logo is found on the brake/shift levers, rear derailleur, and hydraulic brake calipers (the chain is a SRAM PC-1110), but the 11-46T cassette is sourced from SunRace, and the hollow-forged aluminum crankset comes direct from Taiwanese factory Samox.

Likewise, DT Swiss 350 hubs are used front and rear, but they’re joined to no-name tubeless carbon fiber clincher rims with Pillar stainless steel spokes.

The saddle? It’s shaped like a Specialized Power, but is totally unbranded and made by Velo (who, coincidentally, also manufactures the saddles for Specialized). The aluminum handlebar and forged aluminum stem have no branding on them at all, but the tops are subtly flattened for comfort, the drops are flared by 10° for more control on tricky terrain, and the stem has a convenient (and secure) four-bolt removable faceplate.

Thesis sources the hollow-forged aluminum crankset from Samox, a Taiwanese brand that does a lot of manufacturing for other companies on an OEM basis.

The magic comes in how all of this is put together, and the options that are offered.

I can’t imagine SRAM is keen on bike brands mixing its rear derailleur with the cassette from another brand, but the SunRace 11-46T cluster offers nearly the same total range as SRAM’s 10-42T option (418% vs. 420%) at a 73g weight savings (465g vs. 538g). Similarly, the Samox crankset Thesis uses is made with hollow-forged aluminum arms and a 30mm-diameter aluminum spindle. At a little over 700g for the 170mm-long arms and 42T narrow-wide chainring, it’s about 80g lighter than the Rival 1 unit, and also theoretically more rigid owing to the oversized spindle and larger-profile, hollow (vs. solid) arms.

When it comes to wheels, the rise of disc brakes has taken a lot of the worry out of generic carbon fiber clinchers since heat-related failures are no longer an issue, and Thesis is smart to go with generous internal widths across the board (22-27.4mm, depending on build kit). Hubs are where you more often run into issues with generics, but the DT Swiss 350 units that Thesis uses have a superb reliability record, and it’s also easy to find replacement parts if and when they’re needed.

Unless you’re chasing grams, there’s little practical reason to go higher than Rival on the SRAM hierarchy.

Even better, Thesis provides a surprising amount of choice during the buying process, including 700c vs. 650b wheels, chainring and cassette size, crankarm length, stem length and handlebar width, and even frame and handlebar tape color — all at no additional charge. A dropper post can be added for a modest US$199, too, and power meters are supposedly coming in the near future.

Want to be able to easily switch between both 700c and 650b wheelset? An extra US$1399 not only gets you a second set of hoops, but also the matching tires, cassette, and rotors, all pre-taped, sealed up, and ready to run.

There’s even quiet wisdom in parts that you can’t even see.

Although the frame is equipped with a press-fit bottom bracket shell, it’s filled with a generic machined aluminum thread-together unit to keep creaking at bay. And better yet, the bearing cartridges are Japanese-made bits from highly reputable brand NSK. The internal routing isn’t guided from end to end, but foam sleeves are included to help prevent rattling inside the down tube. And if you want to run a dropper post with a single-ring drivetrain, Thesis will even gut the left-hand shifter so that you can use it as a remote lever for an ultra-tidy setup.

Sorry, folks, the bottom bracket shell isn’t threaded. But the BB386EVO press-fit format at least places the bearings very far outboard on the 86mm-wide shell.

Detail-oriented buyers will love that Thesis provides the thinking behind every component choice on its web site, right down to the thru-axles, chainring, and rear derailleur hanger. It’s an intimate look into Jacobs’ product manager mindset, and one that many potential buyers will appreciate. After all, usually you get no rationale at all behind why a bike is equipped as it is, aside from the assumption that it was the cheapest way to hit a certain price point.

Where the rubber meets the road

All of this sounds fine on paper, but what’s the Thesis OB1 actually like to ride?

I’ve had the pleasure of riding a veritable fleet of superbikes over the years. There are ones like the Scott Addict Gravel that are so stiff, light, and responsive that they feel almost like they pedal themselves when you apply the slightest bit of power. There are ones like the Trek Checkpoint and Cannondale Topstone that are so smooth that you swear your tires are flat. And then there are ones like the Allied Alfa Allroad that take a less aggressive path toward tackling off-road terrain, but feel so much like a good road bike that you’d be happy riding the same bike for both.

Let’s be honest here: the Thesis OB1 is not one of those bikes.

Bikepacking? Check. Fast cruises on pavement? Check. Casual exploring away from the hustle and bustle of modern society? Check.

But if I were in the market for a do-everything drop-bar bike on a limited budget, and still wanted very good overall performance, this would still be in the running.

As one would expect, the medium-modulus frame delivers average stiffness at the bottom bracket and head tube. It’s neither spongy under power nor vague under hard cornering loads, but it also doesn’t feel lightning-quick when you stomp on the pedals or particularly reactive at the slightest hint of steering input.

Nor does that medium stiffness come with copious amounts of rider comfort. It seems to damp most high-frequency vibration just fine, but I wouldn’t otherwise describe the OB1 as being particularly compliant, despite the pencil-thin seatstays. Ride quality on any bike always relies heavily entirely on the tires, but it feels even slightly more so here, especially with the unyielding dropper seatpost that was fitted here. Compounding the issue is the fact that the fork continues that theme, but yet is still flexible enough side to side that it’s possible to induce slight brake rub without too much effort.

The left-hand SRAM Rival lever is gutted so that it can operate as a remote for the dropper seatpost. Very clean and tidy.

Handling-wise, I found the 650b setup to be a tad quick for my liking. Lots of gravel bike options now offer the flexibility of running 650b or 700c wheel-and-tire setups, but switching to the smaller and wider setup still speeds up the handling, which I’d argue is the opposite of what you’d want (I ended up spending much of my time with the OB1 on a 700c setup). Granted, tackling that issue in the way that Cervelo has with its new Aspero would likely be cost-prohibitive given Thesis’s current business model, but perhaps a second fork specific to each fork diameter would be more feasible here.

There are some more minor nuisances. There isn’t a hatch underneath the bottom bracket to help you run the internally routed cables and hoses, so you need to make sure everything is where it needs to be before installing the bottom bracket. It’s critical to get the front brake hose length just right so that it doesn’t rub the paint off of the head tube. And as much as I appreciate the thought process behind the aesthetic design of the profiled seatpost collar, the shape doesn’t quite match the surrounding carbon fiber so it just comes off as a bit sloppy.

The OB1 chassis may not be especially noteworthy, but it’s good enough that it isn’t at all distracting, either. Rarely did I think about any of that when I was riding it; mostly what I concentrated on was how much fun I was having. The OB1 isn’t showy, it’s not prohibitively expensive (relatively speaking, of course), and it isn’t packed with the latest-and-greatest technology. It just gets the job done, and in a manner that’s almost too quietly competent for its own good.

I’m not usually a fan of flared bars, but this subtle bend gradually won me over.

And remember that this is a bike that costs a modest US$3,300 in stock trim – a little more than half what a Moots Routt RSL frame alone costs. Value is always an important thing to consider for any bike, and in the case of the OB1, it’s such a core attribute that it’s impossible to ignore what you’re getting for the money (although, as mentioned earlier, that value equation will vary depending on relative currency values).

Although the frame isn’t unusually light, the complete build fares much better thanks to the smart spec. My medium “Shredder” build with the more dirt-oriented 650b wheel-and-tire package and dropper post tipped the scales at a a hair under 9kg (19.84lb, without pedals or accessories). The smaller-diameter wheels, relatively fast-rolling tires, and low rim weight help the OB1 feel lighter than that number would suggest, and using a standard seatpost would lop another 200g or so off that total, too. Not bad at all.

A big part of that is the wheelset. Carbon hoops aren’t typically found until you spend far more than what Thesis is asking here for the OB1, and these seem quite good. The properly generous internal width offers great support for the 47mm-wide WTB tires, they set up tubeless very easily and hold tires securely, and if only judging by the handful of times I bottomed them on the square-edge chunks of granite that typify Colorado singletrack, they’re apparently rather tough, too. And the fact that they’re built around actual DT Swiss 350 is a huge boon for long-term durability.

Real DT Swiss 350 hubs grace both ends, complete with the usual enviable reliability record and easy availability of replacement parts.

As I’ve noted previously in my experience on the Otso Warakin, the SRAM Rival 1 transmission is a hugely under-heralded workhorse — hardly lustworthy, but functional and reliable nonetheless. Together with that Sunrace cassette, the whole setup works great, offering plenty of range for exploring backroads and trails, and delivering consistently reliable shifts from the 46T sprocket down to the 11T.

The crankset likewise goes about its business with no headaches despite the lack of conspicuous branding, and creaking was a total non-issue.

The same goes for the unbranded handlebar and stem. The flattened tops are pleasantly comfy on bumpy ground, and even for someone like me that normally prefers non-flared drops, the subtle outward flare on these still seemed just-right when things got rowdy. And as far as I’m concerned, aluminum is way to go here given the expected crashes a bike like this is likely to see. Hell, even the saddle is comfy.

The included handlebar tape isn’t very well padded at all, but it’s grippy and tough.

I could have done without the dropper post, though. In my opinion, it adds too much weight for the modest amount of drop it provides (at least for my frame size and saddle height combo), and the frame design’s modestly sloping top tube inherently limits how aggressive you can go in that department, anyway.

I’d also like to see a more trail-oriented tire option. The WTB Byway is a safe choice for mixed-terrain riding, but the low-profile side knobs just don’t provide enough security through loose corners, and leave too much fun on the table. Not everyone will need or want it, of course, but given the breadth of options Thesis already provides, adding another one — particularly one that has such big implications — seems like a reasonable ask.

Nevertheless, this is mostly nitpicky stuff.

Spec vs. chassis

Still, the question remains: is it more important to have a great frame with so-so parts, or a so-so frame with a fantastic build kit?

For the sake of comparison, a similar amount of money to what Thesis asks for the OB1 will also get you a Canyon Grail CF SL 8.0 SL, which offers a more refined frame and SRAM’s nicer Force 1 groupset, albeit with lesser DT Swiss aluminum clincher wheels than the fancy carbon ones on the Thesis. Weight-wise, Canyon says it tips the scales at 8.4kg, or about 400g lighter than the OB1 on an apples-to-apples basis.

The Canyon offers a smoother ride, more cutting-edge technology, and arguably better handling since it’s purpose-built around a single wheel diameter. But it’s also more limiting in terms of scope if you want to ride off-road, and there are no customization options from the factory: no stem length or bar width swaps, stock gearing, one frame color, one wheel diameter. Anything else you want to do will cost you extra.

And then there are other direct-to-consumer gravel bikes that are built around high-quality aluminum frames, like the Mason Bokeh, which costs about the same as the Thesis with comparable spec and offers similar levels of customization, albeit with an alloy chassis that’s a few hundred grams heavier.

When viewed against that sort of tough competition, the Thesis’s value equation still looks pretty good, but it’s not quite the knockout blow that it might seem to be initially.

More than a passing grade

Take a look inside your closet. Do you prefer mixing things up fashion-wise, or do you mostly wear the same thing everyday? Do your tastes vary from season to season, and do you like to keep up with the latest trends?

Think of the Thesis OB1 as the tailored black t-shirt of the gravel bike world: It fits you well, but is rarely the most eye-catching. It doesn’t cost a ton, and is never the front-page image on the magazine. But there’s a reason why it’s the most-worn item in your wardrobe.

There are always things that look better and command more respect than the nice black t-shirt. But then again, with perhaps a little extra accessorizing, it also almost always suits the occasion. Whether or not it suits your style is another matter entirely.

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