Bike Review: Thesis OB1 Carbon All-Road Bike – Cyclocross Magazine

Thesis Bike co-founder Randall Jacobs is a bike industry veteran. He had once planned to go into the foreign service but felt disillusioned and changed course with the diversion of mountain bike racing.

In the bike industry, he found his calling, moved to Asia and learned Mandarin. For a decade he learned how the global bike industry worked.

Through this experience Jacobs thought he could deliver a better experience to the rider and local bike professionals. His observations:

  • The bike industry is hurting because of internet-price driven consumer
  • Local bike shops are saddled with inventory, but service is where the LBS excels.
  • People don’t know what bike to get.

Jacobs and his co-founder Alice Liu self-funded Thesis Bike and created one bike, the OB1, designed to be ridden anywhere.

The company’s website outlines the Thesis: “Keep it Simple” tops the list. So One Bike, with a nod to old Ben Kenobi: OB1, “Now that’s a name I have not heard for a long time.”

Thesis sent us a blue review OB1, and we put it to good use on all kinds of roads and trails.

Our demo bike was set up with 650b road-plus tires and a dropper post. Thesis OB1 Do-It-All Carbon Bike. © C. Lee / Cyclocross Magazine

Does Thesis pass the test of providing an all-road bike at home everywhere? Find out in our review.

The Frame

The OB1 has a Toray carbon fiber frame with an open mold design. Jacobs sourced the frame from a reputable Taiwanese manufacturer he knows.

Thesis produces the OB1 in small batches and sources materials from Asia with components curated from companies that follow the ethos of the Thesis founders.

Jacobs and Liu seek to offer a bike at a reasonable price with complete transparency about where the cost goes while helping support local bicycle professionals.

As a fluent Mandarin speaker, Jacobs is able to work with Asian companies to customize aspects of the frame.

The rear control lines are internally routed through the carbon frame. Thesis OB1 Do-It-All Carbon Bike. © C. Lee / Cyclocross Magazine

The geometry of the OB1 is fairly standard for a road bike with a 72-degree head tube angle, paired with a 73-degree seat tube, 42cm chainstays and a 7.3cm bottom bracket drop. Those measures combine to yield a 102.5cm wheelbase with a 616mm front center.

Our size L frame has a 57.0cm effective top tube and a tall 180mm headtube giving a reach of 388mm and a stack of 595mm.

The fork axle-to-crown height is also a road-bike-like 385mm, as compared to a cyclocross standard of 395mm.

Longer fork blades accommodate ’cross tire clearance with 700c wheels and mud clearance. This did not present a problem when I put a 700c wheel with a 40mm tire into the OB1 fork.

There is no cable access below the bottom bracket; the control lines run through the frame above the bottom bracket and are foam padded to keep them from rattling. There is a drain hole on the BB shell. The area behind the BB shell is smooth with no mud shelf.

A provision for a direct mount front derailleur is on the seat tube, either electronic shift or bottom pull cable.

The bike comes with a mount for a front derailleur, but our bike was set up 1x. Thesis OB1 Do-It-All Carbon Bike. © C. Lee / Cyclocross Magazine

There are attachment points for fenders, a bento box, a rear rack and five water bottle cages, two in the usual spot, one on each fork leg and one beneath the down tube.

Fork blade mounts often have three bolts for a large format cage like the Salsa Anything Cage, but Jacobs did not like the idea that riders would load too much weight outboard on the fork. Low rider pannier racks will also fit on the fork, and the crown has a piercing for a front rack mount.

The carbon fork has bosses for an auxiliary cage and fenders. Thesis OB1 Do-It-All Carbon Bike. © C. Lee / Cyclocross Magazine

A notable detail of the frame is the integrated reversed seatpost clamp. It offers a nice aesthetic while clamping the post in a secure fashion, unlike hidden bolt compression or wedge systems.

The seat collar is integrated and backward, which is a nice design. Thesis OB1 Do-It-All Carbon Bike. © C. Lee / Cyclocross Magazine

The Build

Jacobs is equally proud of the parts mix he’s curated for the OB1. So much that on the website he explains his reason for choosing every part of the build.

One remarkable example his attention to detail is the DT Swiss 350 hubset on the Thesis-branded wheelsets.

If a buyer chooses to purchase two wheelsets with the OB1, Jacobs seeks out two hubsets from the same lot to assure easier exchange of the wheels without a brake caliper adjustment.

There are two basic build packages available for the OB1 presently based around wheel size and tire width. “The Shredder” is the 650b model and “The Roadie” is the 700c version.

Thesis also offers an “Omni Edition” package that offers two wheelsets, both with tubeless tires set up, rotors and separate cassettes for $1,300 more. (That’s four wheels, four tires, four rotors, and two cassettes!)

Our review sample Thesis OB1 had SRAM Force 22 shifters with a Rival 1 long cage rear derailleur that shifts across a wide-range SunRace 11-46 11-speed cassette.

Our OB1 demo bike came with a wide-range SunRace 11-46t rear cassette. Thesis OB1 Do-It-All Carbon Bike. © C. Lee / Cyclocross Magazine

The hollow-forged crankset has a direct mount single wide-narrow chain ring with 44 teeth, leaving a 108-inch top gear with a lower than one-to-one 26-inch low gear.

The left shifter actuates an internally routed dropper post cable, which is an option available for an additional $200. The post and cable add 250 grams.

The drop section of the black aluminum handlebar has a mild flare, the stem is forged aluminum. The slotted saddle has a short nose and wide rear, similar to the Specialized Power saddle.

Our bike’s 42cm handlebar is slightly flared and the left shifter is set up to control the dropper post. Thesis OB1 Do-It-All Carbon Bike. © C. Lee / Cyclocross Magazine

The Thesis OB1 comes with bar tape that matches the color of the frame, in the case of our review sample, a brilliant blue.

The bottom bracket is EVO 386 and Thesis uses a BB with cups that thread together, similar to the Wheels Manufacturing design.

Chain ring clearance is one of the subtle and sometimes hidden customizations that Jacobs has specified through his close relationship with Thesis frame factory. Thesis OB1 Do-It-All Carbon Bike. © C. Lee / Cyclocross Magazine

The Thesis 650B wheelset has asymmetric rims with a 27.5mm internal width, perfect for the 47mm-wide tires. The wheels have 28 spokes with external nipples laced 2x around DT Swiss 350 hubs with Centerlock rotors for a durable build.

Our build came with 650b x 47mm WTB Byway tires that feature a relatively smooth tread.

The claimed weight for the tubeless wheelset is a reasonable 1,400 grams. Both the 700c and 650b wheelsets are available separately.

Our review bike weighed 21.3 pounds without pedals and 12.6 pounds with no wheels. That’s a bit heavy for a carbon bike, thanks in large part to the dropper post. The company said it is working on a lighter frame.

The Ride

​While reviewing the Thesis OB1, I got the chance to ride with Jacobs after a rainy day. With most of the ride off-road, it became evident that despite the large contact patch of the 47mm tire, the slick tread disallowed traction on wet soil or grass, even with the advantage of staying seated using the low 26 inch gear or descending with the dropper down and in the drops, butt hanging over the rear tire.

He’d set the bike up for me initially with the tires at 35 psi, which is a lot for me with such a high volume tire. Jacobs is a former XC mountain bike pro and intuitively knows that knobs are necessary for any serious off-road pursuits.

He will offer some knobby tire options in the near future as a customized request. He later swapped the WTB Byway smoothies for 650b x 47mm WTB Senderos that have a knob pattern similar to the WTB Resolute or CrossBoss.

That changed the experience for the off-road adventures, especially since rain punctuated our review period.

The rear has a bridgeless seatstay. Thesis OB1 Do-It-All Carbon Bike. © C. Lee / Cyclocross Magazine

Though Jacobs likes the single ring option, he also knows some riders like smaller steps between gears and don’t feel the need for a dropper, so he will offer a double ring setup. I don’t mind the single ring set up as it frees up the left shifter to actuate the dropper post.

I dislike the look and shifting over the ultra-wide range cassette. I would prefer a 38t front ring with a 10-40t cassette on an XD driver.

However, Jacobs explained that availability, cost and weight made him decide on essentially the same range over larger cogs and freewheels, with an added benefit of offering slightly better wear properties.

The 42mm chainstays are 0.5 to 1.0cm shorter than most cyclocross bikes today. That has the theoretical advantage of making the bike more responsive, since more weight is over the rear wheel or because there is less flex of the stays.

These subtleties are not really felt on a bike with big soft tires. However, put on the road wheels and tires and you may think differently.

As discussed earlier, the 700c wheels with road tires have the same rolling diameter as the 650b rims with 47mm tires. That means with a wheel swap, the bike standover and geometry should be the same.

To me it made little difference. I rode the bike with 700c wheels and tires between 30 to 40mm wide and there were no dramatic handling differences. The standover height was noticeable but not bothersome since I primarily ride cyclocross bikes.

Compared to standard 7.0cm BB drop of many modern cyclocross bikes, the lower BB drop was not even noticeable. If I was coming from a high BB bike like the Sage PDXCX or the Fuji Altamira CX 1.1, then it might be apparent.

On the Thesis OB1, 700c wheels with slightly larger rolling diameter than cyclocross tires felt like a normal modern cyclocross bike due to the low bottom bracket the bike starts with.

The limitation of the shorter chainstays is that with 700c wheels, 40mm is the tire clearance limit, perhaps 42mm with a squeeze.

The widest part of the inner chainstays is for a smaller diameter. The bigger diameter also runs close to the seat tube. That’s not a problem, just a consideration.

The OB1 has clearance for 650b x 47mm tires. Thesis OB1 Do-It-All Carbon Bike. © C. Lee / Cyclocross Magazine

The OB1 is available with a package that includes both a 700c and 650b wheelset, each with appropriate tires, rotors and cassette.

Jacobs specs those bikes with the same DT Swiss 350 hubsets from the same production lots if possible for an easy “hot swapping” of the wheels. That means no brake caliper adjustments when switching between 700c wheels with 30mm smooth road tires and 650b with 47mm gravel tires.

The OB1 is a stiff platform. Take into account that I rode the bike with 47mm tires at 20 to 25 psi, much wider than habitual for me. I also rode the OB1 with various other 700c wheelsets with a variety of tires from 33 to 40mm, most typically at 25 -30 psi.

I am lucky to ride a lot of different bikes with various wheelsets and tires repeatedly over the same terrain. Tire compliance helps a lot, but you can still feel the heart of the bike.

Despite what some say, frame compliance plays a role in the overall ride quality. The stiffness is not objectionable and makes the bike feel racy and offers great road manners on pavement. Its ride quality is on par with the Fezzari Shafer.

With cyclocross wheels, 700c with knobbies, or with a monster cross setup, 650b with 47mm knobbies, the fun really began. The frame stiffness, short chainstays and quick front end made tight courses fun.

Despite my preference for a more compliant frame, this bike feels quick, responsive and racy. It handles fast courses with smoother track very well.

When the knobby WTB Senderos were on the Thesis, I can’t help but think of Jacqui Phelan’s drop bar Cunningham mountain bike. Only the brakes are better now, and the dropper post is better than a Hite-Rite.

The dropper post offers the novelty of moving the saddle out of the way for a steep descent or lowering the center of gravity for corners, all adding to the fun.

With the dropper down you can slide back over the rear wheel more easily and brake from the handlebar drops which increases your feeling of control on steep drops. There is no denying this makes descents addictively fast and fun.

I even found myself lowering the saddle a bit when approaching a corner on the road to better rail it. Sometimes I’d lower the saddle at a stop light to stay in the saddle with my feet on the ground just because I could.

The added weight, 250 additional grams up high from the seatpost is noticeable when you carry the bike and when you throw the bike around chicanes. The dropper post is certainly fun to have, especially handily paired to the left shift lever, and it makes the bike more capable.

The dropper post made the OB1 extra fun. Thesis OB1 Do-It-All Carbon Bike. © C. Lee / Cyclocross Magazine

Many riders don’t have the luxury of multiple wheelsets easily swappable on a disc brake equipped bike. With the OB1 two wheel package, that becomes possible for an affordable premium considering the second wheelset comes with tires, rotors and a cassette.

Then you can have one bike that offers great on-road performance and very capable off-road performance.

Though swapping wheels is only a minor inconvenience for someone who likes to work on their own bike, the luxury of having the wheels pre-matched for rotor spacing is nice. You can make your ride decision on a whim knowing it will be adjusted.

The ability to fit 650b with wide tires and all the mounting points makes the OB1 a versatile bike, ready for bikepacking or a long adventure. The stiff frame will be advantageous with a load aboard. The chainstays are short so panniers are not ideal.

Jacobs prefers a frame bag to keep the heavy items low and centered, a preference of modern bike packers anyway. Long haul tourists will likely look for a longer bike specific for the task.

The Verdict

There’s no such thing as a quiver-killer, perhaps a quiver-reducer though. This is Jacobs’ thought of what that best one bike might be.

The Thesis OB1 is a versatile, fun bike, especially with the dropper post and the design around the 650b wheels with the ability to accommodate 700c.

Other similar bikes exist out there, but where Thesis differs is Jacobs’ thought for the sustainability of the bike industry, partnering with shops and local bike professionals. He also is delivering a great bike at a lower cost to the consumer.

We recommend the two wheelset package and the dropper post option. If you are looking for a bike that will cover a lot of ground, the Thesis OB1 should be on our short list.

For more on the Thesis OB1, see the specs and photo gallery below.

Thesis OB1 Specifications

MSRP: $3,300, $3,500 as tested with dropper post option
Frame: Thesis Carbon fiber, 12mm thru-axle, flat mount disc
Fork: Thesis Carbon Fiber with carbon steerer: 1 ⅛” -1 ½”, 12mm thru-axle, flat mount disc
Weight: 21.3 pounds, no pedals; 12.6lbs without wheels or pedals
Shifters: SRAM Force 22 HRD, 11-speed
Crankset: Thesis hollow forged aluminum, 44t Narrow-Wide profile
Brakes: SRAM Force HRD, SRAM Centerline rotors 160mm front, 160mm rear
Cockpit: Thesis 10cm stem, 42cm flared bar
Seatpost: Thesis Aluminum dropper, internal cable routing , 27.2mm, two-bolt clamp
Saddle: Thesis ergonomic
Wheels: Thesis 650b rim, 27.4mm internal width, Centerlock disc hubs, j-bend bladed spokes, external nipples
Tires: WTB Byway tubeless, 650b x 47mm
Warranty: Five years, frame and fork (original owner)
Country of origin: Taiwan
More Info:

Photo Gallery: Thesis OB1 All-Road Bike