Like this site? Help us to make it better.


Factor O2 VAM



A master of climbing – but a bike that's also incredible fun and extremely capable everywhere else
Light and stiff
A good climber
Comfortable ride
Top-line finishing kit
External seatpost looks a bit bulky
Contact: Recommends

This product has been selected to feature in recommends. That means it's not just scored well, but we think it stands out as special. Go to recommends

At every product is thoroughly tested for as long as it takes to get a proper insight into how well it works. Our reviewers are experienced cyclists that we trust to be objective. While we strive to ensure that opinions expressed are backed up by facts, reviews are by their nature an informed opinion, not a definitive verdict. We don't intentionally try to break anything (except locks) but we do try to look for weak points in any design. The overall score is not just an average of the other scores: it reflects both a product's function and value – with value determined by how a product compares with items of similar spec, quality, and price.

What the scores mean

Good scores are more common than bad, because fortunately good products are more common than bad.

  • Exceptional
  • Excellent
  • Very Good
  • Good
  • Quite good
  • Average
  • Not so good
  • Poor
  • Bad
  • Appalling

The new Factor O2 VAM has been designed to be the ultimate lightweight climbing bike – but Factor's designers haven't achieved that by making sacrifices in other areas. A low weight, a great ride quality and top-level finishing kit combine to deliver an excellent bike that allows you to enjoy the cycling experience wherever it takes you, while its geometry allows you to push it hard on descents.

> Buy now: Factor O2 VAM for £9999 from Vires Velo


'Nothing else this light is as fast, nothing this fast is as light.'

That's quite a bold claim from Factor – and to be honest it's not that one that's easy to quantify. But I will agree that its O2 VAM is a very light and very fast bike, especially when you point it upwards.

2024 Factor O2 VAM - riding 4.jpg

But the thing I love most about it is just how damn planted it feels for such a light bike.

2024 Factor O2 VAM - riding 3.jpg

Some lightweight bikes can be buzzy, twitchy and unsettled by rough, washboard road surfaces, which can make them a bit of a handful to ride fast on, especially when you're descending quickly on the far-from-perfect roads we're all so familiar with.

2024 Factor O2 VAM - riding 5.jpg

The O2 VAM is nothing like that.

It has the poise and surefootedness of a weightier bike, which means you can exploit its lack of weight and impressive stiffness wherever you're riding.

2024 Factor O2 VAM - riding 2.jpg

And I think that is a very important point when it comes to making a decision about whether to buy the O2 or not. After all, very few of us need a specialist road bike, especially here in the UK where we don't have extreme mountain passes – and if you're good enough to need a fleet of bikes to fit every specific riding niche, then your team will probably supply them for you.

2023 Factor O2 VAM.jpg

Even if you're out riding on flatter, faster roads, which is probably the O2 VAM's weakest area, you aren't ever going to feel short-changed unless you're in the middle of your club's 10-mile time trial.

2023 Factor O2 VAM - UCI sticker.jpg

Factor says that its O2 VAM does have some aero touches in its design, and in reality it isn't much less efficient than its OSTRO VAM – which of course Factor claims is the fastest aero bike on the market – and I reckon if you fitted some deep-section wheels you aren't going to be at a disadvantage on the level sections between the hills.

2023 Factor O2 VAM - stem and spacers.jpg

It is designed for climbing, though, so this is obviously where it is most comfortable and competent.

2023 Factor O2 VAM - seat stays.jpg

Our build registered just 6.99kg on our scales – a mere 199g over the UCI minimum weight limit – and that makes it extremely responsive and a bike that's very eager to get a move on. Climbing is an absolute joy, and that's true even for a non-climber like me.

2023 Factor O2 VAM - rear.jpg

To be honest, I've never understood the joy of conquering a climb or spending hours trying to win a battle against gravity – but I was quite happy seeking out my local 'chain-snapper' ascents when I was clipped into the Factor.

And the result feels rather rewarding. The frame is very stiff around the bottom bracket and even giving it full beans through the pedals I couldn't feel any flex, so you can definitely class it as efficient.

2023 Factor O2 VAM - frame detail 2.jpg

Ah, but there's always the plus side of climbing – the descent that follows, which is my favourite bit.

As mentioned earlier, the O2 VAM is a confidence-inspiring descender. Our 54cm frame's short, 985mm wheelbase means it feels nimble through the turns, and you won't be surprised to hear it changes direction very quickly indeed.

2023 Factor O2 VAM - front.jpg

But for a bike that has such quick and direct steering, the handling isn't twitchy. It carves a line nicely through bends and it wasn't upset by the high-speed off-camber chicane that sits at the top of my test descent.

2023 Factor O2 VAM - bars 1.jpg

Everywhere else the O2 VAM is a great bike to ride. It doesn't feel as though it needs to be hammered everywhere as it's comfortable too – well, as comfortable as a super-stiff, peloton-ready race machine is ever likely to be. It's not harsh, is what I'm trying to say, and you can bolster that comfort further by running tyres up to 32mm wide.

Frame & Fork

Factor says on its website that it invented a new manufacturing method to create this carbon fibre frameset, which resulted in it having to build a new factory too. It certainly looks the business in all of the paintjobs that Factor offers it in, and with a claimed frame weight of just 700g it's up there (or should that be 'down there'?) with some of the lightest frames on the market.

2023 Factor O2 VAM - top tube.jpg

The tapered head tube accepts the fork's full-carbon steerer, and to keep things running smoothly a CeramicSpeed SLT headset is included in the build.

2023 Factor O2 VAM - top tube detail.jpg

The frame and fork's 32mm clearance isn't the largest that you'll find on a top-end race bike, but from my point of view I think it's more than you need.

2023 Factor O2 VAM - 3.jpg

The O2 VAM comes with a CeramicSpeed bottom bracket. The frame has been designed to accommodate the T47 bottom bracket, which blends a threaded bearing with an internal press-fit mounting.

2023 Factor O2 VAM - bottom bracket.jpg

This allows the use of a wider bottom bracket shell and larger diameter adjoining tubes, without affecting the overall width between the crank arms.

One thing we don't see very often is an external seatpost, which slides over the top of the seatmast, the extended section of the seat tube. Factor says that this works in conjunction with the section of the slender top tube in front of the seat cluster to keep things comfortable by bowing in a controlled way when you hit a bump.

2023 Factor O2 VAM - seat tube junction.jpg

I can't say I'm a fan of the aesthetics, but the O2 VAM is definitely comfortable.

Aside from this, it's pretty much business as usual elsewhere, with 12mm thru-axles and flat-mount callipers.

2023 Factor O2 VAM - fork detail.jpg

There are seven sizes available, which is a good spread for a carbon frame considering all of the moulds required.

2023 Factor O2 VAM - head tube badge.jpg

When it comes to geometry, Factor oddly doesn't provide top tube or head tube lengths in its geometry table, but it does give stack and reach figures of 552mm and 381mm for our 54cm frame, the middle size, which is around 10mm taller than the previous version.

2023 Factor O2 VAM - head tube.jpg

The head angle is 72.5°, the seat angle 74°. This forward-style seating position helps you to get the power down, though the front end isn't as aggressive as some, which helps the O2 VAM to retain that easy riding style even at speed.

Finishing Kit & Pricing

Vires Velo, the UK distributor of Factor's bikes, offers the O2 VAM in four standard builds, with Dura-Ace Di2 or SRAM Red AXS starting at £11,999 and Ultegra Di2 or this model with the latest SRAM Force groupset both costing £9,999.

2023 Factor O2 VAM - front mech.jpg

If you want to build your own O2 VAM, you can go for the Premium Frameset Package that includes frame, fork, integrated bar/stem, seatpost, CeramicSpeed bottom bracket and headset, computer mount and bar tape for £6,300.

2023 Factor O2 VAM - chainstay.jpg

We recently reviewed the latest SRAM Force AXS groupset, and it's fair to say Jamie was very impressed with it.

2023 Factor O2 VAM - rear mech.jpg

Having used this groupset on quite a few bikes recently I'd have to say I'm also a big fan, and you also have the option of speccing a power meter.

2023 Factor O2 VAM - crank.jpg

Our bike came with a 48/35T chainset, though Vires Velo's online bike builder gives you other options, which is paired to a 10-33T cassette. Personally I find that this combination provides an efficient set of gears, thanks to chainrings that are smaller than those used by other brands. I find I can stay in the larger ring for much longer, and the 10T sprocket means you don't lose out on the top end.

2023 Factor O2 VAM - cassette.jpg

I also like the way the shifters work – you use one lever for going up the cassette, the other for bringing the chain back down. Press both at the same time and the chain shifts between chainrings.

2023 Factor O2 VAM - lever.jpg

The braking performance is very good too.

2023 Factor O2 VAM - rear disc brake.jpg

Factor supplies Black Inc components on its builds, which includes our test bike's integrated carbon handlebar and stem. When you order your bike you can choose from a huge selection of handlebar widths and stem lengths, as well as seatmasts with different heights and setback figures.

2023 Factor O2 VAM - bars 3.jpg

I like our test bike's setup. The handlebar shape works well for me, and it has a nice road feel. There's a small amount of flex for comfort and feedback from the road, while still being stiff enough for hard out-of-the-saddle efforts.

2023 Factor O2 VAM - drop bar.jpg

We've reviewed a few Black Inc wheelsets over the last few years and have found them light and impressive performers.

As standard the O2 VAM builds come with Black Inc 28/33 (28mm deep front rim, 33mm rear), but you have the options to go for deeper section 48/58s or some cool-looking five-spoked carbon wheels.

2023 Factor O2 VAM - 4.jpg

Our bike's 28/33s continued the Factor's lightweight theme, having a claimed weight of just 1,118g per pair.

Their hooked carbon fibre rims mean they're compatible with both clincher and tubeless tyres, and they also continue the ceramic theme, with CeramicSpeed supplying the hub bearings.

They're a lovely set of wheels to ride, providing plenty of lateral stiffness and staying true throughout the review period.

2023 Factor O2 VAM - tyre and rim.jpg

The tyres are Goodyear's Eagle F1 Rs, which Emily described as a great all-round race tyre that grips well in the wet or dry. I found their ride supple, which I don't always find is the case with tubeless tyres, and it's the type of tyre that delivers on the performance front without you having to worry about your ride or race being ruined by a proneness to punctures.

2023 Factor O2 VAM - tyre.jpg

You can also choose from a number of different saddles. The standard model is the Selle Italia SLR Boost, though we have the carbon-railed version that would add £175 to the price.

2023 Factor O2 VAM - saddle.jpg

The SLR is a very comfortable saddle, I love its shape and a 3D-printed version is also an option.

2023 Factor O2 VAM - saddle and seatpost.jpg

Value & Competition

Not including any upgrades this bike comes in at £9,999, which while pretty pricey, isn't that extreme for this level of bike.

For instance, the SRAM Red-equipped Giant Defy Advanced SL that Mat recently reviewed is around 600g heavier, though part of that will be down to a larger frame size, and costs £11,499, which is £500 cheaper than the similarly equipped Factor O2 VAM.

The Colnago V4Rs that I tested came with Dura-Ace Di2 with deep-section wheels from the same groupset and will cost you £12,999. In that build it came in just over 7.2kg, which makes it both a littler heavier and a bit pricier than the Factor.

Specialized's super-light S-Works Aethos climber costs £12,000 for either SRAM Red or Shimano Dura-Ace – though the claimed weight for the 56cm frame is an almost unbelievable 585g.

Or for more options at a wide range of prices, our best road bikes buyer's guide is the place to go.


The O2 VAM isn't just a climbing bike – it's a capable machine pretty much anywhere you want to ride it. And crucially, Factor hasn't forgotten the basics in its quest to deliver low weight and impressive stiffness. The ride quality is excellent and Factor's designers have done a great job creating a frame that feels very planted and is an absolute joy to ride.

> Buy now: Factor O2 VAM for £9999 from Vires Velo


A master of climbing – but a bike that's also incredible fun and extremely capable everywhere else test report

Make and model: Factor O2 VAM

Size tested: 56

About the bike

List the components used to build up the bike.

Shifters: SRAM Force AXS

Chainset: SRAM Force 48/35T

Cassette: SRAM Force 10-33T 12spd

Front Mech: SRAM Force AXS

Rear Mech: SRAM Force AXS

Wheels: Black Inc 28/33

Tyres: Goodyear Eagle F1 R

Handlebar: Black Inc intergated carbon

Saddle: Selle Italia SLR

Tell us what the bike is for and who it's aimed at. What do the manufacturers say about it? How does that compare to your own feelings about the bike?

Factor says: "The new O2 VAM is the definitive aero climbing bike. We didn't invent this category, but we did perfect it: nothing else this light is as fast, nothing this fast is as light. It's also extremely stiff, beautifully smooth and descends with the precision, confidence and speed of a fighter pilot. It's the ultimate choice for riders seeking full-course performance on big days in the mountains, whether you're riding the Étape du Tour or racing the Tour de France. It's everything you dreamed of and didn't think possible, a unicorn among bikes."

It's light and stiff, which makes it a great climber, but it's also a competent all-rounder.

Where does this model sit in the range? Tell us briefly about the cheaper options and the more expensive options

The O2 VAM is available as a frameset or in four builds, with this Force the same price as Ultegra, while Red and Dura-Ace are an extra £2,000.

Frame and fork

Overall rating for frame and fork

Tell us about the build quality and finish of the frame and fork?

Stunning quality throughout.

Tell us about the materials used in the frame and fork?

Both the frame and fork are made from high-modulus carbon fibre.

Tell us about the geometry of the frame and fork?

The geometry is race-orientated with a slightly softer edge to the front, which is a little taller than the previous version.

How was the bike in terms of height and reach? How did it compare to other bikes of the same stated size?

The stack and reach figures are fairly typical for this type of bike, no real surprises.

Riding the bike

Was the bike comfortable to ride? Tell us how you felt about the ride quality.

Yes, the Factor was very comfortable to ride thanks to impressive ride quality from the frame.

Did the bike feel stiff in the right places? Did any part of the bike feel too stiff or too flexible?

The frame feels very stiff, especially through the lower parts around the bottom bracket.

How did the bike transfer power? Did it feel efficient?

Its blend of stiffness and low weight combine to deliver excellent power transfer and impressive efficiency.

Was there any toe-clip overlap with the front wheel? If so was it a problem?


How would you describe the steering? Was it lively neutral or unresponsive? Quick.

Tell us some more about the handling. How did the bike feel overall? Did it do particular things well or badly?

This is a fast-handling bike with a direct feel to it, and which offers you plenty of feeling through the handlebar.

Which components had the most effect (good or bad) on the bike's comfort? would you recommend any changes?

I'm a big fan of the Selle Italia SLR both in terms of padding and shape.

Which components had the most effect (good or bad) on the bike's stiffness? would you recommend any changes?

The Black Inc wheels quash any preconceptions that going super-light compromises stiffness.

Which components had the most effect (good or bad) on the bike's efficiency? would you recommend any changes?

Those wheels are very light, which gives the Factor an excellent little surge under acceleration.

Rate the bike for efficiency of power transfer:
Rate the bike for acceleration:
Rate the bike for sprinting:
Rate the bike for high speed stability:
Rate the bike for cruising speed stability:
Rate the bike for low speed stability:
Rate the bike for flat cornering:
Rate the bike for cornering on descents:
Rate the bike for climbing:

The drivetrain

Rate the drivetrain for performance:
Rate the drivetrain for durability:
Rate the drivetrain for weight:

Tell us some more about the drivetrain. Anything you particularly did or didn't like? Any components which didn't work well together?

SRAM's wireless SRAM Force is a stunning groupset that works very well when it comes to shifting and braking.

Wheels and tyres

Rate the wheels for performance:
Rate the wheels for durability:
Rate the wheels for weight:
Rate the wheels for comfort:

Tell us some more about the wheels.Did they work well in the conditions you encountered? Would you change the wheels? If so what for?

Light, stiff and comfortable. Plus they work well for all kinds of riding unless you want the ultimate aero advantage, when you could go for the deeper rims that are an option when you buy the Factor.

Rate the tyres for performance:
Rate the tyres for durability:
Rate the tyres for weight:
Rate the tyres for comfort:

Tell us some more about the tyres. Did they work well in the conditions you encountered? Would you change the tyres? If so what for?

Good all-rounders with decent grip and a good road feel.


Rate the controls for performance:
Rate the controls for durability:
Rate the controls for weight:
Rate the controls for comfort:

Tell us some more about the controls. Any particularly good or bad components? How would the controls work for larger or smaller riders?

The Black Inc handlebar/stem combination is comfortable and has just enough flex for comfort.

Your summary

Did you enjoy riding the bike? Yes

Would you consider buying the bike? Yes

Would you recommend the bike to a friend? Yes

How does the price compare to that of similar bikes in the market, including ones recently tested on

It's around about the same price as many bikes with this level of frame and kit specification, such as the Giant and Colnago bikes that are mentioned in the review.

Rate the bike overall for performance:
Rate the bike overall for value:

Use this box to explain your overall score

A stunning bike throughout with a top-quality frameset and well-specced components. It's a high price, yes, but there isn't a single component that you'd need to upgrade, so it is very much the complete package.

Overall rating: 9/10

About the tester

Age: 44  Height: 180cm  Weight: 76kg

I usually ride: This month's test bike  My best bike is: B'Twin Ultra CF draped in the latest bling test components

I've been riding for: Over 20 years  I ride: Every day  I would class myself as: Expert

I regularly do the following types of riding: time trialling, commuting, club rides, sportives, fixed/singlespeed,

As part of the tech team here at F-At Digital, senior product reviewer Stu spends the majority of his time writing in-depth reviews for, and ebiketips using the knowledge gained from testing over 1,500 pieces of kit (plus 100's of bikes) since starting out as a freelancer back in 2009. After first throwing his leg over a race bike back in 2000, Stu's ridden more than 170,000 miles on road, time-trial, track, and gravel bikes, and while he's put his racing days behind him, he still likes to smash the pedals rather than take things easy. With a background in design and engineering, he has an obsession with how things are developed and manufactured, has a borderline fetish for handbuilt metal frames and finds a rim braked road bike very aesthetically pleasing!

Add new comment


msackman | 2 months ago
1 like

It would be nice to know *a lot* more about that seatpost. Do you cut the mast so to your correct height and then have it run fully inside the external seatpost (a la Giant ISM)? Or does the external seatpost have some way of clamping to the mast at any arbitrary height? If the former, what is the bearing surface, and is there any play in it? If the latter, what is the clamping system and how does it deform the seatpost and/or mast?

Nick T replied to msackman | 2 months ago
1 like

Looks like some sort of wedge system to allow a measure of up/down adjustment, because clamping rings around cylinders isn't sexy enough any more


Prosper0 | 2 months ago

Woah. £10,000 and you only get Force. 

Simon E replied to Prosper0 | 2 months ago
Prosper0 wrote:

Woah. £10,000 and you only get Force. 

Buy a Honda CBR600RR for roughly the same amount of money*.

Or some double-glazed windows. A fancy holiday. Or a secondhand car - and if you choose carefully you'd still have some money left over for a Defy or TCR that will work just as well as the Factor.


* It has the same number of wheels plus a just-over-a-pint-sized engine... but only 6 widely-spaced, clunky gears so a very old-fashioned version of 1x. And it's very heavy; you won't want to carry it up the stairs.

Latest Comments