We’ve reported on some extremely lightweight road bikes over the years, but this 5.1kg (11lb) Factor O2 from US bike shop Fairwheel Bikes is definitely one of the lightest disc-equipped bikes we’ve ever seen.
But it could have been much lighter. With a different crankset, carbon disc rotors and a change of tyres, the weight could have been 4.76kg according to Fairwheel. Erring on the side of caution and durability, the bike shop instead wanted to build a bike that was as light as possible whilst still being robust and race-worthy.
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Fairwheel Bikes is no stranger to building one-off custom road bikes that barely get the scales moving, but this latest project was all about trying to build the lightest disc brake road racer. We think it’s fair to say they certainly achieved that.
“The goal for this isn’t necessarily to have the worlds lightest, but rather something that is very light but still race worthy. Actually, it might be both.”
Obviously, if you’re going to build a lightweight bike you need to start with a light frame. The Factor O2 was chosen in a small 52cm size and it weighed 853.2g on the scales. That’s a good starting point.
The fork with a cut steerer tube added 352.1g, and further weight was saved with a Cane Creek AER headset while Tune Magnesium spacers replaced the stock carbon spacers because they come in at just 8.9g apiece.
SRAM’s eTap HRD wireless groupset was chosen and matched with a THM Clavicula SE 300g crankset with an HSC ceramic bottom bracket, which added just 68.1g. The standard SRAM chainrings were whipped off and replaced with a Carbon-ti 50t big ring and Fibre Lyte 34t inner chainring.
The chain and cassette are far from stock as well. A YBN Titanium chain was chosen for its 215.6g weight while the Recon AL 11-25t cassette with its 150.4g weight saves on the mass – though a SRAM Red 11-25t cassette has a claimed 151g weight so it’s a small saving. But at this level, it’s all about the marginal gains…
The disc brakes came in for some weight saving attention too, though I’m not sure if I’d want to save weight on the brakes personally. Ashima Ai2 rotors weighing just 114.3g and even the rotor bolts, Custom Rainbow Ti, saved weight compared to the stock setup.
You can save a load of weight with the right wheel choice, and here Fairwheel really went to town. Extralight SPD hubs (64.9g front, 145.4g rear) combined with FSE prototype rims (442g/pair) and Pillar Xtra Titanium spokes (150.4 for both wheels) and 17.7g worth of Pillar nipples ensure a very lightweight wheelset. A pair of Vittoria Corsa Speed tyres added 377.2g.
Onto the contact points and a 146.6g Schmolke TLO handlebar combined with an 85.1g THM Tibia stem, Lizard Skins DSP tape, Schmolke 78.3g seatpost and Gelu 46.5g saddle. All very lightweight indeed.
You can view the full list of components and weights here.
What’s the bike like to ride? We’ll never know, partly because it’s an expensive trip to the US to find out but also because at 52cm the bike will never fit anyone on the tech team. It does show how crazy attention to detail, and deep pockets, can really shave away loads of weight.
What do you think? Is it a step too far or should more bike manufacturers be aiming for this sort of weight?
54 thoughts on “Bike Check: Fairwheel Bikes’ 5.1kg Factor O2 disc brake road bike”
I would seriously avoid those
I would seriously avoid those particular rotors. There was a story on bike rumors a few years ago about an American guy and his friends doing a long descent down a mountain road and he had these rotors fitted. Because they don’t dissipate enough heat, his brakes boiled and he had to throw himself off the bike at around 40 mph onto the verge at the side of the road
.
StraelGuy wrote:
That’s bad braking not bad brakes!
Also those rotors are a bit chubby on the scales! My MTB rotors weigh 76g rear160mm and 96g for the front180mm I have them on all my bikes and even on long descents they work perform significantly better than stock Shimano’s, they grab a little more but if you’re braking properly this isn’t a bad thing.
Titanium spokes? I shudder to
Titanium spokes? I shudder to think how much they must cost.
hawkinspeter wrote:
Titanium spokes? I shudder to think how much they must cost.
— hawkinspeter
About 10 years ago they were roughly £2 each.
And broke with alarming regularity!
Rapha Nadal wrote:
About 10 years ago they were roughly £2 each.
And broke with alarming regularity!— hawkinspeter
That’s surprising. I’d have guessed that they’d cost a lot more than that.
Also, I’d have thought that titanium would be an almost ideal material for spokes except for it’s tendency to bond with other metals (stuck nipples).
I bet it rides like a dog !
I bet it rides like a dog !
I assume if I have to ask how
I assume if I have to ask how much that build costs, I can’t afford it?!
I think the croissant I had for breakfast weighed more than half the drivetrain! Very impressive.
Don’t like this bike. I
Don’t like this bike. I think it looks like a dog dinner (although that’s just personal taste…) especially the weird positioning of the bars. Looks like it was to get the hoods level because they fastened them on too high.
Wheels could be far lighter, the rims are quite heavy – even aluminium Mavic OpenPro’s are only 430g and they have a brake track. Plus that many spokes seems over kill for a lightweight road bike. My road bike only has 16F/21R and I’m yet to break one and I’m an 82Kg track rider, so no lightweight. Also, while I appreciate they may want the spacers, they could atleast trim the steerer to get rid of the one on top.
Richard1982 wrote:
Those rims are 440g for the pair not each and the stem has to have a spacer on top before tightening down for warranty
Ah didn’t realise it was for
Ah didn’t realise it was for the pair that’s more reasonable! Some top caps (e.g. zipp) now come with a 1-2mm spacer built in for a neat, low finish – that’s what they need, not a ~10mm spacer then a downward pointing cap, just looks messy.
Those rims are 440g for the pair not each and the stem has to have a spacer on top before tightening down for warranty— Richard1982
Richard1982 wrote:
Your lucky streak would come to a swift end if you had a 16h front disc brake wheel
Ah yes, forgot it was disc
Ah yes, forgot it was disc braked, fair enough. I remain unimpressed though 😛
Your lucky streak would come to a swift end if you had a 16h front disc brake wheel— Richard1982
Richard1982 wrote:
Completely agree- it looks like a severely wounded bull about to start its fateful last stagger towards the matador.
rjfrussell wrote:
The bar position is just about the only thing they got right, despite the spacers. Hoods should be lower than the tops, that’s the point of them
Nick T wrote:
That’s not what The Rules say: http://www.velominati.com/the-rules/#46
hawkinspeter wrote:
Rules are for saddos.
don simon wrote:
But these are THE RULES
hawkinspeter wrote:
I think you’ll find that THE BIGGEST SADDOS follow them.
don simon wrote:
How about if I only follow the ones that I want? Does that make me a medium saddo? Or a saddo-wannabe?
hawkinspeter wrote:
I neither know nor care. What do the rules say?
don simon wrote:
They say “Obey The Rules”, but if I’m disregarding that particular rule (No. 1), then I don’t know which variety of saddo that I am.
Maybe I should just follow some of the rules ironically.
hawkinspeter wrote:
I think you’ll find that this rule applies to the bottom hook of the drops, which should be parallel to the ground. Pointing bars up, with the hoods in comfort mode and the brake levers pointed forwards makes you look like Alan Sugar
hawkinspeter wrote:
As Nick T says, they’re talking about the drop part of the bar, not the ramps.
This is what the Velominati mob mean is correct:
Not this:
matthewn5 wrote:
Yep, first one is definitely right, looks rather nice.
That said, I don’t at all care how other people have their bikes setup (providing they are able to use the brakes that is) – I’m just rather particular about mine (that’s one of the frustrations of having mild OCD).
Canyon48 wrote:
Standard bend bars ‘should’ have the bottom part of the drops parallel to the gound (pic 1 above) not rotated up as in pic 2 but if you value comfort over subjective aesthetics then do what you like.
The picture of the Whyte bike earlier in the thread shows compact bend bars which are generally set up with the tops horizontal and with a horizontal transition into the hoods; the set up shown is pretty close to what is ‘correct’ for these type of bars.
Standard bend bars were all the rage when stems were quill and saddle to bar drop was small. If you run a slammed stem and standard bend bars then my compliments to your flexibility and your chiropractor.
Nick T wrote:
No, it’s not.
Carbon chain rings just seem
Carbon chain rings just seem wrong to me in terms of durability
If you look carefully, you
If you look carefully, you can see that the body of the ring is carbon but there appears to be a metal outer ring that has the teeth machined into it.
Really bored of the obsession
Really bored of the obsession with weight saving. I’d prefer if the bike industry concentrated on reliability instead.
Give me a 8.5 kilo bike with components that last 20,000 miles and I’d be much happier.
A sub 821gram wheelset is
A sub 821gram wheelset is mightly impressive!
If anything the frame is the porky part @ 854grams…
peted76 wrote:
Agreed, surely there’s at least 100g to be saved there if not quite a bit more.
it’s kind of a fun project, but will never be the right kind of bike for me even if I had the spare cash
RobD wrote:
They’ve just started selling Factor which is probably why the choice was made
You can definitely get
You can definitely get lighter frames than that. Trek’s top end Emonda is 665g for the disc brake version – forks add another 350g.
It isn’t – itr’s very stretcy and makes it very difficult to build a wheel to a decent tension. Proper pain in the arse. I’d much rather have a wheelset a few grams heavier built with normal triple butted spokes and brass nipples. Alloy ones being another example of the “more trouble than it’s worth” school.
A bike you could race on? Not
A bike you could race on? Not until they scrap the 6.8kg weight restriction, unless you are not in a UCI governed event. The only thing it’s good for is hill climb events (in which case you don’t need discs, inner ring, front brake, drops etc.).
I don’t understand the obsession with building these things. The only benefit of a lightweight build is if you are racing the rest is just showing off how much excess money you have. Of course it’s always satisfying to drop people on superlights 🙂
Why save all that weight and
Why save all that weight and fit it with a compact crank?
Master Bean wrote:
But the weight of the those extra 8 teeth if you go standard…
That looks really nice. I
That looks really nice. I thought 8kg was light weight. Congratulations.
This is wrong…
This is wrong…
It looks like Fairwheel Bikes do not know what they are doing.
I had these rotors on road bike and they just heated up and faded
24 titanium spokes + disk brakes will feel flimsy and wobbly under heavy breaking.
Good luck on long, steep descents!
I had the Ashima rotors on a
I had the Ashima rotors on a couple of MTBs and they were fine.
Maybe not the same kind of speeds as on an open road descent but unless you seriously drag the brakes I reckon it would be pretty hard to boil brakes even with the lack of material on these rotors.
I’ve still got them but been too lazy to fit them to my current MTB.
Alu Recon cassettes are like
Alu Recon cassettes are like biscuits, you only need give them a hard stare and the teeth snap, ‘race day’ cassette that has a high % of not lasting a hard stage race, durability my arse.
Stronglight and SRAM make lighter 50T rings than the Carbon-ti, I had a check of my records and 84g was the lightest 52T ring I used (Stronglight), 29g for a 33T Stronglight, Fibrelyte combo (50/34) are supposedly 77g a pair however.
I was going to buy some Corima 24mm tubs and build them onto my FRM carbon axled hubs, with DT aerolites they were going to be 880-890g for a 24/20 wheelset that wouldn’t be anywhere near as flaky as that in the build. Certainly wouldn’t want to ride ‘prototype’ rims with ti spokes unless I was under 65kg and just out for a genetle pootle on smooth roads!
These builds are utterly pointless, certainly isn’t practical nor durable in any real way, wall art if you like ugly.
And here’s an example of how
And here’s an example of how to get it wrong. That’s how bike fitters set up their customers bikes now though, because all their customers are Freds
Nick T wrote:
Bullshit. I had a professional bike set up and before the appointment my bars/hoods looked similar to the fugly bike the article is about. After all measurements etc were done my bars looked very similar to your pic. There just ISN’T one set up that suits everyone, this is why the things are adjstable in the first place. Your bike bike needs to fit and be comfortable before worrying about how it looks compared to some mythical rule.
Do it as wrong as this if:
Do it as wrong as this if:
a) you don’t give a shit about rules.
b) it encourages you to get out of your car and on to a bike.
Alright settle down
Alright settle down
Nick T wrote:
All’s fine here, Fred.
Well, now I’m confused.
Well, now I’m confused.
@Nick T – that picture is roughly how I have my bars setup and it feels right for me. What’s the issues with that kind of setup?
@Don Simon – I agree in principle, but that bike doesn’t have a front brake and we all know where that can lead.
hawkinspeter wrote:
Oops!
Freds are a right sensitive
Freds are a right sensitive bunch, it seems
Presumably they will want to
Presumably they will want to be able to sell the bike to someone, or just the frame. Slamming the stem and cutting the tube short is fine on your bike if that fits you, but they’d just be limiting their chances of a sale here
Nick T wrote:
I imagine they never considered any of that. Get on the blower mate.
I was talking to the poster
I was talking to the poster above who was complaining about the spacer above the stem, so you can wind your neck back in and figure out how to follow threads without needing to quote the post directly before
Fair shout. As you were.
Fair shout. As you were.
Hmmm. Must go and check my
Hmmm. Must go and check my handlebar setup now.
Just yesterday, I was watching a video about hand positions and the alignment of your wrists when on the hoods: https://www.youtube.com/watch?v=O9jq4WBrKOY
Once STI/Ergopowers were
Once STI/Ergopowers were introduced, bar shape had to evolve to something more like these Deda Piega bars from the 90s:
BUT the drops were still fitted level. That’s why the ‘ramps’ are ‘ramped’.