Coal Bicycles' Prototype Steel 'Park' Bike

 Coal story bro

 It's the only coal rollin' I approve of.

 well played

 Bitchin!

 It can't possibly. Possibly they meant 43 lbs.

 No giant cassette or dropper, smaller rear wheel. I worked with someone with a 32lb giant glory with no carbon on it whatsoever. Still skeptical on 33lbs though...

 Maybe the frame weight?

 yeah, I aint buying that weight with a DC fork and DH casing tires. lmao

 @locaroka: hahahaha. closer to reality than that entire build weighing 34lbs!

 cause carbon is the biggest lie in the bike industry

 Steel isn't that heavy my old darkcycles is about 38lb, sons k9 is slightly heavier but under 40lb and both are heavy built full DH spec.

 @phazedplasma: lie? what about? weight? strength? that it exists? lol

 @phazedplasma: that would be boost & superboost

 The weight is correct. Everyone believes carbon is lighter than all other frame materials, but due to the thickness needed on most carbon frames, so they don’t fold in half, they are in some cases heavier than a steel frameset.

 I can confirm the weight 100% - it's Incredible!

 @dh29er: and due to limitations on space on how many layers they can use and still make everything fit they work out on average about as strong as aluminium. Which is one of the reasons the arch on modern forks stick so far out so they can add more layers to the head tube without it hitting the arch when the fork bottoms out.

 Right. My Norco Torrent steel hardtail with a lyric weighs 33.5lbs.

 @Mtbdialed: really, 6 times and you can’t understand what he’s saying?

 @nateb: possibly more......help me understand. go let all the air out of your fork, compress it and see where the arch is in relation to the headtube.

there isnt a fork on the market that the arch passes the crown race seat. lmfao the godamned arch sticks out so it doesn't hit the CSU/steerer....ffs

 Bike is 55lbs but 33 claimed weight with helium in tires

 stated wieght is for the frame.................. (joke btw)

 @thetruejb: I thought this was total BS as my Starling with a single crown fork is more like 35lbs, then I realised there's no dropper and I'm not even sure there's a cassette on it. So with the smaller rear wheel it just might be accurate. Bet that'd be without pedals though.

 @dh29er: 100% true. Gav’s 84 weighs less than my megatower which is similar spec. The DH fork only adds 550 grams. Over a Fox 38. Remove the dropper @600 grams and you’re back where you started. I used to have a Yeti SB66 which was crazy light for an enduro bike and that only had to be shown a rock garden to snap it. Carbon isn’t strong if built light.

 @Mtbdialed: the arch on most forks has been brought forward so manufacturers have more space to increase the layers of carbon around the head tube without it hitting the arch on your lowers when you bottom out your fork.

blisterreview.com/wp-content/uploads/2020/07/zeb-thumbnail-01-640x423.jpg

 @Mtbdialed: ride rigid and the problem goes away

 @dh29er: Your argument make no sense, sorry. Carbon IS in fact lighter than all other frame materials. Thickness (and weight) of most composite frames is due to the fact that manufacturers keep costs low.

There was a review about the Last Tarvo on Pinkbike in April '22. Their carbon frame, hand-made in Germany, weighs in under 5 pounds. The entire bike tested was sub 30 pounds. Show me a steel enduro frame with a comparable weight, please.

 @Henrygoesfastsometimes : Coal is primarily carbon.

en.wikipedia.org/wiki/Coal

 @Norman22: yes we know spend enough money and go to a respectable carbon manufacturer and you could get an unbelievable bespoke custom frame designed for you and your weight perfectly, weighs nothing and next to indestructible but that’s not what we’re getting in mountain biking, we’re getting cheap overbuilt Chinese carbon that’s designed to accommodate everyone from small children all the way up to 6ft 5 men and not bother the warranty department. There’s actually no point using the grade of carbon they use in mountain biking other than it’s cheap to produce and you can sell it for more. Strength wise it works out about the same as aluminium just less robust and quite stiff and harsh and roughly around the same weight as well.

 @thenotoriousmic: I think Robotbike/Atherton does tailor the lugs to the customers weight and riding style. Typically the areas which are carbon too in other carbon bikes. Fair enough, the lugs aren't carbon for Robotbike/Atherton and the tubes won't be tailored though fair enough, these likely aren't critical and you won't save much if you'd try and tune those for the rider. Yet add a lot of complexity (considering these tubes come from New Zealand).

Olsen then. His current bikes are all metal but a few years ago he had a very typical carbon hardtail design with a high rear triangle and built for Pinion gearboxes and belt drives. I discussed bikes with him when I was looking to get a new frame built and he was willing to add more material for some peace of mind. Maybe not criticially engineered but at least these carbon molds allow for that, to add more material should it be needed. Of course if you're buying a stock component, you're getting a stock component. And a stock component will be dimensioned such that will survive the majority of the demographic that fits it. That's the way customer goods are designed. You know pictures of failed components are happily shared on the internet and can damage the reputation of a brand. Kona knows. But if you need something more specific then one could always go down the custom route. A steel frame manufacturer will be easier to play with geometry, a carbon frame manufacturer will be easier to cut back on the reserves and make a product lighter.

 My old 26’ glory with no carbon and fox 40 weights about 34 pounds

 @Norman22: Carbon is lighter until you factor in damage tolerance. Since carbon is easily damaged you need more material, and hence more weight to make it tougher. I know I'd much rather have one steel frame that's perhaps a tiny bit heavier, than a number of light carbon frames that need to be replaced (or indeed you don't have confidence in)

The answer is never as simple as you first think

I've seen studies completed by colleagues in the aerospace industry that showed for many components (especially more complex ones) aluminium provided a much lighter solution. On one big project, carbon was chosen as a political rather than engineering choice. I kind of see the same thing with bikes and marketing!

 @Norman22: THIS ONE! www.vintagesteelbmx.com/product/1983-kuwahara-km-1-mini

 @nevertoofast: the problem that doesn't exist goes away?

 @Norman22: my Mondraker is 28.9lbs, with DD tires on it.....frame and TTX22 shock, axle, dropout and seat collar is 4.8lbs....

it's not just possible, it's highly doable. it costs money in design and testing, where companies like Norco, RM, SC and even Trek and Spesh(non-sworks) just computer model the frame then add extra material to avoid further testing.

 @thenotoriousmic: I am totally with you. In most cases (bikes), the use of carbon offers no advantage over a well-designed aluminium frame (sorry for the additional "i"). I agree that carbon is used in most cases purely for marketing and pricing purposes.

What I always have trouble with are generalizations. "Carbon is worse than steel" or "steel is better than aluminium". Steel is easy to handle, it's durable and can, if designed well, make a good frame. But so does carbon and aluminium. There are pros and cons for all these three materials.

 @phutphutend: this is the truth nobody in any industry really wants to acknowledge. Most, if not all the theoretical benefits of carbon disappear when you factor in damage tolerance.

It was interesting neko mulally citing the alignment consistency as one of the main benefits he saw of a carbon rear triangle over aluminum.

 @phutphutend: A key consideration is probably whether it is a complex part. If the load path is clear, you can gain something by using an anisotropic material like wood, bamboo or indeed a long fibre composite. If loads are more complex or at least the direction varies between various load cases, you need your fibres oriented in all these directions that something from an isotropic material (like a metal) is actually the lighter solution. I think Robotbike/Atherton really are onto something basically making the complex junctions out of metal and then the longer parts out composite. But even there of course. A frame is a pretty flat (in the vertical plane) piece yet it is subject to a lot of torsion if you tilt the bike in a flat corner or stomp on the pedals and pull the bars. A large diameter downtube helps there (especially if it is wound, like the one from Robotbike/Atherton) yet then it isn't so much optimized for the load case where you hit a square edge bump with the front wheel.

One of the few places where I do think it really has a structural advantage over the steel alternative is the spokes of a conventional wheel. Yet still, steel has become so amazing over the years, it will always be hard to beat.

 @dh29er: right..... that's why you see so many steel parts in aerospace where weight REALLY matters

 A Specialized Stumpjumper Evo Frame, size s4, weighs under 2.8kg WITH a fox DPX and all hardware. The lightest comparable aluminum frame is the Last Glen (Last specializes in lightweight bikes), with a comparable light-piggy back trail shock, is just over 2.9kg. The Stumpjumper Evo isn't even the lightest carbon frame in this category.


Does anyone here seriously think that the Carbon Stumpjumper is less trustworthy, less robust, or less crashproof?

Additionally, aluminum has a set fatigue life. Most, if not all, aluminum mountain bike frames will eventually crack. I've cracked every aluminum frame I've owned except my Ventana El Cuevo DH bike that was built like a tank. Carbon will last for decades if not stored in direct sunlight, assuming no catastrophic crashes.

 @k-n-i-x-o-n: You're correct. There is indeed a lot of steel being used in aerospace. Especially in places where room is confined or where a component is being loaded by pure tensile or compressive loads (like cables for steering). Aluminum is only useful when you want to create volume/distance, like for components subject to bending or torsion.

 @Mtbdialed: coil fork so I can't help you there.

 @nateb: pull the coil out then. lol

 @hamncheez: "Does anyone here seriously think that the Carbon Stumpjumper is less trustworthy, less robust, or less crashproof?"

Yes, I think just about everyone does, relative to an equivalent metal frame.

Would you really feel more at ease crashing in a rock garden with a carbon bike?

 @wburnes: It depends on the carbon bike. A Specialized? yes, yes yes! I've broken many aluminum frames, never a carbon one.

 to right...

 I think we're waiting for pricing info.

 Unfortunately thats all that was in stock

 2019 NP Mega 275 alloy comp, NX build, tubeless worn michelin enduro 2.4, with pedals, 33.8 lb Never weighed it with my DD park tires on.

 website says frames are built to order, company is probably just a few people

 @SATN-XC: it is just the one guy making them

 Holy shit I thought someone was going to have to explain how the world works for a second in the pink bike comments section

 @Compositepro:

 I’m dying

 I'm not sure I follow...2800 or 450 for the frame and shock...is 450 a down payment to get in line?

 @Warburrito: £450 deposit once the frame is complete pay the rest! They are made to order frames

 Yep to me a real park is where the 180-200mm bike isnt overkill.

 26/24 single pivot is the future.

 been single speed for park bike as 5 years, just walk it to lift in morning.

 On Mars where there is less gravity.

 It's the right amount of heavy.

 @tremeer023: 33 pounds for a park bike is really, really good in my book.

Add a dropper and dinner plate cassette, its still 35 pounds with a dual crown fork and proper brakes/tires. I bet if we took a poll of most peoples Enduro bikes it would be right in the middle.

 @hamncheez: Exactly that!

 @hamncheez: yeh it's impressive for sure. This thing looks pretty sweet too. Most of the PB staff bikes weighed more.

 @hamncheez: you believing it is 33lbs is really really bad. lol

 @hamncheez: 2019 NP Mega 275 alloy comp, NX build, tubeless worn michelin enduro 2.4, with pedals, 33.8 lb
Pretty close to that with Magic Mary 2.35 addix, don't remember the exact one.
I have never weighed it with my ass guy dhf DD park tires on.