Most
steel frames we cover on Pinkbike tend to
work with a single pivot suspension design. The simpler kinematics tend to fit with the ethos of small-scale frame builders - simple, reliable and effective. However, Gavin White of Coal Bicycles wanted to do things a bit differently with his 84 frame.
Gavin has been a welder since he was 15 and has worked with a number of small brands around the UK offering OEM services. He says, "If you’ve ridden a steel hardtail from a UK brand, there’s a good chance that I made it." With 26 years of experience, he started thinking about how he would do things differently himself if he were in charge of the full production process and so Coal Bicycles was born. Gavin was inspired by the miners that he grew up surrounded by in England's East Midlands and wanted to build bikes that reflected them - tough and resilient.
He started his range with the
Pony hardtail (that he assures me has more than one trick) and now is trying his hand at a full suspension bike with the 84. Rather than settle for a single pivot, Gavin wanted a virtual pivot design with a floating shock for the pedaling characteristics. For the linkage parts that Gavin couldn't build himself, he teamed up with
Rideworks, another UK company that mainly specializes in machined components, and together the dream came to life.
The bike itself is a 160mm 29er but it can be configured as a mullet thanks to a flip-chip in the lower link. Swapping this over will give the bike an extra 10mm of travel and a more progressive kinematic so Gavin mainly recommends it for bike park riding with the full 29er set up more optimal for everything else.
Details: Coal Bicycles 84Frame Material: Steel, Reynolds 853
Intended Use: Enduro
Travel: 160mm in 29er, 170mm in mullet, 170mm fork
Wheelsize: 29" front and rear or mullet
Head tube angle: 64.5°
Seat Tube Angle: 78° (73° actual)
Sizes: M, L, XL
Availability: First batch of 20 frames released soon
More info: coalbicycles.com At the moment the bike is still in its testing phase but Gavin is hoping to release his first batch of 20 in the next few weeks. He'll then continue to drop small batches as long as there is demand.
All of the graphics are painted including the head badge.
For those dismissing the stress around that area, bear in mind that even V1 Raw Madonnas were failing there (the XLs I think)
edit: just googled it, that's not how it's done. but still, the extra material at the weld should make it limited by the strenght of the tube, if the tube's thick enough it'll live
Even if we had an hypothetical tube with No weld but that shape, it would still be sub optimal.
Again, I need to be careful with me comments here, as this is a prototype. I don't want to bash these guys needlessly over some make do part they already know it's not feasible for production
I agree though; it's not a pleasant solution.
-Walt
you guys were master yodas at birth ain't it? your retard radars ain't working correctly
Also: a few downvotes and a dismissive comment is not getting “shat all over”.
853 is a great material. I first used it in the mid / late 90s (well, whenever it first became available here in OZ), and, despite my concerns as to it being, perhaps, too hard / brittle from it's pronounced air maraging properties, I've never had a failure with regards to weld / HAZE zones. It IS a bastard of a material to ream out seat tubes and face and ream head tubes, , both before and (bloody hell) after welding.........
Perhaps the maker / designer wants the 'dog leg' butt joint to be a feature of their frame?
Each to his own - I dislike such features.
You've the travel of the reservoir during compression, PLUS, the lowering of the Whole shock to deal with. There are a few shocks with far longer / further from the body eye / trunion center line, that they may be trying to account for, too.
Though, on just basic eyeballing and line drawing over a printed picture, I think there is enough clearance for that joint to be further towards the BB area. A friend just said to me perhaps the butt joint is positioned to allow fitment of the 853 sticker - she's a cynical individual.
But, I'd never have such a joint, at such a point (but, I also have No bent tubes on my Suspension frames) . If it HAS to be there, for the previously mentioned Reservoir clearance issues, it would be wise to extend the lower link mount plates to go Across the Butt joint. The designer has the right idea with his welding those existing plates on the neutral axis - just bring them up to cross the butt joint. Lightening holes, with spaced fish mouth cut outs, would keep weight down, while looking 'nice'. That would be far better than say, a 'saddle gusset, with welds on the neutral (outside of the DT) axis only, which is another way to reinforce a butt joint.
Tiny saddle gussets on the headtube to TT and DT, on a 170mm travel bike, that some owners may be going Very hard on, seems a bit inadequate to me (Especially if they are too close to internal tube butting). And the relatively small diameter tubing is of concern - but, you are limited with 853 sizes.
But, I Do tend to build DH frames that are 'somewhat' Hefty....... I just weighed the swingarm that is going on a Pinion DH frame, and it's heavier than many whole Trail frames. Done that heavy, to later, put on my personal E Bike (when / if ever, I make it) . I'll be using lighter gauge and far less materials to make a lighter swingarm for the Pinion frame, when some steel gets to me. Ah, the joys of C19 delays. I'm not talking ounces here, I'm talking pounds / kilos.........
I Love Her!
She's definitely my better half, keeps my Grumpy Old Bastard side in check. Well, just a little........
you don't hear who is talking, you hear who you think is talking. i am giving you crap but it's also positive feedback.
some like to say map is not the territory. think about it, what you think is out there isn't necessarily what IS out there unless you have first hand experience.
I think lots of companies may beg to differ!
First of all, a good few UK brands don't weld their steel hardtail frames in the UK. Cotic, On One, DMR, Pipedream etc have their frames welded in Taiwan or China. I've got a DMR Switchback frame, the sticker says "made in China". Does Gavin live over there to weld these frames?
Then you have brands who actually do make their steel hardtail frames in the UK. Stanton started recently, Curtis and BTR have been doing so since the beginning. I think Stanton welds in house and I'm pretty sure about Curtis and BTR.
Maybe he only meant to say when the welding is actually being outsourced? I was discussing having an Olsen hardtail frame being built (though I eventually went with BTR and a conventional drivetrain) but I didn't want a carbon frame. Olsen only produces in carbon though he offered to have the frame to be built by an external builder he knew. It wouldn't be cheaper (because he was external) but it was steel. Maybe he was indeed considering Gavin.
Looks unfinished now days.
To some of us this is how bikes are suppose to look!
@Serpentras: As a CNC programmer I’m sure you understand your job is to make a part to spec, including price and aesthetic?
Personally, I love the machined look, I also pay the monthly finance on a few machines so from that perspective would rather not watch my spindles running flat out surfacing for no benefit what so ever.
It seems like it’s a funny ‘in joke’ for machinists to hate on machining marks, not that it’s done hope any harm….
But because I was in the medical biz for most of the machining time I could not done it that way. Everything needed to be smooth as silk. Same for the food industry because they all want surfaces to be less sticky.
My CNC parts on my bike are almost free of marks. You need to look really close on the stem and only notice it when you are in the biz. The brakes, well you will notice but not that bad.
As I say, when you are paying the bill for the machine and costing the part, you wont want to spend a long time with your spindle maxed out running surfacing for absolutely no reason, especially when many people like the 'machined look' - its a sign the part has been CNC machined and not a cheap casting etc.
I think you are also confusing 'marks' with deliberate too-path patterning when surfacing - I would class a mark as the finish left on the floor by a flat end-mill or face-mill etc - I wouldnt class this as a mark, its a deliberate aesthetic choice.
It certainly hasnt done companies like Hope, Absolute Black and many others any harm anyway and it does bug me when machinists continually pop up saying 'In my job that Hope brake is classed as unfinished'.
It would be different it if we were looking at random swirls from a fly cut, but in this case they specifically selected a small ball mill and patterned it to create a consistent and interesting pattern that matches the shape of the part. Some people won’t like the look and that’s fine, just like some prefer green to red. But saying it looks unfinished is disingenuous.
I am not confused, by those marks. Thats just a ball instead of a end mill cutter. Very easy to replicate...
You are confused by what I wrote. Look Trickstuff up and then We Are One to get it. The stem almost got no marks. The Direttissima I have got some marks you can spot right away who are NOT intentionally made but can happen. I am way more onto that sleeker stuff like I said. Or just look at intended. Ofc you have the same benefits for this as stuff won't stick easy as those higer Rz surfaces.
This looks like it could be made by an older 3 axis CNC and is almost sleek anyway. Nothing special, there are other MTB projects where you instantly see that it's not possible this way.
A larger diameter then the ball for the end cutter to make the final cut to smooth it out takes way less time then the tiny ball going for a endless journey to create such a pattern. Even if this is an HSC. Both will fly anyway.
This is AL , we cut this right away to the finish. You dont even need a another tool to get it smooth.
This makes me a Snob? I dunno , so be it.
This kind of surface always will remind me of the old school end cutters with many teeth for the rough milling instead of the new ones with only one sharp edge per teeth. That is probably why in my mind it looks unfinished.
And yes saying something ‘looks not done’ makes you a cnc snob, but that’s OK, we don’t all like the same thing.
I think finishing marks with a small endmill isn't ideal either. I prefer a larger finishing tool appearance, and notice most shops will do it.
It was done to give an aesthetic appearance - a deliberate choice - Rideworks is a machine shop, I’m sure they know how to pick between types of tooling and if you haven’t seen anyone in 20+ years 3D surface a part and you are genuinely in the CNC industry.
Man you ‘CNC gurus’ are an odd bunch.
I haven't seen Hope or Absolute Black parts before. I had a look at the latter, and don't like them. But that's only an opinion.
It's funny because before I was getting into the job I had already parts and items who are made with only a sleek finish. I had even an MP3 player back then who was CNC made and anodised. Super nice stuff even today.
www.pinkbike.com/photo/17972210
The two minor things I wonder about:
1- The seat tube support beam there, I don't like. Maybe its needed but I like how those supports are gone on other bikes.
2- Is it possible to get a tapered headtube? Maybe I'm just trained to like the tapered headtube look.
1) yes, heaps of loads there if you want that low TT.
2) Yes, but it's a pain to mitre so why bother as a 44mm headtube does the same job and is easier (read slightly cheaper) to use.
Rare to see seat angle marketing fiction go the other way. Then again maybe it really is 73° and everyone else has fudged their numbers by 5° or so...
.
Marketing department dropped their donut and sprinted down the hall slid across a desk and hammered "7" "8" with everything they had.
J/k I'm sure it's just Mr White, and big kudos for a beautiful bike...and seat tube on trend.
Please explain how a 160mm, 29” bike with a mullet option flip chip and a trunnion mount shock is “out dated?”
That bike rad and unique. I could never afford it, but price should not be a negative when you’re talking about small custom frame building companies.