BTR Fabrications: Push For The Pinner
Burf and Tam have moved on significantly since we last visited them in their humble shed in Littlehampton in 2013. Although the guys are still working on producing solid and tough handmade mountain bike frames in their new facility at The Bicycle Academy (and were centre-stage at the Bespoked show in London earlier this year), they're now branching out into producing their first production full suspension, go-anywhere mountain bike, the Pinner. The new bike has enduro-style geometry, trail bike travel and DH bike strength. We had the opportunity to ride one of their prototypes earlier this year and found it to be a real trail shredding machine, but the guys have has this and another prototype in development for 8 months, so their production version is a well-honed beast!
BTR Fabrications was set up in 2011 by Paul 'Burf' Burford and Tam Hamilton with what little money was in their back pockets. They were "two guys with a dream in a shed" working day jobs and building bikes in evenings and weekends. Since they started, they've had positive feedback from their customers from around the world - Japan, Australia, North America and Europe - and their frames have been featured in several mountain bike magazines and of course, the documentary about them first aired on Pinkbike last year. Not bad for two guys with a passion for mountain biking and the skills to build desirable frames!
 | We're really proud of our roots but wanted to step things up a notch so we've moved into a proper workshop and now spend almost all of our time working on BTR. Over the last few months we've been working on something really exciting - our first production full suspension frame. It's a go anywhere trail destroyer with enduro style geometry, trail bike travel and DH bike strength. A bike to take on an uplift without worrying about it breaking, that you can fly around a trail centre on, or just ride for hours with a smile on your face. It's the super fun full suspension bike we wished existed and daydream about riding, and it's called the Pinner. We've been testing 2 prototypes for the past 8 months, and are really happy with their performance, so now we've settled on the final design. - Burf and Tam, BTR Fabrications |
With only 15 days left of the campaign (ending 13th July 2014), the guys are on for a big push to get enough supporters around the world to bring this awesome frame to life. To explore the details of the campaign, read their FAQ or find out about the frame itself, head to the BTR Fabrications' Kickstarter campaign page: http://tiny.cc/pushforthepinner.
Geometry:
• 140mm rear travel
• 190 x 50 Cane Creek Double Barrel Air rear shock
• 3 sizes
• Reynolds 631 and 4130 seamless tubing
• Tapered seatstays and chainstays
• Sealed frame with no external breather holes
• Choice of colours
• Hollow aluminium rear axle
• 2 year limited warranty
• Crash replacement policy
Specifications:
• 26" wheels
• 140-160mm fork travel, 150mm optimal
• ZS44 head tube
• 31.6mm seat tube
• 73mm BB shell
• 142 x 12 dropouts
• I.S. rear disc brake mount
• ISCG05 chain device mount
• Max. 36t chainring
Optional Features:
• Integrated seat clamp
• Maxle rear axle
• No chain device mount
• Custom serial number
• Custom geometry
• Nukeproof Warhead headset
Author Info:
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You say that but I still prefer 26 over other wheel sizes (don't know about anyone else), and yeah, we do have a point to argue! A good example of this would be the Legoang world cup a few weeks back, like 90% of the field are on 650b's, yet Ratboy and Minnaar still took a 1-2 on 26's. People say 650's are better and roll quicker ect... and they might be in some circumstances but generally it's all down to the rider. The bike can only do so much.
Anyway, this bike looks cool, and different.
Who's winning the overall again? Oh yeah, Troy Brosnon on a 650 demo!
If you want bigger wheels, get a different bike, hahahahhahah
26inch wheels have been working fine and suit trails here in Japan greatly. (steep, rocky, twisty lines with jumps and drops)
The 140mm travel with the DB is most likely going to be very plush.
I first tried a shorter travel bottlerocket 140mm years ago and fell in love with the tight HT like geometry for DH riding with a 180mm fork.
I have a feeling this bike will have a similar ride to it but more suited for DH with its slacker head angle.
I guess it depends on your local trails on if you need or want more travel.
This might be a platform they will continue to harvest with more frames and maybe more travel in the future but, for now its a start for them as a beginning company with their own ingenious ideas, Keep it Simple! Brilliant!!
As for the looks of this bike, its awesome!
Smooth ridged lines that connect with practicality in good manner!!
I love the overall balance and build of the bike!
Its a simple single pivot thats linked for a smooth leverage ratio.
If there is peddle bob or what not you can easily dial it in with the CraneCreek BD shock.
It has a plethora of adjustments took things in proper running order to your liking!
Then the price is hight bit very competitive and especially for a handmade bike!
Pretty cool by my standards!
I hope they can generate enough support to keep this idea and push it into new realms in the future!
RideOn!
I dont think theres anything to prove on wheelsize. Bigger wheels wont fall in holes as much, but they will be heavier. Some people will prefer the feel of 26, some will prefer 650B...its not a matter of right or wrong.
You lose high density of structure defects and steel become soft.
Tempering always make steel softer and weaker (if it isn't HSS)
To make normal Cr-Mo steel stronger you must heat it to the temperature of allotropic transformation and then cool it fast.
www.youtube.com/watch?v=OQ5lVjYssko
Thanks for this you will get a lot of dyslocations and then you can do tempering to reduce hardness and turn dyslocations in borders of grains.
But if part has complicated shape (not shaft) it can crack or bend.
So it would be hard to make hardening of steel frame.
Aluminum is different, there is no allotropic transformation and you can do T6 treatment.
T6 is precipitation hardening like on the picture:
www.dh-zone.com/forum/download/file.php?id=7692&mode=view
These small grains of second phase bock movement of dyslocations.
Aluminum aloys are great materials for bike frames.
Zinc duralumin like 7075 T6 can have even 600N/mm^2.
Rm of 6061 T6 aluminum is 300 N/mm^2.
Density of this aluminum alloy is 2,7kg/dm^3
ratio of strength to density of 6061 T6: 300/2,7 =111,1
Rm of Cr-Mo 4130 steel in the heat zone will be much lower than 560 N/mm^2.
Density of this steel is 7,8kg/dm^3
ratio of strength to density of Cr-Mo 4130: 560/7,8=71,8
111,1>71,8 so aluminum > steel !!!!!!!!!!
So aluminum frame is 1,54x stronger when weight of frames is the same.
We can use 7075 duralumin and T6 treatment, then ratio of strength to density is abot over 200 which is almost 3x better than Cr-Mo steel.
That's why no big company won't try to make DH frame by Cr-Mo steel.
@guigui333 HSS is tool steel, there is a lot of carbon and alloys elements like V W Mo Co so this steel is very expensive.
Also thanks for high level of alloying elements this it is very hard machinable steel.
Another problem is fact that this steel is super hard to weld.
When you will go to allotropic transformation you dont have to use water to make hardening.
You will get out this steel from furnace and you will make hardaning in the atmospheric air.
After suitable forging, quenching and 3x aging this steel can work even in 600*C
There is martensitic transformation like in normal steels and precipitation hardening while tempering/aging.
After third aging in about 600*C you get small grains of alloyed ferrite with many microscopic carbides like V2C, VC, WC, FeCMoC W2CWC.
These microscopic carbides block movement of dyslocations so steel is super hard, but they also block recrystallization so high temperature will not make this steel soft.
Steels like this arent the best for frames because there is so many problems that frame would cost 100 000 and wouldnt be better than aluminum frames.
Steel has so big endurance because during manufacturing process is heat treated and forging many times.
It changes microstructure of steel that's why it has much bigger endurance than cast steel.
This is possible thanks to the machining of solid material in enough low temperature.
And now look at the welds, it just cast steel with huge grains and defects.
High energy while welding also change structure of steel in the heat zone.
Steel out there is very soft and plastic and thanks for this susceptible to intrusion and extrusion.
That's why fatigue strength of the heat zone can be even 150 MPa.
I'm going to problem of steel with tretment after welding.
To get enough big endurance steel must be hardened and tempered or cold formed.
You can't make heat tretment of frame to get enough big endurance in the weld and heat zone.
I think that except deformation and cracking you would have problem with oxidation during austenitizing because tubes are very tiny.
It could change 50% of tube in Fe2O3.
Another problem during austenitizing is creep of these tiny tubes.
With aluminum aloys there is no problems.
there is no allotropic transformation so while quenching there will be no martensitic transformation and no problems with deformation or cracks.
Quenching reduce endurance of aluminum but it get better during aging.
Thanks for that you will get big endurance in the heat zone and in the welds.
How about flexibility it isn't true that steel is more flexible,
Young's modulus of steel is 200 000 MPa
Young's modulus of aluminum is 70 000 MPa
You can say that steel frame is more flexible
That because steel frames tubes are very tiny so there is few times bigger tension than in very thick aluminum tubes.
steel is stiffer but the steel frame is less stiff
Aluminum alloys have many advantages that's why they replaced steel in the bicycle industry.
Haow about good steel on bike frames, I think that maraging steel could be good.
I don't know anything about weldability of this steel but I think it is passible.
Heat treatment of this steel is very similar to aluminum aloys.
The only difference is that during quenching there is allotropic transformation.
There is so much alloying elements that steel should be quench(hardened) in the air.
There is no carbon so martensite in this steel is very plastic and I think that frame wouldn't crack.
Then should be aging in much lower temperature, about 480-550*C.
After treatment these steels can get even over 2200 MPa
But this steel isn't cheap and give us ratio of strength to density only a bit higher than 7075 T6 duralumin.
And production of frames by 7075 is 20x cheaper.
There is allotropic transformation so in my opinion they can be hardened but hardening of so complicated shape can be impossible.
Also they are difficult to cold forming becaus they become too hard very fast so machined tubes must be annealed very often.
They are eays to weld so we can weld the frame and then make some annealing to reduce size of grains in the weld and heat zone, but I don't know how this annealing called in English.
Unfortunetely this annealing reduces the strength in cold formed tubes.
Two-phase titanium alloys could be better but they are heavier.
But they could be quenched and aged after welding.
The large is 20mm longer than the medium. Dont be fooled by the short TT! thats just because the seat angle is steep for better weight distribution on climbs. Burf is 6'2" and just fine on the large, hes even surprisingly comfortable on the medium. Dont forget we can do custom reach, which is FREE if you buy a Pinner through our kickstarter campaign! www.tiny.cc/pushforthepinner
sounds like they've designed the perfect bike for the southcoasts trails!
Frame looks absolutely awesome! Would love to have the spare pennies to be able to indulge.
The trails in the video weren't close to Bath by any chance?
Best of luck for the new frame and the coming years as the company undoubtedly grows!
@chmod, your tubing is cut already...should be starting welding on monday!
Steel is a great material for bicycle production. However, I understand that mass producing high quality steel frames is expensive compared to ally, and it can't command the high prices of carbon.
But I'm an aerospace research engineer specialising in carbon fibre, but steel is the material for me. See here for my homemade steel frame; www.pinkbike.com/photo/10520089
I hoping to come over to Frome for a Fillet Brazing Masterclass sometime soon. Be good to come and have a chat with you BTR chaps.
I want one!!
She Still rides a- mazing too! (Just the idler wheel is a little bit worn, so could do with a new one...)
I'll pm you, I would love some details on maybe getting one.....
I will be building a FS over the next couple of years (to late for the quickstart) and I'm a bit of a Cotic fan, but is there any reason I should be considering this as well?
I shall say nothing more.......
In my eyes nice looking frame which does it all not many bike out there which can say that gracefully
An why is it people allways go on about wheel size
Our sizing is here: www.btr-fabrications.com/support-and-faq
If in doubt, drop us an email with your measurements and preferences, and we'll be happy to help you decide; www.btr-fabrications.com/contact
We can do custom sizing too...
853 and 631 are the same material; 853 is heat treated, 631 isnt.
The critical areas on a frame made from either material will be in or around the welds. Given that the material is chemically identical, the filler which is best for 853 is the same for 631, so theres no hope of gaining an advantage there- this leaves the 'heat affected zone' (thats the area in the tube right next to the weld bead) as the critical section.
The material in the heat affected zone will have been heated to well above the transformation temperature during welding, and then cooled with the rest of the weld. This does a pretty good job of erasing any previous heat treatment in that area of the tube. So even on an 853 tube, there will be a small band next to every weld where it is no stronger than a 631 tube.
Because of 853's higher strength, the tubes are generally made with thinner walls than 631- this is great for light weight, and strength isnt a problem away from the weld areas, but its not good for stiffness.
853 is also a lot less ductile than 631 (9% instead of 11% elongation at break, IIRC), so if something does go wrong 853 will give you less warning than 631.
All of these factors combined lead us to select 631 over 853 for all of our current frames. When we make an XC frame it may well be a different story though, with weight being a greater issue, and a lower demand on outright strength and toughness.
Frame weight?
Does it fit a sealed drive?
3.7kg, not including shock (prototype build weighs 33lb with old pikes, tubes, bash ring, etc)
www.btr-fabrications.com/support-and-faq/pinner-faq
Thanks for your email too
www.btr-fabrications.com/support-and-faq/pinner-faq/#question29
- personally I prefer the clean lines of steal tubing which also allow the frame to have smaller diameter tubing. Early 90s steel frames are awesome (BMW, spooky, evil)....
That being said, The Pinner looks awesome - I'd buy it if I didn't already have 5 bikes
Ov3rr1d3 I don't really know what you're questioning me about? The frame is too complex (aesthetic) for my taste. I'm very much in the Ramms camp of 'good design is as little design as possible'. There are gussets all over and little bits cut out here there and everywhere and the shock is a weird looking thing too. To me, it's just not a pretty bike.
Ledude You say you love 'clean crisp lines of steel' then say you don't like hydroform, but hydroform is essentially all about the clean crisp sweeping profiles and the lines it creates. I thought you would be a hydro advocate!
The Pinner is f'en gorgeous - way more straightforward than a lot of other frames out there...'less is more'.
The TT is short because of the steep seat angle; the steep seat angle gives you much better weight distribution when climbing in the saddle. The reach is what you will feel when out of the saddle.
Opinions are funny things. I agree with you bud. The thing looks killer and while I'd want a 26" version anyway, if the demand is there for a 650 or a 29er, why not both? Cray cray!
Design costs are trumped by demand. If there's a demand, and I think people would want it, that's the most important.
It's kinda sad how this nonsense has gone full circle. At first, the big hype was 650 and all that good rollover. Then people were thinking "Hey why not just do a short stay 29er?" So companies did, and people loved them. Then we went with "Oh if short is best, why not a short 26?" So that's what's getting big right now.
No standard trumps the other. They all have situations where they excell. I enjoy 26 for playing, but this 650b/29er hate lately is just such a bloody pisstake. Stop letting trends define how you build you bike, don't build a 29er cause someone told you 26 was lame. Don't build a 26 because someone told you they are the only way to have fun. Go ride and build bikes, find what works for you.
Sheeple these days.