Swarf Full Suspension, a brief history.... Part 1

Although Swarf is best know for making custom hardtail frames, we've been working on full suspension projects since day one. In this two part blog we're going to jump in and have a look at those early bikes. Prepare to geek out! 

​Part 1, the high pivot and idler frames, Bedfo's Super Bike and the Curve

​Bedfo's Super Bike​

​Back in the day I had a Balfa BB7 DH bike which I really liked. The high pivot layout gave it an amazing magic carpet ride, the roots, rocks and big hits just vanished underneath you. I often wondered how a lighter shorter travel version would ride, so in 2010 I set about finding out. The pictured bike is what I came up with, it's basically the BB7 layout, slimmed down and reworked for 150mm travel.  It featured a fillet brazed 4130 steel front end and a full carbon swingarm. Frame weight was in the region of 8.5Lbs.

This bike rode really well. It was an easy bike to ride, you just jumped on and immediately felt at home, I think this was partly to do with the super supple suspension action of the high pivot, and partly due to the slightly quirky geometry. It had long chainstays (445mm that grew to something like 480mm at full travel) and a short front end, this put lots of weight into the front wheel and is what I attribute to the easy going nature it had about it. We rode this thing for 3 years and it was faultless, it covered around 3500 miles and spent 15 weeks out in the alps..... 

Geek stats
Head angle 65 (I think)
cant remember seat angle
Chainstays 445
ETT something like 560mm
Reach measurements didn't exist at this time!
BB height 317mm
160mm fork and 150mm rear travel
Swingarm, full carbon moulded over a foam core, no moulds used and no bonded metal inserts
Leverage ratio, Virtually linear 3.1 - 3.0

​I've seen claims from a couple of companies recently that they have designed the worlds first high pivot trail bike.... Well, I finished this bike in 2011 and I was by no means the first. There was a dude in NZ called Rosco, he also made a short travel Balfa but used a Balfa swingarm on a new mainframe, Zerode had a one off carbon trail version of their DH bike. Corsair had a high Pivot bike actually in production around the same time, the Marque. This bike was way ahead of it's time, sadly it was dogged with technical issues. They tried to make it compatible with a 2x front set up with idler and derailleur, it just didn't work. That same bike with a modern 1x set up would be amazing, it still looks good today.

2013 Curve

I quickly realised that there were lots of aspects of the original frame that would have to change if I wanted to market the bike.

• average leverage rate was a bit high
• geometry needed to be worked on
• it needed to look a lot better!

​
So, I sat down and designed a new frame, the Curve....

The frame retained the high pivot and idler plus the steel and carbon construction, everything else was totally different. 

• Travel 130mm or 150mm depending on shock (200 x 51 = 130, 200 x 57 = 150)
• The average Leverage rate was lower and instead of the linear curve it had a fairly progressive curve ( I worked with Cane Creek on this)
• flip chip geo adjustment
• modular dropouts to accommodate either 135mm qr or 142 x 12 rear axles
• Fully moulded carbon swingarm (I machined the aluminium moulds and made all bladders and swingarms in my shed, just like Hope are doing ;-) Again no bonded metallic inserts used anywhere in the swingarm.
• Swingarm weight 600g
• Reynolds 853 DZB butted tubeset front end
• Linkage running on polymer bushes
• Compatible with both 26" or 650b wheels

​Geo

• ​Head angle (low position) 65.5
• Seat angle (Low position) 75
• BB drop 20mm
• Chainstay length 430mm

The bikes rode amazingly well and proved to be super durable. The suspension action was now even more refined, small chatter just doesn't exist on this frame and big compressions now were easier to deal with due to the progressive leverage rate curve.

However the frames were not without issues, the biggest being that the swingarm was a total ordeal to manufacture (I think I averaged 40-50 hrs for each one!). Whilst I have the capability to design and manufacture everything required to make a carbon swingarm, I just don't have the resources to be able to put a carbon swingarm into production. Not only did I have lots of troubles actually making the parts (they're incredibly complex) I also had worries over the repeatability of what I was doing. There were so many variables that were out of my control, mainly due to the cure cycles (I was using wet lay up as that's what I was confident working with at the time) that I couldn't confidently know that each one was exactly the same. Without truly knowing what you have it's impossible to offer any kind of warranty. As it turns out I needn't have worried, all 7 Curve frames that I made are all still going strong as far as I know.

There were other minor issues with the frame, the flip chips worked loose and had to be bonded, and using bushes on the linkage was a bad move. Technically they should be better than bearings for dealing with small movements at high loads, the reality is that once they are slightly worn, dirt gets in and accelerates the wear. This wouldn't be a big deal if it was just the polymer bush that wore out, sadly the stainless steel rods wear as fast as the bushes and the whole lot requires replacing! We tried various rod materials with similar results. Lots of lessons learnt and all have been applied to my latest frames.

In part two we'll have a detailed look at the development stages of the new Contour 29er frame. Cheers!