Why change? This is where things start to get slightly complex! In the past when deciding on a name I've simply thought of something that sounds good to me and fits in with my project in some way, then done a quick google search to see if there is someone else using the name for something similar, if not I've gone with that name. This approach has been fine up until now and Trademarking hadn't even entered my thoughts.... Turns out that the Vortex name has been used by another brand for a bike related product, on top of that that brand has taken the precaution to Trademark the name. This gives them the right to legally try to stop others using the same name for a similar product. So it's pretty clear, I needed to find another name! Easy, just think of something else? Yes and no..... I spent well over a week thinking about new names (we had something like 500 suggestions through comments on my social media posts Cheers everyone!) and came up with a list of 10 or so great ones. I checked them all for trademarks and narrowed down to just a couple of options. But how do I stop this problem arising again? Well, I could take out a trademark to protect my new name right? This costs money to do and if someone else started using my name I couldn't afford to actually defend my trademark! So trademarking for me seems pointless, but what if someone comes along and trademarks my new name after I've been using it for a while? In this case I would have some rights as long as I have proof of prior use. Exactly how it would play out if they decided to try to stop me using the name is unclear and I'd imagine would get complicated and stressful very quickly! All this is a lot of fuss and worry for a one man band who's only really interested in manufacturing great frames. So I'm cutting it out completely by taking a simple and obvious approach to naming my full suspension frames. From now onwards, they'll simply be designated their rear travel number as the name. I'm also going to be officially recording these names on my site (and I guess this blog post!) as unregistered trade marks... So '155' and also 'onefivefive' will be my unregistered trademarks for this frame from this date onwards. All this makes me realise why so many brands use numbering systems to name their products.
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In the first part of this brief history of Swarf full suspension frames we looked at the high pivot bikes, in this second part we are going to have a detailed look at the more recent short travel 29er frames. Part 2, the short travel 29ers Shortly after I made the decision to stop working on the Curve project I started messing about with 29 inch wheels. I really wanted to try them out so I made myself a hardtail. This bike was a revelation, it was nothing I expected it to be and everything I didn't expect. All the negative talk I'd heard about big wheels just fell by the wayside, it was fun, easy to corner, fine in the tight stuff and went uphill like a rocket. It was also fast. Even on choppy trails I was only marginally slower than on the Curve, despite feeling loads slower through the tricky stuff. Getting back on the Curve it was clear to see why, all of the sections you don't consider, the linking flat sections, that boggy short uphill, the short sections between corners, all these sections felt so slow and hard work on the full suss. The only downside to the hardtail was that it was punishing, riding rough stuff for any time was tiring and getting off line was scary! Every time I rode it, the thought was there, 'this would be amazing with a small amount of rear suspension'. So I sat down and started designing.  I approached the new design with a different mindset than I did with the Curve. As I was intending the bike to be simply a forgiving hardtail, I didn't worry about coming up with the most efficient suspension system and instead concentrated on simplicity and ease of manufacture. I ended up going with a single pivot design with a shock extension yolk to give a mildly progressive leverage rate curve rather than the linear or even regressive rate that you get with a more conventional single pivot layout.   The bike had the following geometry Head Angle 67 Seat angle 75.5 Chainstay 445mm Effective Top Tube 595mm BB drop 45mm It had 110mm of rear travel from a 200 x 51mm shock and the frame weighed 3.0kg without the shock. It was a great bike, rode really well and I was more than happy with the geometry. However I went and completely redesigned it! There were a few reasons for this
Contour 29er FS The new design addresses all of the issues I had with the original layout, using a rocker allowed the leverage rate to be tuned to something much more progressive, it freed up space on the downtube for a water bottle, it provides loads more stiffness to the back end and gave me that hardtail aesthetic. Winner! I decided to go for broke and use a flexing seat stay arrangement to drive the rocker to eliminate the need for a pivot at the dropout (I'd always wanted to do a flex stay design after I saw the Lahar DHV M9 years ago). Fortunately I was able to minimise the flex required by optimising the layout to the point where the stay flexes a total of 6mm (3mm up and 3mm down), the steel stays have no issue whatsoever with this small amount of flex. Frame weight 3.2kg without shock Rear Travel 115mm   I made two prototypes and we've been riding them for well over a year now, they've been absolutely faultless. I've done a second design loop with very minor changes and it's almost ready for production. The alterations were as follows
Carbon rocker When I removed the brace from the seatstays I perceived a reduction in stiffness. Instead of the brace taking the scissoring effect that side loads on the rear wheel create in the stays, the rocker now had to deal with these loads. At the rocker the two sides are trying to rotate in opposite directions, the 3 rods linking the rocker halves are not really the ideal engineering solution to this kind of torsional loading. Ideally the two halves of the rocker would be connected by a tube.
I spent ages trying to design a new aluminium rocker. I looked at a one piece machined part but the cost of manufacture was way too high, it's an incredibly complex part to machine to tight tolerances from a single piece of material. I also looked at a two piece aluminium design either bolted, welded or bonded together. Again the machining cost was looking to be the sticking point plus none of these seemed like the right solution. Bolting requires precise interference fits between the two halves to ensure the bolts don't become loaded in shear during use. Welding would have been a disaster, distortion and heat treatment worries being the main concerns. Bonding could have worked. I figured that instead of machining complex aluminium parts over and over again why not just machine moulds once and make the parts in carbon fibre? So that's what I did. The rocker was a two piece moulding, bonded together with aluminium bearing housings and threaded inserts also bonded in at the same time. The joint was then reinforced with further plies of carbon. It made no noticeable difference to the stiffness of the frame at all! Sometimes the less than ideal solution is good enough, and this was one of those cases! I swapped between the original rocker and the carbon one and couldn't detect any differences at all, both by flexing the frame by hand and during riding. The carbon rocker was way more involved to manufacture and it weighed the same as the aluminium one. With no real benefit I decided to just re-work the design of the aluminium rocker to improve it slightly and stick with that for production. There is a lot to be said for ordering machined parts and having them appear a few weeks later in a box ready to use! Testing
Out of all the one man band frame builders out there I reckon I spend more time than any personally testing my frames.. Two reasons for this 1, My years in the Aerospace industry means I'm paranoid about releasing something before it's ready and fully proven. 2, I love riding my bikes! I have ridden my own Contour prototype exclusively for well over a year now, it's covered 2500km and survived a Scottish winter. Bearing life has proven to be exceptional and the original set of pivot and linkage bearings lasted 2200km before I replaced them. The bearings were graunchy but there was no play in any of them. Dave has been riding the Large prototype for a month or so longer than mine and also has had no troubles at all. The frame has recently passed BS EN ISO 4210-2 which is the industry standard testing for mtb frames. 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.
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.
 Geo
 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!
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May 2020
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