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
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
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!
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.....
Head angle 65 (I think)
cant remember seat angle
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.
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.
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 issue 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!
Last August I went on a week away in the highlands of Scotland with Go-where Scotland. In the emails back and forth leading up to the trip, Andy (Go-where's main man) jokingly mentioned that I should have a chat to Huw (our guide for the week) as he's a connoisseur of the bike and also partial to some pretty amazing adventures on two wheels, Andy reckoned if I played it right I might get a sale!
Well that's pretty much what happened, turned out that Huw's girlfriend, Annie is as mad for all things cycling as he is and she has a soft spot for a nice custom steel frame (she's a class lady!). Huw and Annie's outlook on mountain biking is a good one, they're more concerned about fun, durability and practicality than fancy bling.... With that in mind, one afternoon with bikes on our backs halfway up a heather covered highland mountainside, I offered Huw an option . How about I make a couple of TIG welded bikepacking frames at a reduced price in order for me to hone my developing TIG skills.... Well he obviously took the offer seriously and after a few months the email came through, and we started planning the frames. This is what we ended up with
B+/ 29er compatible
2.4" 29er tyre clearance, 3.0" B+ tyre clearance
100mm suspension fork or rigid fork
148 boost rear axle and crankset
30.9 seat tube
44mm head tube
Lots of bosses for bottle cages in various places
Powdercoat finish (Huw's RAL5021, Annies RAL4010)
68.5 degree head angle
74 degree seat angle
60mm bb drop
We had an ambitious plan to have the bikes done for the Strathpuffer in Jan (in which Annie finished 1st and Huw finished 2nd in their respective solo categories!), sadly some issues with powdercoating prevented this from happening. Various other holds up's have meant that the bikes have only just been built up and ridden. They look amazing and the timing is perfect for some Scottish summer adventures... Hopefully we'll be seeing plenty of photos with them in some wild surroundings.
Check out Huw's antics on Instagram @topofests
Annie has some truly stunning images on her Instagram feed @a_girl_outside
Guided mtb holiday in the Scottish highlands
We've grown to love a good guided holiday. If we're travelling for the best part of a day to get to our riding destination, we don't want to be hunting for the good stuff when we get there! Guided trips take away the head scratching and map pondering to get you straight to the stuff you'll never find on your own.
This trip was exceptional, right from the moment we met Andy and the rest of his team it was like being away riding with your mates. In my book this is how it should be! A week of top banter, top trails and top weather made this one to remember. I'm not going to go into detail of each days riding, I'll just let the pictures sum up the holiday.
Early last year Cy from Cotic sent me an email asking if I wanted to help him out with some work to investigate the feasibility of a carbon back end for his Rocket full suspension design. Obviously I jumped at the chance and have been working with him on and off since then. I've been involved in all aspects of this rear end from design through to prototyping. I ended up making a one off carbon swingarm prototype, both for testing and to get a feel for the required layup. The proto has been ridden thoroughly and although various aspect can be improved has proven really successful.
Cy has also been working with Scottish frame builder Shand, looking at the steel front end. One of the prototype steel front ends has been assembled onto my prototype swingarm to give a one off UK made bike. This bike is being displayed at this years Bespoked UKHMBS. Currently this is just a feasibility study, the only person who knows if this will progress further is Cy himself.
Curve Frame for sale!
Here's a really rare opportunity! Adam is selling his Curve frame. Its the last one I made (No 7). It comes with Shock, headset and rear axle, £950. Please direct any interest to Adam, mailto:email@example.com 07815034289 (not to me!)
Swarf Curve Frame with Cane Creek inline shock (set to 150mm travel) and ceramic bearing headset. The lower handmade carbon chain retainer is included too.
Painted by Fat Creations in candy Blue with white pearlescent fleck.
Reynolds steel front and carbon rear (completely handmade)
Roughly a medium frame but with extended reach, similar to early forward geometry bikes
Would suit anyone between 5ft5 and 5ft11 (i'm 5ft8 on a good day!)
425mm seat tube
337mm bb height (150mm fork)
65 deg head angle (150mm fork)
30.9 seat tube
- Built by Adrian November 2014 and used in spurts ever since (either side of testing other bikes).
- Meticulously maintained, regular bush and bearing change - frame will come with new set all round
- 142x12 bolt through (just look at those dropouts!!)
- 44 mm head tube for all fork combos
- Paint is super thick and durable but there are quite a few paint chips to rear swingarm and around main pivot.
Also some paint wear on bb shell and where hoses attach (all in pics). Please note, none of these are through the primer, Fat Creations paint system is done to last.
Adrian keeps all spares for these frames so that is never a problem (bushes, rods, bearings, dropouts etc)
These frames were over £2000 when new due to the hours of meticulous labour that went into making them.
With the paint chips and rub, I'm asking for a very reasonable £950.
Frame is in Bristol, viewing welcomed, can be brought to Dorset for the right deal.
Alex's 27.5 Splatter Spline wins Pinkbikes reader poll , 'The Sexiest AM/FR/Enduro Hardtail of 2015'!
Alex had a really clear vision of what he wanted when he came to me to have a custom geometry Spline made, the frame turned out to be a winner and with his select build the bike is awesome. Here's his story of the journey of having a custom Swarf frame plus some detail of his final build (including an interesting ghetto pro-core system!). Words and Pictures by Alex Klimow
The idea behind this bike was to take the fit of my previous bike i.e. the distance between the bars and the seat and exaggerate everything else, without going too far.
My previous big bike was a Ragley Bagger 288 on which I used a 70mm stem and 750mm bars. The seating position was generally alright, but the 70mm stem was inappropriate in my mind.
So I started looking around, 650b became a thing, I read a lot about Forward Geometry and what Chris Porter thinks about bicycle geometry and I didn't find anything that combined everything I now believed to be important.
A custom frame was the only solution to my 'problem'.
I contacted a few frame builders but wasn't thrilled with their responses and I kind of resigned. Then one day my good friend Franzi told me she was getting a steel full suspension frame built by a somewhat nerdy British bloke and that I should ask him. So I did.
The correspondence was everything I was hoping for. No immediate 'Yeah, I'll do it! Give me some money.', no 'Why would you want such a long reach?', no 'Fillet-brazing is for grandads! TIG welding is for men!' but a healthy discussion with countless emails* crunching numbers, discussing manufacturing techniques and evaluating subjectivities.
It took us a good four months to settle on the final geometry. January 2015 I think it was when I couldn't think of anything to be changed.
Compared to the Bagger I wanted the seat angle to be steeper, head angle slacker, bottom bracket lower and the whole bike to be longer. All using a 150mm fork and a 50mm stem.
The final geometry was as follows:
(sagged, as anything else doesn't really make sense on a hardtail)
For reference, I'm 1,77m tall.
66° head angle
75.5° seat angle
430mm seat tube
305mm BB height
It worked out great and the craftsmanship is excellent. I was and still am over the moon.
Especially with the frame being painted by Fatcreation's Alistair McLean.
The inspiration for this paintwork was an early nineties Kuwahara and Geoff Gulevich's prototype Rocky Mountain DH bike from 2014, I think.
I took the bike on two trips to the alps so far, did a lot of local riding and a bit of racing (one enduro event). And I can now tell you that a frame with this much reach is not to be trifled with. I think I slowly but surely got the hang of it now.
It definitely has huge benefits, but also its downsides. They are manageable, though.
The Spline's standard geometry should be more approachable.
Somewhere along the line I asked the guys at BTR for advice on the geometry and Tam generally agreed with it, but suggested to reduce the fork travel to 120mm. I was pleased with his response but thought to myself 'What does he know about fork travel? I'll stick with 150mm.'
It might surprise you then that I recently reduced the fork travel to 130mm. Which makes the bike handle miles better than before.
I also asked Brant Richards for advice and exchanged a few emails with him. Thanks again!
The build is more sturdy than light weight and with a proper mix of Shimano XT and Zee parts. I've got XT brake levers, Zee calipers, an XT rear mech body and a Zee cage. The cassette is a 9speed one. To make that work with the Shadow+ derailleur you need a 9speed Sram shifter and clamp a 6mm spacer under the gear cable.
Looking closely at the rear wheel you can spot a second valve stem, too. I put a 700c tubular tyre in there to never get a pinch flat again. I got a lot. Even with tubeless setup.
A lot of guys on mtb-news.de do this, which is where I got the idea and it's a great alternative to that Schwalbe Procore kit. You do need to drill another hole in the rim, but the rest is a doddle. And it's a LOT cheaper.
Ok, getting the tyre off the rim isn't a doddle but it's still well worth it.
That's about it. I hope you like the bike and give Adrian a call in case you want a new bike.
*read: more than 200''
Its the new year and we are clearing out some parts that are surplus to requirements. First come first served on these bits.
Please email if you are interested in anything mailto:firstname.lastname@example.org
Cane Creek Double Barrel Air CS Shocks, £275 each inc p&p
200 x 50 with 35mm spacing mounting hardware, including all documents and allen key SOLD!
200 x 57 with 35mm spacing mounting hardware, including all documents and allen key SOLD!
Both Shocks are in new condition, no marks or scratches anywhere. Both have seen less than 300 miles use.
WTB Trailblazer tyres £75 the pair inc p&p SOLD!
2.8" 27.5 TCS Light folding bead
Virtually new condition, they have done around 30 miles total off road, they were mounted tubeless so there are traces of sealant around the bead.
Retail at £45 each
X Fusion Hilo SL Remote Dropper Post, £160 Including p&p SOLD!
Brand new in box
30.9 diameter, 125mm Drop, bar mounted lever
Gravity Light 777mm flat handlebar, £10 inc p&p SOLD!
Silver, 777 mm wide, 0 rise, 10 degree backsweep, 4 degree upsweep, 31.8 clamping diameter
These are unused and uncut.
Odds and ends
1 x 2014 Rockshox Reba service kit, £10 posted
1 x Maxxis Beaver 29" x 2.1" tyre, 50 miles use, £10 posted
1 x Continental Mountain King 29 x 2.2", 20 miles use, £10 posted
2 x Rockshox shock pumps, nearly new condition £7.50 each inc postage
4 Pairs Goodrich Blue Resin Brake pads, fits the older XT brakes and some Hope brakes £15 the lot
Please check images below to be sure they are the correct pads for your brakes
4 Pairs Superstar Organic Brake pads, fits older Saint and Deore brakes £10 for the lot
Please check images below to be sure they are the correct pads for your brakes
Swarf owner Ian Stott raced his bike at the Belgium Singlespeed Champs in September, he's just sent over this great report of his experience, it sounds like a lot of fun! All photos are from third parties at the event.
More of a singlespeed festival than a bike race, SSBE was held over a weekend in September in Hamme, Northern Belgium. The Saturday started out with a hangover (from the Friday night arrival drinks) which blended nicely into a 30k ride from the event site taking in the local woodland trails. At least 50+ singlespeeders being led by a couple of locals around their trails, with a beer and BBQ stop about 3/4's of the way round. In the UK i couldn't help but think we would have been seen as a nuisance, but in Belgium we were treated with respect and smiles by both car drivers and dog walkers alike. This was the first time i had really ridden the Swarf on tight, fairly flat, woodland trails. It was fantastic. This bike seems to corner with far more grip than my old one which had exactly the same build. It also popped and jumped off the roots as easily as i could have hoped.
There has been a lot of hype over the last year or so about the new B+ tyre standard (27.5 Plus or 650B+, call them what you will) it seems that they'll be everywhere for 2016 with many manufacturers making plus size models. So I thought it about time to get some tyres to try them out to find out what it's all about. This quick blog will give you my thoughts and first impressions. This is all personal opinion so please take from this what you will!!
WTB were the first to produce a B+ option with the 2.8" Trailblazer and massive 45mm scraper rim. The initial talk was that the big tyre on a 650B rim was slightly smaller than a standard 29er tyre in diameter but obviously wider. This meant that they would fit into many existing 29er frames with the promise of improved grip and reduced trail chatter due to the ability to run lower pressure. Sounded great to me especially for use on the Spline 29 hardtail, could be a fun option.. So I ordered up a set of the Trailblazers from Charlie the Bike Monger and set about playing about with them!
My first thought after mounting the tyres was they're not that big at all! I wanted to do as many will, and that is to mount them to existing wheels that they already own, in this case a set of Stans Arch rims. Obviously these are very much narrower than the 45mm Scrapers that WTB designed the tyre to work with. Below are the measurements for my rim/tyre combination and a couple of non plus sized tyres for comparison.
WTB Trailblazer 2.8 on 650B Stans Arch - Width 62mm, diameter 716mm
On One Chunky Monkey 2.35 on Light Bicycle 28mm internal 29er - Width 60mm, diameter 740mm
Schwalbe Hans Dampf 2.25 on 650B Stans Arch - Width 57mm, diameter 700mm
This was a bit of an eye opener for me! They're actually closer to a 650B wheel than they are a 29er and on these rims they're not much wider than the On One tyre I'm using on my 29er currently. Sure, the wide rims would give extra width and volume but I cant see the diameter increasing by much more than a few mm. They'll end up pretty much bang in the middle of 650B and 29 sizes.
The wheels were fitted into a Spline 29 hard-tail without issue. The clearances to the fork are getting a little tight on the sidewalls but perfectly acceptable, with the wide rims this may be more of an issue. We tried them in both Rockshox Reba and Marzocchi 320 29er forks with pretty much identical clearances.
One side note here, they actually fit really nicely into Rockshox 650B forks and I've been using a Trailblazer on my 650B trail bike as a front tyre!
Riding, the fun part!
Initial impressions are good for general use. They roll really well, seem nicely grippy considering the fairly modest tread pattern and indeed the larger volume does take out some of the trail chatter. When you push them harder you begin to find the limitations of this tyre/rim combination. I tried running low pressure (18psi) but frankly it just didn't work, they were squirming about a lot and you could actually feel the sidewalls creasing. I ended up running them at much the same pressure as I do my normal 29er wheels and they still felt a bit squirmy when pushed hard.
So then, this all leaves me a bit confused! Yes they fit into a 29er frame, yes they're slightly higher volume yes they roll really nicely and seem grippy. On the downside, they're not that wide and feel a little unpredictable (when really pushed), mainly I'm sure, due to the narrow rims I used. However, on wider rims I'm nervous of that tyre clearance on a standard 29er fork will be getting quite tight.....
I don't feel that I have truly experienced plus size yet, more experimentation is needed, will try and get them fitted to some 35mm rims and see how that plays out. Stay tuned!!
Check out this link for an interesting read on why wide tyres roll nicely off-road