OK, two things came together this week in a very interesting way: Firstly I’d been going through a list of peoples favourite books on bicycle design from a thread over on SingletrackWorld. I’d ordered up a copy of the most excellently titled ‘Bicycles and Tricycles: A Classic Treatise on Their Design and Construction’ by Archibald Sharp. Written in 1896 it was one of the first books to apply sound mechanical engineering principles to human powered transport. The introduction includes a great quote:
Accordingly, till a few years ago, a great variety of bicycles were on the market, many of them utterly wanting in scientific design. Out of these, the present-day rear-driving bicycle, with diamond-frame, extended wheel-base and long socket steering-head – the fittest – has survived. A better technical education on the part of bicycle manufacturers and their customers might have saved them a great amount of trouble and expense. Two or three years ago, when there seemed a chance of the dwarf front-driving bicycle coming into popular favour, the same variety in design of frame was to be seen; and even now with tandem bicycles there are many frames on the market which evince on the part of their designers utter ignorance of mechanical science. If the present work is the means of influencing makers, or purchasers, to such an extent as to make the manufacture and sale of such mechanical monstrosities in the future more difficult then it has been in the past, the author will regard his labours as having been entirely successful.
And you can’t say fairer than that! Mr Sharp’s goals came to mind when I spotted the following gem from the recent Eurobike show which immediately started my engineer spidey senses tingling; the Lauf Trail Race fork from Iceland:
There was just something I couldn’t put my finger on straight away… then I realised:
- The movement of the axle wasn’t guided in any way, the left and right hand ends could move independently of each other!
- The wheel is effectively connected to the frame by a spring with nothing else to guide it. The movement of the spring is partly contained in the vertical plane but will still have some compliance when ‘twisted’.
- Don’t get me started on damping and rebound tuning…
There’s no doubt that you’ll get some suspension action from having the wheel held on the parallelogram of leaf springs but I’d have huge concerns over torsional rigidity and the tracking of the steering. It’s interesting to note that they don’t have any independent reviews yet. Pro riders have done well using the fork, but then again you could put them on my nan’s old shopper and they’d still do well! I dropped Lauf a line over on their Facebook page:
Well, they seem happy but I’m still not convinced 😉 I’d only see it working if you’ve got a more standard mechanical parallelogram with both sides of the axle joined on a subframe – you could still use the leaf spring, although again I’m not sure how tuneable the damping would be.
If it’s an ultra lightweight linkage suspension fork you’re after then I guess it’s over to the german:A guys, although they can’t compete on the weight front (1.1kg vs 1kg for the Lauf, I’m rounding up in both cases). For the ultimate in weight saving you’re probably just better off with a rigid carbon fork!
The sad thing for me is that someone has clearly spent a lot of money developing this, including a very flash looking website. Although on the plus side you could probably power a small town from Archibald Sharp spinning in his grave… Speaking of which, what’s his book like?
Well I fancied giving the book a decent review so let’s save that for part two 😉
In the meantime you can read more about Lauf over here: http://www.laufforks.com/ (‘Shocking Design and Shocking Performance’ probably isn’t the best tagline in the world!).
And if you fancy some slightly mad linkage forks from german:A you can have a peek here: http://www.german-a.de/en/