Hello all ~ especially Ned & Graham ~
It is true that the Cleland is not remarkably dissimilar to present-day mountain bike frame designs. However, it was thought rediculous back in 1979 - 1985. The general trend in mountain bike frame design has been toward the Cleland and away from the Ritchy.
The characteristics of the Cleland design can be refined by some quite subtle distinctions in frame geometry, but these are not critical to the concept.
The Clelandale, for example, utilised a stock Beast of the East Frame with Project 2 forks. To gain tyre clearance (and to find out how they would perform) it was fitted with 37-590 Hakkapeliitta tyres on 18mm Sun Metal rims. I played around with mudguard fitting, and had a pair of those special 'limited edition' Sturmey Archer hubbies. The machine worked fine, considering the design compromises made.
It was definitely a Cleland design.
The Aventura II is a utilitarian beast, built as cheaply as possible from stock bought-in components, with a fair amount of work in PhotoShop with carefully taken photos of the various components, bringing them together in a multi-layered full-scale tif, and then checking dimensions, angles and fitting.
This is because another ethos of the design is that Cleland is not exotica; it's a down-to-earth practical and pragmatic design.
In my many years of research into bicycle design I have discovered one very important factor, which must be born in mind when designing a bicycle.
It is this: The human ability to ride a bicycle is very adaptable. This means that, within a certain range, there remains a high level of variability in the design of what can be ridden successfully. Well prepared and in the hands of a skilled rider, a bicycle of modest quality and conventional design can perform reasonably well. The ability to ride a particular design of bike successfully can also be determined by the amount of money parted with at point of purchase, and the extent to which the owner has extolled it virtues to his mates.
But that a bicycle performs well is as much to do with the rider as the bicycle itself. However, we must take into account the efficiency of the rider and bicycle relationship, and in this area, quite subtle differences can begin to pay dividends over an extended period of riding.
For example: Cable operated rim brakes require hand pressure to make them operate; the harder one pulls on the lever, the greater the braking effect.
Therefore, hand fatigue will be a factor after a ride of several hours. Hydraulically operated disc brake systems do not require hand pressure to make them work, they simply require the brake lever to be moved to a certain degree to achieved the required braking effect.
After one or two hours of riding, there will probably be no noticable difference between the two. But after three or four hours, and the cable-operated rim brake rider will be beginning to feel the effects on wrists and fingers. Five or six hours, and the difference will be significant.
Is this important? Does anyone care? Well probably not much. People spend their hard-earned money on the bike they choose, and ride it. It rode fine on the test ride, so there you are. How do we, as individuals, know how much pain and fatigue other riders are suffering? One rider may be very happy indeed to end a ride feeling like he or she has done several rounds with a boxing champion; another may find this detracts from the pleasure of riding.
These considerations of efficiency ~ how tired and/or damaged one feels at the end of a ride ~ are prerequisite factors I incorporate into any Cleland design. They are not at all obvious when looking at a photograph or drawing. In fact you can only become aware of them after several hours in the saddle; and only then if you know what it's like to ride another design of bicycle over an equivalent distance.
So, I'm getting tired now, and so may you, too; it's time to wind this little ramble up with a neat conclusion: The Cleland design is more a principle than a set of strict criteria ~ don't get too enmeshed in the minutia of angles and dimensions; provided the machine functions efficiently, or at least, more efficiently than anything else ~ and, by the way, if you haven't got it yet, the efficiency is not mechanical efficiency so much as rider efficiency ~ then it achieves its aim.
Coo, I still haven't done steering geometry and centre of gravity yet.
Hmmm, what have I got myself into?...
