Modern Clelands

[GeoffApps]

Yes.
It is thought by some that the cross-frame idea had been around for a while before Raleigh popularised the concept.
It's quite a useful design because it allows the use of thinner tubes whilst maintaining stiffness and strength.
As far as the Cleland concept is concerned, the cross-frame can provide a long headstock with a low step-over.
I'm just waiting until I come up on a scratch card...

 

[GrahamJohnWallace]

The latest Cleland news is that some bio-mechanical academics in Belgium have concluded that in theory non-round chain-ring with off-set cranks and combined with off-axis swing pedals will develop 5.3% more power than standard pedals and round chain-rings.. A combination that Geoff Apps has been using on his Cleland TT for the last 3 years. Of course the road-racers need to be quick in utilizing this technology before the UCI ban it. :facepalm:

Or perhaps the bike industry will wait 30 years before adopting this idea, like they did with 700c wheeled mountain bikes?

Here is a link to the research paper about theoretical gains relating to the use of non-round chain-ring with off-set cranks and combined with off-axis swing pedals:
http://www.noncircularchainring.be/pdf/ ... 0Pedal.pdf

They have also published detailed research on the relative efficiency gains of different shapes of non-round chain-rings. In this they conclude that using the optimal crank off-set relative to the major/minor axis is crucial in the bio-mechanics of the extracting extra power from a riders legs. Interestingly it turns out that nearly all manufacturers of non-round chain-rings did not off-set the cranks though some have started doing so since this research was published in 2012. Chris Bell of Highpath Engineering has always off-set his chain-ring exactly as the research recommends with the exact angle being determined by relative position riders bottom / centre of gravity.

For a detailed explanation of what is meant by crank off-set, look up "crank retardation" in the technical information section for oval chain-rings at:
http://www.highpath.net/

For the latest research into the dead-spot see:
http://www.noncircularchainring.be/pdf/ ... Centre.pdf

 

[Chopper the ex Copper]

!!!! THREAD RESSURECTION WARNING !!!!

My lust for Cleland and Highpath is no secret, and I've recently resumed work on my own Cleland inspired machine. Does anyone else own, or maybe building their own Cleland-ish? I be interested to see any pictures and discuss ideas.

 

[GrahamJohnWallace]

Re:

Hi Chopper1192,
Geoff Apps is running a blog about his latest build here:
http://crosscountrycycle.wordpress.com/

I am also in the early stages of building a Rolhoff hub geared Cleland, based on an On-One Scandal 29er frame. It will have front suspension and a dropper/Thudbuster suspension seat post. I will probably use 650b wheels in the winter in order to get a little extra mud clearance between the forks, frame and the tyres.

I have recently been testing some Schwalbe tyres fitted with a reinforced sidewall system they call 'Snakeskin'. So far there is no sign of the sidewall stretching or ripping that is associated with running lightweight tyres well below their recommended pressures.

No pictures yet I'm afraid. Just a growing pile of parts.

Meanwhile a mechanical analysis of Geoff's drop pedal system implies that there is a pedaling dead-spot removal characteristic at work. The mechanism for this is quite simple, in that under load, the pedal swings slightly forward in front of the dead-spot. This makes it a tad easier and quicker to get the next power stroke underway.

 

[Chopper the ex Copper]

Is there any word from Geoff yet re plans to sell swing pedals?

 

[GrahamJohnWallace]

Is there any word from Geoff yet re plans to sell swing pedals?

Not that I know of.
They are one of those products where people are skeptical because they think that if they worked so well, then everybody would be using them. Having tried them and studied the research, I personally think that it's an excellent design that one day could well become popular.

The only problem is that you need a bicycle with a bottom bracket height that is 30mm higher than normal. Put these on a standard frame and the pedals would too easily ground.

 

[mattr]

FWIW, swing pedals have been around for an age, they keep dying a death as the bearings don't last when you press on (nice lever pulling on a too short an axle stub) they also push the pedals outboard, so don't suit everyone. (And to make them more durable, you need to push them further outboard or use massive bearings!) Might work well with a lower duty cycle, or better bearing selection, but there will still be a limit to their durability.

Non-round rings aren't exactly new either, despite shimanos attempts at putting everyone off....... they've got quite a following lately (last 6 or 7 years?) on the road scene.

 

[GrahamJohnWallace]

FWIW, swing pedals have been around for an age, they keep dying a death as the bearings don't last when you press on (nice lever pulling on a too short an axle stub) they also push the pedals outboard, so don't suit everyone. (And to make them more durable, you need to push them further outboard or use massive bearings!) Might work well with a lower duty cycle, or better bearing selection, but there will still be a limit to their durability.

All you say is true but these pitfalls can be avoided with a little bit of first principle engineering. Even the problem of the bearing thickness pushing the pedals outboard can be resolved by building the bearing inside the crank arm.

The big problem from a product design point of view is that you need a specialist frame to accommodate the optimum 30 minute drop that has been calculated by bio-mechanical analysis.

Non-round rings aren't exactly new either, despite shimanos attempts at putting everyone off....... they've got quite a following lately (last 6 or 7 years?) on the road scene.

Again true. Though it is interesting that all but one of the makers of such rings didn't calculate the correct position of the dead-spot but assumed it to be when the crank is vertical. Only when the academics pointed out this error did companies start to retard the crank relative to the major axis of the chain-ring. This is because the pedaling force of the leg has a horizontal component caused by the rider sitting behind the pedal axis.

I am concerned that studies into the effectiveness of non-round chain-rings invariably base their studies on a cadence of 90 rpm and focus on how much power is generated.
I would personally be more interested in seeing the results of low cadence studies that focus on bio-mechanical efficiency and effects on fatigue. Especially when hill climbing.
The reason being that at high cadences you can only spin slightly non-round chain-rings smoothly. With an extremely elliptical rings spun at high cadences it is also difficult or even impossible to keep up with the freewheel. So very elliptical chain-rings are best suited to slower cadences. Used this way they make hill climbing and riding into strong headwinds noticeably less tiring.

On the topic of these ideas "being around for an age", you are of course correct. But unfortunately, I can't discus the new ideas that are currently being prototyped by Cleland just in case they lead on to patent applications.

 

[02gf74]

Non-round rings aren't exactly new either, despite shimanos attempts at putting everyone off....... they've got quite a following lately (last 6 or 7 years?) on the road scene.

if the web is to be believed ....

Although Oval chainrings were invented in the 1890's,

 

[CTK]

Re:

Are there any frames (retro or modern) which are suited to a Cleland type build?