Wednesday, March 4, 2009

Aluminum and steel cranks.

Steve Saines, who regularly comments on my posts, mentioned the elegance of the old steel Stronglight cranks on my Cinelli. I don’t think that there is any doubt that the old cranks were much nicer looking than those of today; however steel cranks have two things going against them: first they are quite heavy, about 50% heavier than a similar alloy one and secondly they wear much faster than the alloy equivalents. As odd as it seems the square tapered hole, which mates with the b/b axle, wears very quickly. The cranks on the Cinelli (mentioned in my last post) have worn so much that a have had to grind about 5mm off the end of the axle to allow the cranks to pull further on. The reason is, I believe, that the aluminum cranks mate much tighter onto the steel axle, the steel bedding into the aluminum eliminating any chance of play. This doesn’t happen with the steel cranks and any slight difference in the mating of the two will quickly develop into wear.
The problem was also common with other steel cotterless cranks. The old Gnutti steel cranks, which fitted to a tapered spline on the axle, were really notorious.

Race leader Ken Russell very nearly lost the Tour of Britain in 1952 when his Gnutti crank came loose on the last stage into London. Belgian rival, Marcel Michaux saw his plight and offered Russell his bike. Russell finished on the Belgian’s bike and retained his yellow jersey.

The only steel cotterless cranks that don’t seem to have had this problem are the old CCM cranks. Maybe it is because the taper on the axle was much steeper, or perhaps the machining of cranks and axles was more precise.

Of course most of the old steel cranks used cotter pins. I don’t think any of us want to go back to those. It seems very few mechanics have the necessary skill to fit cotter pins correctly these days. There were, however, some beautifully made cottered cranks. The British Chater Lea, Williams and BSA were outstanding as were the French Stronglight and Duprat. The Italian Magistroni steel cottered cranks were standard on all the top Italian bikes until Campagnolo introduced their alloy cotterless cranks in 1958. The best of all, in my opinion, were the French Duprat which had hollow steel arms. Their weight was very little more than alloy ones and they were quite elegant.

Recently I have seen steel cotterless cranks on cheap department store bikes and on high end BMX bikes. It would be interesting to know if they stand up well.

Steel chainwheels don’t seem to last any longer than alloy ones either. The thought here is that the chain beds itself into the aluminum to make a precise fit similar to the cranks and axles and very little wear occurs thereafter. This doesn't seem to happen with the steel rings. Another explanation put forward is that road grit gets bedded into the aluminum and forms a very hard surface. Does anyone else have an explanation?

Here are photos of a few cranks in my collection.

Chater Lea.

Stronglight 3 Pin cottered with Simplex rings.

Stronglight cottered 5 Pin.

Stronglight 49d alloy cotterless.

A. Duprat hollow steel cottered.


Gnutti cottered.

Williams 5 Pin.

C.C.M. cotterless, 1930.



OAP said...

Thanks for the tutorial! I remember seing online some older splined type steel bottom brackets/cranks (Gnutti?) and I wonder how those held...

And may I too propose a topic? I went to the AGO recently and saw some Greg Curnoe pieces. It'd be great, if possible, to learn more about the late artist (and cyclist).

Anonymous said...

I second that. Greg's work is sadly not very well represented on the "encylopedia" that is the internet. It would be great to pick your brain about him!

Anonymous said...

Greg Curnoe's art and his association with Mariposa will be featured in the spring edition of Dandyhorse Magazine.
I have been intending to do an article on Greg for the blog for some time. I will get at it.

Anonymous said...

Very interesting post...I really enjoy some of the old stories you bring up as well.

Thanks for sharing!


fred said...

Mike: Many thanks for your feedback. I will put any thought of a return to steel cranks and rings to rest. This actually helps optimize (albeit it is still a rough and relative value) when true classic geometry crossed with the most practical modern technology, and that appears to be the seventies! (Again, it all depends on what you are weighing, but I think most would get the gist)(Rofl...and show your age stating it!).

Now I must admit to not being privy to the very latest that's on the market, and frankly, I could care less, because it seems to me, unless you are in a race and you need to have an edge of a few seconds over 50km or so, it is pointless anyway. The performance peak, for the distance leisure cyclist, seems to have been reached (arguably) in the seventies!

That being said, I'm still taken aback over items that show in Mike's collection, like those CCM cotterless cranks from 1930:

I'm only left to believe that CCM must have produced a machine in a much higher bracket than at any time during my childhood or later.

I'm also left to wonder how many of those small circumference 5 pin mounts are directly compatible?

What a collection, Mike! Speaking of cyclists and museums...has it ever crossed your mind to actually approach the ROM or equiv to host your bike history collection?

I am biased to the seventies, and not just the music. I own a wonderful Argos Racing 531, 1974 (their first year of production), bought second hand in Taunton, Somerset for 125GBP! I had to triple the cranks and the Huret (or is it Mavic?)(Campy clones) racing set in there were just not able to be tripled, so bought the classic TAs from Bicycle Specialties, and some spare cogs for the Maillard freewheel to allow juggling the chain length to just accommodate a much wider ratio. Worked charms. The bike, other than being driven into a ditch or some other abuse, and thus the headset being peened, and thus replaced with a Stronglight roller set from Mike, is in phenomenally good shape! Huret/Mavic/Simplex components all in incredibly good shape. Ditto the paint job. British racing green.

I've decided to ship it over to Toronto this Spring. It will of course be boxed. I've always travelled with my bike on charters, and other than a bad experience at LAX with my most beloved Alcyon some years back (the idiots sent it down a chute fracturing the frame) I've had pretty good luck.

But this time, due to my refusing to renew my UK Passport (I've lost all political respect for Britannia, long story, not to mention you now have to send to Washington and pay $250+) and being a year away from citizenship and a Cdn passport, I've decided to have it shipped here. The frame size is much more optimal than my present Raleigh Gran Course 531, acquired from Mike some years back when the Alcyon was finally spent, and now, just a tad too large for me. (One only shrinks small amounts as they age, but the ergonomics of position are far more critical than thought even a few years back. It is tough on the joints for that position to not be optimal).


It worries me sick to ship this incredible find back here, even insured, and inquiries are being made the other end, and partial disassembly by my older brother is a given. (Probably forks off for safety, albeit that is a double edged sword, they have survived an impact great enough to peen the original head races without being distorted)

Has anyone had experience doing this (unchaperoned) and what would you suggest? Degree of disassembly, shipper, type of box, etc Replies most welcome, thank you.

Anonymous said...

I think Stephen needs his own blog. :^)

unbrako distributors said...

I love my old steel cranks and it I honestly do not feel the added weight that it gives my bike. But sadly my brother changed it into an alloy one without my permission, it doesn't look as sleek and cool as the old one.

cement mixer said...

I use Williams 5 Pin in my bike. I think these older cranks are better than the aluminum or fiberglass ones I see in the market today.

Anonymous said...

I love to take this on my thailand villas one day.

Sammy G said...

the arguments put forward here are simply wrong. High quality aluminium may be superior to low quality steel, but there is no way that any aluminium component will be more durable than HIGH QUALITY steel. unfortunately modern mass-production favours the relative malleability and ease of machining and shaping of aluminium. Top quality vintage steel components are vastly more durable than the best alloy components available today. the reason people had problems with the square-taper working loose or wearing in the past was due to innacurate machining of the tapers, or using BB and crank from different manufacturers with different taper dimensions. he bit about alu chainrings wearing better because of impregnated with grit is just hogwash. Just look at any bike, you see all that grey residue all over rims, brake block, and drivetrain? thats aluminium dust from alu components wearing out FAST.

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Elliott Broidy said...

Great tips!

Unknown said...

Have a 74 French St. Etienne...with Duprat...pedaled many happy miles with...very smooth action...i have 85 Peugeot 12 sp...aluminum crank...lighter but 10sp rolls more solid...hard to explain...