check your "vintage" cranks !!!

General Help
1

Highlighted in this recent blog entry is a crank failure that seemed pretty epic. “Just riding along” and pow !!!. Clearly the cranks are old campy strada “road” cranks that were anodized gold to look like Campy BMX crank arms.

Anyway, none of that matters as much as old cranks are old cranks and some of you may not be aware of their failures. Not being alarmist but just pointing out that its good to regularly check for any hairline cracks, wear from pedals straps or shoes, or scratches that could potentially result in crank failure. As most of buy and sell old used cranks I should also highlight common stress points and failure areas that perhaps some of you noobs may not be aware of. :stuck_out_tongue:

Occasionaly, even Uncle Spirito™ gets caught out: below is case of death crank from a pair of Campy cranks I’d bought from an unsuspecting seller on these forums. It all worked out OK in the end and I’m just posting so you guys know what to look for and more importantly know what to ask about.

Campy cranks were some of the worst … especially where the spider joins the crank arm, that’s a major stress point and poorly designed. But, most of the Campy cranks out there have had the obvious arm/spider issue resolved by “those in the know” with a quick file and about 1 mintues work. I’ve seen crank failures in many other brands too so it’s worth to check 'em now and again :wink:

Below is a PM (snipped) that I sent and some pics of cranks I bought. It all worked out good in the end (+ i gave it a few months so the other party wont be slighted). I’m only posting the below so others might also be made aware. If in doubt - bin it, but if you are gonna sell it on please make it known … nobody deserves faceplant karma :-o :evil:

Campy cranks can fail from cracks where the arm meets the spider on the drive side. Generally most cranks out there have been filed down just a touch because this preemptive measure usually catches the issue. Some haven’t been touched like the ones I have and the cracks have progressed to be to deep to file out. The tough part is you can’t tell when the cranks will crack but it’s been fairly well documented. Below are pics of the drive side crank showing the cracks at the webbing …

http://www.cyclebucket.com/images/crack1.jpg
http://www.cyclebucket.com/images/crack2.jpg
http://www.cyclebucket.com/images/crack3.jpg
http://www.cyclebucket.com/images/crack4.jpg
http://www.cyclebucket.com/images/crack5.jpg
http://www.cyclebucket.com/images/crack6.jpg
http://www.cyclebucket.com/images/crack7.jpg

The cracks measure between 3 to 5mm. If they were smaller I wouldn’t think twice as they would easily file out and it would take two minutes. As they are deeper I am not sure how much meat I can file out of the web to ensure the cracks are negated. Below is a few links of crank failures that result from these cracks.

http://pardo.net/bike/pic/fail-016/index.html
http://bulgier.net/pics/bike/Broken/Way_Cracked_Campy_Crank.html
http://pardo.net/bike/pic/fail-001/FAIL-008.html
http://pardo.net/bike/pic/fail-001/FAIL-035.html
http://pardo.net/bike/pic/fail-001/FAIL-052.html

The 2nd issue is that the non drive side taper has been rounded. Sometimes this happens from not being securely tightened down whilst being ridden and I can’t quite offer proof but I’ve noticed this happens more when fitted to an incorrect taper axle (non campy - jis instead of iso). It’s not sudden fail but progressively the taper gets looser and rounder as there is always a bit of play and it becomes exaggerated hence unusable.

http://www.cyclebucket.com/images/taper1.jpg
http://www.cyclebucket.com/images/taper2.jpg
http://www.cyclebucket.com/images/taper3.jpg
http://www.cyclebucket.com/images/taper4.jpg

I was disappointed when I learnt that both sides of the cranks had issues and were compromised. I also regret not asking specifically about these points as I assumed by your 4-Sale post that the item description had taken all aspects into account especially when it comes to functionality.

You probably weren’t aware of this points I’m raising. I’m guessing these came as parts on a bike you purchased and weren’t suited to your needs so was clearing them to raise some coin. I think it’s a bummer for both of us.

2

I started a similar thread a while back.

I’ve ground and polished cracks out of two pair of 151BCD Campy Pista cranks so far and am currently on my 3rd set. I’ll photograph the process and post the results.

These are my Suntour Superbe cranks, also cracked:

I have another pair of Sugino Super Mighty cranks that don’t have any cracks (yet), and used to have a pair of Dura Ace cranks that had been ground before I got them.

I’ve never personally seen a crank fail at the arm or pedal eye, but when you look at the horrible machining quality on old Campy cranks it’s hardly surprising with all the stress risers present (plus toestrap wear also)

Poor Campy design, copied by Zeus, Galli, Sugino/Suntour/Shimano…

3

I’ve never used them but it makes sense to use washers between the crank/pedal interface. A lot of crank arms get chewed there.

I’ve had one failure on a crank (spider/arm) but that’s before I knew any better and the bike shop honoured the warranty (Campy Cranks back in mid the 80’s). I think Sugino’s were “better than the rest” in terms of copying a bad design.

btw … surely one of those 151bcd left side cranks needs to be retired :wink: I’ll even pay for postage if it’s 165mm

4

To quote myself from a previous thread…

But it really is an awesome book for anyone interested in this sort of stuff.

5

No real point with pedal washers unless you use conical / chamfered ones and machine your crank to suit. Jobst has written volumes on this.

My Super Mighty’s are definitely better than Record / Dura-Ace / Superbe.

I have a complete 151 Pista crankset. 165mm, original chainring bolts, English BB. Trade you for a triple triangle Bundy?

#2 is being raced by a BCC member and #3 is going on Erle’s Kenevans.

6

there is a set of those gold ano’d cranks in the window of a bike shop on nicholson street that have snapped in half. wouldnt like to see the result of that!

7

:smiley: cheeky (but worth a shot)

I just need a left (like everyone else). I have a mate who has a 165mm pista left but it’s an early one with the raised pedal lip which means they’d still be mismatched. I’m happy for now riding with a cheapo left crank and calling it period corrupt :wink: