question about a campy crank

[GOTHBROOKS]

this crank doesnt have those inner tabs for two chainrings. its 144bcd. but its marked as strada and not pista. is it a bmx crank?

[RobJ]

No it's a Campy road crank very similar to the Pista. Same BCD and provisions for single ring. There is a slight difference though in the chainring ledges. Some say you have to file them down slightly. Or run the ring on the outside. Usually requires experimenting with the BB spindle to get enough clearance.

[spinarelli]

Yes, bmx chainset, circle zero makes it 1980.

[RobJ]

Interesting, just found them here...

http://velobase.com/ViewComponent.aspx?ID=48b9b3f8-a298-459d-a860-f955112068a7&Enum=115

[GOTHBROOKS]

cool i was thinking either bmx or something for a tandem.

[spinarelli]

It could be tandem if it has reverse thread for the pedal to go on the non drive side.

[spinarelli]

Interesting, just found them here...

http://velobase.com/ViewComponent.aspx?ID=48b9b3f8-a298-459d-a860-f955112068a7&Enum=115

Hm, Velobase only lists 170 but the vintage catalog says 175 too. Also that’s available in gold and blue.

[ultraman6970]

If the threads in the pedal arent backwards, then to me looks more like a bmx crankset. If the pedal threads are backwards then belongs to a tandem setup as somebody mentioned.

[GOTHBROOKS]

a pedal just threaded in normally so they arent backwards.

[spinarelli]

a pedal just threaded in normally so they arent backwards.

Congratulations, you got a bmx crank. Now hunt down the rest of the bmx groupset.

Hubs here:http://campyonlyguy.blogspot.ca/2013/12/todays-retro-shots-campy-bmx-hubs.html

[GOTHBROOKS]

i heard stories about guys in the late 80s using these cranks on track bikes and legit breaking them in half while sprinting and doing bike throws. i dont know if theres any actual validity to that old wives tale but im still gonna put them on my track bike.

[ultraman6970]

Personally Ive seen more that era campy cranksets cracked and broken (road and track) than shimano ones.

[Hindmost]

I broke two of them bitd and that is not a testament of any particular personal strength. Often enough they would snap off at the pedal end. One story had it that the threads were cut improperly so that the mounted pedal forced stresses into the end of the crank. Jobst Brandt had his own theory and engineered a solution.

[bfd]

I broke two of them bitd and that is not a testament of any particular personal strength. Often enough they would snap off at the pedal end. One story had it that the threads were cut improperly so that the mounted pedal forced stresses into the end of the crank. Jobst Brandt had his own theory and engineered a solution.

Jobst Brandt's broken pedal eye solution

http://pardo.net/bike/pic/fail-001/CrankmodXside2.jpg

[Mark McM]

There are a lot of broken Campagnolo cranks from that era. But contrary to popular conception, they didn't snap from a single momentary overload (i.e., the rider didn't rip them apart from their great leg strength). The design and construction of these cranks created a few spots with high stress concentrations. Over time (and many load cycles), cracks started at these high stress points. These cracks continue to grow, until they reached a point where the that one final hard stress caused them to break (i.e., that last load was the "straw that broke the camels back"). If these cranks had been examined immediately prior to when the broke, no doubt the cranks would have been detectable. Even after the fact, an examination of the broken cranks will show the signs of the initiation and growth of the cracks over time.

There's photos of a number of these broken cranks at: http://www.pardo.net/bike/pic/fail-001/FAIL-001.html . The photo below is a classic case, where you can see the beach marks (signs of rubbing between surfaces) around where the crack started, and you can also see rings that indicate different stages of the crack propogation. The crank in this crank was growing for some time before it finally "snapped."

http://www.pardo.net/bike/pic/fail-001/crank-fail-015.jpg

[bicycletricycle]

I assume a construction flaw would be the problem with that crank? no stress risers in that area right?

There are a lot of broken Campagnolo cranks from that era. But contrary to popular conception, they didn't snap from a single momentary overload (i.e., the rider didn't rip them apart from their great leg strength). The design and construction of these cranks created a few spots with high stress concentrations. Over time (and many load cycles), cracks started at these high stress points. These cracks continue to grow, until they reached a point where the that one final hard stress caused them to break (i.e., that last load was the "straw that broke the camels back"). If these cranks had been examined immediately prior to when the broke, no doubt the cranks would have been detectable. Even after the fact, an examination of the broken cranks will show the signs of the initiation and growth of the cracks over time.

There's photos of a number of these broken cranks at: http://www.pardo.net/bike/pic/fail-001/FAIL-001.html . The photo below is a classic case, where you can see the beach marks (signs of rubbing between surfaces) around where the crack started, and you can also see rings that indicate different stages of the crack propogation. The crank in this crank was growing for some time before it finally "snapped."

http://www.pardo.net/bike/pic/fail-001/crank-fail-015.jpg

[Mark McM]

I assume a construction flaw would be the problem with that crank? no stress risers in that area right?

Perhaps. Or maybe a groove that was worn into the crank from rubbing on shoe buckle or pedal strap.

[oldpotatoe]

Personally Ive seen more that era campy cranksets cracked and broken (road and track) than shimano ones.

How many 70s/early 80s shimano cranks have you seen and how many were 'out there'?

[bicycletricycle]

Perhaps. Or maybe a groove that was worn into the crank from rubbing on shoe buckle or pedal strap.

good call. I have also seen front derailleur cables cut grooves in the back of cranks over time.

[GOTHBROOKS]

https://c1.staticflickr.com/1/896/26252912267_d19ce17625_b.jpg
these seem to be in pretty good shape!

[ultraman6970]

Dont take me wrong... I love the campy stuff but ive seen at least 15... suden death ones, other ones cracked... pedal, or mid like in the picture... is not that many, I do get what you are saying, they made zillions but shimano 600 ones or even the old 600 probably 1...

I do get what you say the stuff is good... saavedra from argentina made campy copy ones, they used an x-ray machine to check out their cranks before boxing them, stores were getting those bad oens with internal flaws (bubbles) to put in the windows...



How many 70s/early 80s shimano cranks have you seen and how many were 'out there'?

[oldpotatoe]

Dont take me wrong... I love the campy stuff but ive seen at least 15... suden death ones, other ones cracked... pedal, or mid like in the picture... is not that many, I do get what you are saying, they made zillions but shimano 600 ones or even the old 600 probably 1...

I do get what you say the stuff is good... saavedra from argentina made campy copy ones, they used an x-ray machine to check out their cranks before boxing them, stores were getting those bad oens with internal flaws (bubbles) to put in the windows...

Not saying Campagnolo 144mm BCD cranks didn't break, they did with frequency but late 70s and early 80s, not a whole bunch of shimano stuff around..more suntour than shimano IME, wandering around the bike shops of that era. The 'arabesque' era, 144mm BCD..

[ultraman6970]

Potato do you remember back in the day when campagnolo was taking a truck to the World cups to handle warranty problems? :) The good old days! :P

[Hindmost]

The two times I broke my cranks I rode one-legged directly to the LBS where they replaced the crank arms and I rode home. Some things I miss about BITD.