jerrymcdougal

So lets say someone has a old 144bcd Campy Record Strada Crank, and this person wants to run only one ring on the outside position. Would it be unsafe/blasphemous to have a skilled craftsman file/polish off the tabs on the inside of the spider arms where the inner ring would rest, for chainstay clearance? In other words, modify a Strada Record crank to look like the spider arms of a Record Pista crank. Said crank has already had the common/usual hairline stress cracks filed/polished out where the arm meets the spider.

What say you?

Thanks in advance.

tellyho

Definitely blasphemous. No idea as to the safety. And really, who's going to look on that side of your crankset anyway?

HillRider

Go for it. The crank is already compromised so no one with any sense would use it for any other purpose. This, after all, is just a crank, not a Rembrandt.

carpediemracing 

I'd do it.

jerrymcdougal

Compromised? If you are refering to the cracks at the spider/arm junction, Ive been told by at least a few veteran collectors that nearly every record crank they have used has developed those in no time and that they are nothing to worry about as long as you file/polish the ransitions round or flat. They are very very small. Maybe 1-2mm long.

Oh, the reason I am contemplating doing this for the guy is for usability issues not aesthetics (the tabs interfere with the chainstay on this particular frame when running a 42mm chainline). If it were a question of aesthetics I wouldnt even contemplate it.

Thanks Guys

DannoXYZ 

Personally, I think a crank looks way better with that little ledge ground off when used in single-chainring configuration.

sfclearwater

If clearance is that tight and you know you aren't going to want to use it with two chainrings again, then why wouldn't you do it?

Would be pretty easy too. I have cut/modified several cranks (like the one attached) and found a bench grinder takes care of the job quickly. An abrasive wheel leaves what is actually a pretty nice finish, but if you wanted it to be nicer you could sand the area down with increasing grit wet/dry paper; by the time you get to 1500 it should be shining.

melville

Heck, that's what Campy themselves did when they made BMX cranks in the 80s. Go all the way and counterbore the bolt holes from the back so you can run proper track chainring bolts/nuts.

Ex Pres 

If you don't counterbore the holes then the chainring bolts may still rub.

jerrymcdougal

Honestly so do I. But I probably wouldnt grind them if I didnt need to. probably.

I bet the bench grinder works well. Being a amateur framebuilder and alloy polsher, I prefer good ol files, emery cloth and then dry/wet sandpaper (800-2000 grit). If it were a beefy 80's japanese crank I wouldn't think twice about the tab mod, but Record is generally made as light as possible with the least amount of material possible. Kind of like tubesets. I wouldn't be scared to do some light filing on a gaspipe tubeset, but I wouldn't bring a file anywhere near crazy thin tubesets like OX Platinum. A nick can mean failure. I know Pista cranks are tabless stock, but never having first hand experience with a pista version, I don't well enough know if the spider arms are built the same as the strada version to be a good comparison.

Great idea, I'll have to pull out the drill press.

Jeff Wills

Nope. Campy BMX cranks were from the late '70's. I have a set that I ended up taking the anodizing off, polishing and using them (with two chainrings) on this bike:
https://home.comcast.net/~jeff_wills/...s/photo_3.html
Blasphemous? Heck, you're nowhere near me!

jerrymcdougal

Nice, well that's good enough for me. Off with them!

Thanks!

goldcoastjon

I'd say it's blasphemy, simply because you might change your mind later and want two chain rings up front. (Maybe when you're old like me and your knees aren't as strong as they were "back in the day.)

Here's another option:

Install your single front chainring in the INSIDE position, then get a Campi cyclocross chain guard for the outer position. You've kept a classy-looking Campi crank intact and kept your pants less greasy, all in one. (I did this on my Peugeot UO-18 mixte around-town bike, which once belonged to my mother. It's a terrific urban cruiser in flat Alameda with just 6 cogs in the back.)

Best,

Jon

jerrymcdougal

Not a bad idea, but I would imagine even if we did need to go back to two rings, it would work just fine, with a little more work getting the inner ring centered properly. Sound feasible?

I would take your advice about the chain guard, and I actually have a identical crank with dual cx guards (one on each side of the ring. its kinda chewed up though) but we want to go minimalistic on this build. Putting the ring on the inside just wouldn't look as clean sadly. That would make things much easier though.

Thanks Jon

DannoXYZ 

Yeah, it would be fine to use with double-chainrings later. The centering won't be an issue if you have tight clearances between the chainring-hole and chainring-bolts. There's the issue of loading the bolts in shear since there no ledge to take the radial-loads from the chainring. But if the bolts are tight, the friction will hold the chainring tight and transmit all the load to the arms without stressing the bolts in shear (actually the nut since it's on the outside).