Drilled crank arms
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Drilled crank arms
So I've seen drillings in chain rings plenty, both for weight and aesthetics. Seen it in lots of hubs too. When I took a look around though there was only one crank I found:
I just picked up a pair of similar Sugino Mighty Competition cranks below:
I'd like to replicate the drilling down the flute of the arms, and a few holes in the flutes of the spider too. I think small holes like that just in those fluted areas should be safe. I know later models of the Sugino Mighty cranks had those spiders bored completely out, so some holes should be nothing compared to that, and as far as this design goes, I found nothing about these cranks breaking or having weakness in the arms, so I'm having trouble imaging I'd be in any trouble there. I'm only 150lbs, and although I'm strong I'm no 200lb 6'4 racer, nor am I racing the bike at all.
I'm just kind of looking for opinions. I know most people will say it's a bad idea and what's the point and bla bla bla, but I like how it looks, the detail of it, and would like somebody to either affirm that it's not significant enough to harm the integrity of the cranks, or that for sure I'd end up breaking them because here are 10 pictures of vintage fluted cranks that all broke down the arm.
Just to make sure it's clear, I wouldn't be drilling around the pedal holes at all, nor anywhere that isn't already fluted. And the holes would be small, just like in that Campy crank
I just picked up a pair of similar Sugino Mighty Competition cranks below:
I'd like to replicate the drilling down the flute of the arms, and a few holes in the flutes of the spider too. I think small holes like that just in those fluted areas should be safe. I know later models of the Sugino Mighty cranks had those spiders bored completely out, so some holes should be nothing compared to that, and as far as this design goes, I found nothing about these cranks breaking or having weakness in the arms, so I'm having trouble imaging I'd be in any trouble there. I'm only 150lbs, and although I'm strong I'm no 200lb 6'4 racer, nor am I racing the bike at all.
I'm just kind of looking for opinions. I know most people will say it's a bad idea and what's the point and bla bla bla, but I like how it looks, the detail of it, and would like somebody to either affirm that it's not significant enough to harm the integrity of the cranks, or that for sure I'd end up breaking them because here are 10 pictures of vintage fluted cranks that all broke down the arm.
Just to make sure it's clear, I wouldn't be drilling around the pedal holes at all, nor anywhere that isn't already fluted. And the holes would be small, just like in that Campy crank
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from experience in drilling holes in motorcycles - anything between the "webs" of a casting holds very little strength.
I would be happy to do it. Counter sink the holes for a smooth edge/slightly more weight shavings
I would be happy to do it. Counter sink the holes for a smooth edge/slightly more weight shavings
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Hey, why not? As long as you have the skills to do it accurately enough...
I'd use bigger holes. The diameter of the flat area of the thin sections.
I'd use bigger holes. The diameter of the flat area of the thin sections.
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Should be fine .... but making it look good can be tricky.
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There should be no major issue with drilling the arms in the web area, provided you don't go crazy. It's a balancing act, of sorts. As the holes get bigger, you remove material from the cross-section, which weakens the arm. Taken too far, the arm loses rigidity. Taken further, it breaks. However, as the holes get smaller, they cause stress concentrations which increase the liklihood of stress cracking. Aluminum is especially prone to this, so you shouldn't go any smaller than the small holes in the example you provided. The main thing is to chamfer the holes with a coutersink, and make sure there are no rough edges inside the holes. Ideally, you should drill them slightly undersize and ream them to get a smooth surface finish. If you could polish the holes, that would be even better. Good luck. Post pics when you're done.
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Holes in the web area of the crank arms should be safe enough but I'd be VERY leery of drilling holes around the pedal eye if for no other reason than the drilled crank you show seems to have a lot more metal around the pedal eye than the Suguino crank you propose to modify.
Interesting to see the return of "Drillium".
Interesting to see the return of "Drillium".
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Back in the Middle 80s a light weight craze swept cyclist. They were drilling out everthing!!! Then parts began to fail. They came to the amazing conclusion that for the price of a few grams they were rewarded with a broken bike.
Really people eat a couple less cookies and take pound off. It is all the same, and the bike will finish the ride or race.
Really people eat a couple less cookies and take pound off. It is all the same, and the bike will finish the ride or race.
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Zeus 2000 had drillium arms and rings from the factory:
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It's interesting to note that on several web sites they describe the old Campagnolo Super Record and Victory brake levers as being drilled for weight. The levers were not drilled but manufactured that way, so in reality both levers weighed more than the available none drilled levers (Record and Triomphe); the Campagnolo reason was to keep ones hands dry so they wouldn't slip on the smooth levers.
Last edited by onespeedbiker; 08-29-12 at 11:21 PM.
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I'll mock up some versions in photoshop to see what I think looks best first, how many holes, what size, where exactly.
There should be no major issue with drilling the arms in the web area, provided you don't go crazy. It's a balancing act, of sorts. As the holes get bigger, you remove material from the cross-section, which weakens the arm. Taken too far, the arm loses rigidity. Taken further, it breaks. However, as the holes get smaller, they cause stress concentrations which increase the likelihood of stress cracking. Aluminum is especially prone to this, so you shouldn't go any smaller than the small holes in the example you provided. The main thing is to chamfer the holes with a coutersink, and make sure there are no rough edges inside the holes. Ideally, you should drill them slightly undersize and ream them to get a smooth surface finish. If you could polish the holes, that would be even better. Good luck. Post pics when you're done.
Back in the Middle 80s a light weight craze swept cyclist. They were drilling out everthing!!! Then parts began to fail. They came to the amazing conclusion that for the price of a few grams they were rewarded with a broken bike.
Really people eat a couple less cookies and take pound off. It is all the same, and the bike will finish the ride or race.
Really people eat a couple less cookies and take pound off. It is all the same, and the bike will finish the ride or race.
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Sorry about missing your disclaimer that you weren't thinking about drilling the pedal eye area. As to the engraving, during the "drillium" era there was also a fad of "pantographing" components, i.e. engraving designs, logos, the maker's name, etc. and filling the engraved lines with contrasting colored paint. It made for a striking appearance but also led to a lot of broken parts (can you say "stress raiser"?) and quickly went out of fashion.
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Sorry about missing your disclaimer that you weren't thinking about drilling the pedal eye area. As to the engraving, during the "drillium" era there was also a fad of "pantographing" components, i.e. engraving designs, logos, the maker's name, etc. and filling the engraved lines with contrasting colored paint. It made for a striking appearance but also led to a lot of broken parts (can you say "stress raiser"?) and quickly went out of fashion.
And I didn't know it was ever a fad and caused issues. Perhaps then I won't be engraving and drilling the same crankset lol. Maybe another project for another time.
It's funny the longer I ride bikes the more I realise sometimes you end up with more than one bike that serves the same purpose, you just have so many components you really like how can you choose between them all.
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Links on this page to drillium articles from the era:
https://www.tearsforgears.com/2005/09/drillium-info.html
Fun to read.
The engraving is beautiful. But I can think of no better way to initiate a fatigue crack in aluminum. If you have your cranks engraved, hang them on the wall. Don't ride them.
https://www.tearsforgears.com/2005/09/drillium-info.html
Fun to read.
The engraving is beautiful. But I can think of no better way to initiate a fatigue crack in aluminum. If you have your cranks engraved, hang them on the wall. Don't ride them.
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How about the drilled crank arms like the Rotor system?
https://www.rotorbikeusa.com/3d_road_cranks.html
https://www.rotorbikeusa.com/3d_road_cranks.html
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Most crank arms come with 2 big holes in them from the factory,they don't seem to crack real often.....go for it.
Make sure to break the edge on everything.Just don't go crazy,it'll be fine.
I like the way it looks,if I was more OCD,I'd do it to everything I own.
Make sure to break the edge on everything.Just don't go crazy,it'll be fine.
I like the way it looks,if I was more OCD,I'd do it to everything I own.
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...As the holes get bigger, you remove material from the cross-section, which weakens the arm. Taken too far, the arm loses rigidity. Taken further, it breaks. However, as the holes get smaller, they cause stress concentrations which increase the liklihood of stress cracking. Aluminum is especially prone to this...
Please OP, read the above twice.
I'm a mechanical engineer, and from what I know about metals and stress distruibution, I will tell you that without actually testing your modifications, you'll likely see a very serious decline in the part's structural integrity which might give no clue to when a catastrophic failure will occur. Ask yourself, "how much do I know about the grain structure's orientation in this forging".
The bigger holes induce the very flex which can cause rapid failure, and the small holes create the highest stress concentrations.
Pick your poison!
This drillium activity should really be only for display parts, not riding.
This reminds me of the guys in the cities who ride their bikes with no brakes, and so I must question the definition of "cool".
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Holes in frames and bike parts is real dangerous: Don't do it.....Mom always said I would kill myself......
Delta Sports Frame......looks like an accident waiting to happen......they're so bad their only making 200 of them.....
Like everything in life,there's a risk,whether you drill it or not.How many people you know or have heard about being injured from drilling their bike parts?
If you weight 300-400 pounds,are a body builder,use your bike to jump off of cliffs,race down the side of volcanos....you might not want to drill your parts.
If your like me and tour on your bike,ride around the city and go to the beach....drill away,just don't go crazy.If you can't sleep at night,don't drill it all the way through,it will still look nice.
Delta Sports Frame......looks like an accident waiting to happen......they're so bad their only making 200 of them.....
Like everything in life,there's a risk,whether you drill it or not.How many people you know or have heard about being injured from drilling their bike parts?
If you weight 300-400 pounds,are a body builder,use your bike to jump off of cliffs,race down the side of volcanos....you might not want to drill your parts.
If your like me and tour on your bike,ride around the city and go to the beach....drill away,just don't go crazy.If you can't sleep at night,don't drill it all the way through,it will still look nice.
Last edited by Booger1; 08-29-12 at 12:51 PM.
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Parts like the frame above are tested before going into production.
Yours is a lousy point. But, since it's not your bike being drilled, I guess it doesn't matter?
The point I made, that you refer to, is that without testing of the drilled parts, they are upteen times more-likely to fail.
Another point to consider is that none of us will live forever. Death could come at any time!
So, if your posessions/estate were sold off, do you really want some un-knowledgeable new owner having to pay the consequences of your hapless re-engineering of a crankarm or handlebar clamp?
These modifcations are like sabotage imo.
Yours is a lousy point. But, since it's not your bike being drilled, I guess it doesn't matter?
The point I made, that you refer to, is that without testing of the drilled parts, they are upteen times more-likely to fail.
Another point to consider is that none of us will live forever. Death could come at any time!
So, if your posessions/estate were sold off, do you really want some un-knowledgeable new owner having to pay the consequences of your hapless re-engineering of a crankarm or handlebar clamp?
These modifcations are like sabotage imo.
Last edited by dddd; 08-29-12 at 01:42 PM.
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I'm pretty sure the crank shown in the original post is not actually drilled through. I think Jeff has just done small stopped holes and filled them with paint. At least that's what looks like in that photo. He's forum member "drillium dude" so you can ask him if you want.
Italvega used Record cranks with large holes drilled down the center of the cranks on their Superlight model, as well as many drilled components. I always thought the holes down the center of the crank were a really bad idea and did not look really look good either. But the work on the rest of the bike was very cool.
Italvega used Record cranks with large holes drilled down the center of the cranks on their Superlight model, as well as many drilled components. I always thought the holes down the center of the crank were a really bad idea and did not look really look good either. But the work on the rest of the bike was very cool.
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The Italvega Superlight probably had the most OEM drillium https://s183.photobucket.com/albums/x...%20Superlight/ unless you count Affinity Cycles Drillium https://prollyisnotprobably.com/2010/...-drillium-212/
Last edited by onespeedbiker; 08-29-12 at 11:46 PM.
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It's interesting to note that on several web sites they describe the old Campagnolo Super Record and Victory brake levers as being drilled for weight. The levers were not drilled but manufactured that way, so in reality both levers weighed more than the available none drilled levers (Record and Triomphe); the Campagnolo reason was to keep ones hands dry so they wouldn't slip on the smooth levers.