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Drilling a steel classic road frame like swiss cheese...still safe to ride?

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Drilling a steel classic road frame like swiss cheese...still safe to ride?

Old 08-23-17, 05:25 PM
  #76  
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Originally Posted by exwhyzed View Post
- I will now resort to plan B which is to cut off the section of the drop bars that i don't use, since I only ride the hoods. I like when my fingers touch a bit of the drops so I'll probably cut around here...
I like this guy.

I am dying to hear plan C.
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Old 08-23-17, 05:29 PM
  #77  
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That drilled frame would be vertically compliant and laterally compliant, for one time only.
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Old 08-23-17, 05:43 PM
  #78  
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Of course, you don't need an extremely heavy downtube.

Slingshot Bicycle:

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Old 08-23-17, 07:11 PM
  #79  
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Originally Posted by SquidPuppet View Post
That is a huge assumption. And 99.9% likely to be wrong. Once someone makes the decision to start drilling holes the size of half the tubing diameter in a bicycle frame, they've already gone too far.
I agree with SquidPuppet. (A phrase that, until I joined BF, I would have predicted that I would never write).
Read "To Engineer is Human: The Role of Failure in Successful Design" by Henry Petroski, a Duke engineering professor. We engineers design something that we THINK will work. It breaks, and we figure how to fix that design. Then we get confident, and overconfident, and extend the design to the point where it breaks again. Petroski uses bridge design as an example in his book. We take a good design for a 500 foot bridge, extend it to 1000 feet, the main failure modes change, and it fails. Keep in mind that we engineers start with training that allows us to accurately calculate strengths, failure modes, etc. Intuition isn't very good for precise quantitative estimates in complex systems. But our initial designs almost always break. If not, they're overdesigned and too 1) expensive, 2) heavy, 3) non-functional. Whether failed or overdesigned, the initial design always needs tweaking.

For someone without that experience (in this case, without the extensive experience of learning what happens when you drill at point "A". And "B". And "C"), your design will almost certainly fail.
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Old 08-23-17, 07:13 PM
  #80  
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in a strange coincidence, someone posted a pic of a frame with a batch of holes in it in the facebook framebuilder's group on the same day as this thread was started. I assume it wasn't the same person

True temper published rider weights for their tubesets, I don't think anyone else does. TT's weights were pretty low, some <200 lb
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Old 08-23-17, 07:42 PM
  #81  
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Hey, just for fun... I did some math - with some assumptions.
0.283 pounds per cubic inch for the density of steel. Plus or minus depending on the type used.
I assumed a wall thickness of 0.049" - which might be thinner than a cheap bike. But it's what I picked.
I assumed 10 holes in the top tube, 10 holes in the seat tube, and 15 holes in the down tube.
I assumed the tubes were 1" in diameter, and the holes were 0.5" in diameter.
I assumed the holes are 2-D. It's late, didn't want to calculate the actual material removed. It's just an estimate.

So....
Area * wall thickness * number of holes * Density = weight savings.
(Pi*0.25"*0.25") * (0.049") * (35) * (0.283 pounds per cubic inch) = 0.095 lbs

I think I did that right... (feel free to check me... it's late here.)

Hey, lets bump up those numbers to something ridiculous.
0.0625" wall thickness
1" dia holes into a bigger tube
You could save 0.49 lbs.

Be fun to look at the stiffness, elongation, yield strength, etc... I'm sure this would fail hard for the OP, with almost no gain.
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Old 08-23-17, 08:04 PM
  #82  
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Originally Posted by CliffordK View Post
If you have a basic high tensile steel frame... why not... you can't really reduce its value any more.

HEY!!! I'm offended by that comment.




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Old 08-23-17, 09:48 PM
  #83  
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Originally Posted by CliffordK View Post
With a straight tube chromoly frame, then you likely have a fair amount of excess material mid tube that could potentially be removed. Sanding, lathe, or... DRILLING.
Again a fundamental lack of understanding makes things seems clear.

I tuber has better strength that its weight and wall thickness would suggest because it uniformly transmits stresses. And a stress point and you weaken the tube fart beyond what the amount of material removed would suggest.

As has neen suggested above, Axially drilling that tube, or somehow precisely grinding the inner walls thinner, might safely and very very minimally reduce weight.

Might I point out that this guy weighs 220 lbs and is looking to remove as much as several grams from his bike to "improve performance."

What is Not wrong with this picture?
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Old 08-23-17, 11:06 PM
  #84  
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Originally Posted by Maelochs View Post
Again a fundamental lack of understanding makes things seems clear.

I tuber has better strength that its weight and wall thickness would suggest because it uniformly transmits stresses. And a stress point and you weaken the tube fart beyond what the amount of material removed would suggest.

As has neen suggested above, Axially drilling that tube, or somehow precisely grinding the inner walls thinner, might safely and very very minimally reduce weight.

Might I point out that this guy weighs 220 lbs and is looking to remove as much as several grams from his bike to "improve performance."

What is Not wrong with this picture?
I never said it would work. I just want to watch him try it cause I think it'll look cool. Provided he doesn't ruin a perfectly good SL or SLX or 753 etc frame.
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Old 08-23-17, 11:19 PM
  #85  
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Originally Posted by corrado33 View Post
Provided he doesn't ruin a perfectly good SL or SLX or 753 etc frame.
Could one shave a little weight from a vintage Schwinn Varsity?
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Old 08-24-17, 12:05 AM
  #86  
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Originally Posted by Kapusta View Post
I like this guy.

I am dying to hear plan C.
Fabricate a new light handlebar like on this bicycle.


Last edited by Barabaika; 08-24-17 at 12:21 AM.
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Old 08-24-17, 06:56 AM
  #87  
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Originally Posted by CliffordK View Post
Could one shave a little weight from a vintage Schwinn Varsity?
I have long suspected that those little tubes on a varsity are actually solid bars. My back still twinges when I think about lifting one
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Old 08-24-17, 07:02 AM
  #88  
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OP should ride a unicycle, then he won't have all those extra pesky parts to worry about.
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Old 08-24-17, 07:11 AM
  #89  
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Originally Posted by maelochs View Post
might i point out that this guy weighs 220 lbs and is looking to remove as much as several grams from his bike to "improve performance."

what is not wrong with this picture?
+1
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Old 08-24-17, 07:23 AM
  #90  
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Originally Posted by exwhyzed View Post
- strategically drilling holes such that safety isn't impacted wouldn't reduce the weight enough for me to make a "poor man's" light bike
How light are you realistically trying to get to? Why not just look for any number of lightweight vintage bikes coming in the low 20# range, which often don't command too much of a premium over their hi-ten counterparts? For example, there are a couple Centurion Ironmans sitting on my local CL right now, with 105 components and new weights in the 22# range, for $200ish. They are going to be much better riding bikes than a "poor mans light bike" consisting of a drilled out hi-ten frame with cheap parts, and far less likely to toss you into the path of a passing car when your frame buckles in half.

Past that, there are no "poor mans" lightweight steel bikes unless you find a screaming deal on CL. There are "poor mans" nice riding steel bikes, there are "rich mans" lightweight steel bike. If it was plausible to make lightweight steel bike cheap by drilling out the frame, manufacturers would have done it long ago.

In any case, if you want to chop the handlebars, go for it. No real risk there.
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Old 08-24-17, 08:47 AM
  #91  
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Originally Posted by Maelochs View Post
As has neen suggested above, Axially drilling that tube, or somehow precisely grinding the inner walls thinner, might safely and very very minimally reduce weight.
It would be easier to grind the outer walls thinner, no?
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Old 08-24-17, 08:49 AM
  #92  
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Originally Posted by exwhyzed View Post
...I like when my fingers touch a bit of the drops so I'll probably cut around here...
Well.. now I'm wondering how much that pesky pinky weighs.
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Old 08-24-17, 09:44 AM
  #93  
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I remember the weight weenies of the 80s. They drilled out virtually everything they could on bikes to get rid of milligrams of weight. Everything broke.
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Old 08-24-17, 09:50 AM
  #94  
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For Eddy Merckx Hour attempt at the Mexico city Velodrome . Ugo DeRosa built him a very light Track Frame,
it did have some strategic applications of drillium .. but it did not have to be used for long, but it did have to survive a
sustained power output from one of the greatest racing cyclists ..
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Old 08-24-17, 10:18 AM
  #95  
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Okay guys, I'm going to eat some crow......

You are right, I missed the OP said he's considering holes half the diameter of the tube.... I do miss a lot of details because I skim too fast and ignore a lot of posts that don't catch my eye. Plus.... I forget a lot too. Hopefully not alzheimer's. It's been a worry since I hit fifty y.o. nine years ago.

I'm also going to state that I don't think it is a good idea for the OP to do this with the intent for this to be his main bike for commutes or other riding. Maybe every now and then after the modded bike has shown one way or the other it's capability.

Some additional two cents. My current bike, a 78 Raleigh Competition G.S. weighs 24 lbs with bottle cages and bag under the seat. I estimate the frame at most is only six pounds. That leaves 18 pounds of wheels, tires, handle bars, seat plus post, crank, chain wheels, rear sprockets, brakes, brake levers etc.....

Even if I removed half the material, I'm only saving three pounds. An I don't think I could possibly remove half the material without getting into the brazing or welds at the joints.

Additionally, the tubing that the truly lightweight steel bikes, I'm talking less than 25 or so pounds, tends to be a higher tensile steel which might imply it is less ductile and might develop a crack without showing signs of deformation. Cracks can go unnoticed or can develop rapidly. Either way they will cause bad things to happen very quickly before the rider notices.

The heavier bikes will be made of steel that generally has lower tensile strength and is more ductile. If the bike survives the first sitting and few bumps in the road, will only deform and bend at a rate that the rider will be able to notice and stop before a big accident occurs.

Chrome-molly tube used in many low priced steel frame bikes (it's been used in some high priced too.. but lets not go there please..) I'll start over Chome-molly tube is fairly ductile. Strong stuff but it will likely bend before cracking. I think my Varsity was chrome-molly tube. The hole bike was 44 pounds and similar components to my Raleigh with the exception of steel wheels and steel handle bars.

So if we say that 23 pounds of it were the components, then the frame was around 21 pounds. Again, even if half the material is removed from the frame. that is only 10.5 pounds from the 44 initial pounds which puts us at a bike weighing 33.5 pounds. Well over the weight of a truly lightweight vintage 22 pound steel bikes that I've seen go for less than 150 dollars on ebay, which is generally full of way overpriced listings.

Again I wouldn't drill the truly lightweight steel bikes. If there was a benefit, they would have done that.

If the OP wants a light bike to commute and regularly ride on the paved roads and trails. I recommend an old steel road bike such as a scwhinn tempo, premis, or circuit. They are roughly 22 pound bikes as originally equipped. The first two, tempo and premis, do occasionally go for less than 150 dollars. I did see a circuit that went for 35, but that was an anomaly as they were among the lightest schwinns. They don't have the value of a Paramount, but they generally will be 200 to 400 when reasonably priced.

I grew up around metal workers, welders, machinists and such. My main education and career was elsewhere (pilot) but before going into semi-retirement, I spent my last ten years helping a friend who is an engineer in his machine shop. I've worked with steel tube. Holes are not a bad thing. The top, down and seat tube will mainly have compression and tension forces. The drilled tube will likely survive that. But as I said earlier, pedaling imparts torsion and bending force to the tube. Those forces need to be minimized.

I'd be more leary of drilling the fork, back stays and chain stays.

I hope the OP will try it just for the novelty. Something to take to certain rides and events that he finds it capable of. Albeit he shouldn't ride hard. Hard pedaling puts a lot of stress on a frame. But let us know how it goes... get plenty of pics.
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Old 08-24-17, 10:19 AM
  #96  
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Oh, I'm going riding. it will be three or four hours till I get back for my chastising.
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Old 08-24-17, 10:22 AM
  #97  
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Originally Posted by jefnvk View Post
How light are you realistically trying to get to? Why not just look for any number of lightweight vintage bikes coming in the low 20# range, which often don't command too much of a premium over their hi-ten counterparts? For example, there are a couple Centurion Ironmans sitting on my local CL right now, with 105 components and new weights in the 22# range, for $200ish. They are going to be much better riding bikes than a "poor mans light bike" consisting of a drilled out hi-ten frame with cheap parts, and far less likely to toss you into the path of a passing car when your frame buckles in half.

Past that, there are no "poor mans" lightweight steel bikes unless you find a screaming deal on CL. There are "poor mans" nice riding steel bikes, there are "rich mans" lightweight steel bike. If it was plausible to make lightweight steel bike cheap by drilling out the frame, manufacturers would have done it long ago.

In any case, if you want to chop the handlebars, go for it. No real risk there.
Can you list a few more or direct me to where i can find out the names of more vintage light steel frames?

Last edited by exwhyzed; 08-24-17 at 12:04 PM.
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Old 08-24-17, 10:26 AM
  #98  
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Originally Posted by Iride01 View Post
My current bike, a 78 Raleigh Competition G.S. weighs 24 lbs with bottle cages and bag under the seat. I estimate the frame at most is only six pounds. That leaves 18 pounds of wheels, tires, handle bars, seat plus post, crank, chain wheels, rear sprockets, brakes, brake levers etc.....

Even if I removed half the material, I'm only saving three pounds. An I don't think I could possibly remove half the material without getting into the brazing or welds at the joints.
Drill the rims between spokes? Toss the seat and post and ride standing ... He's already planning to cut off half the bars. Drop the brakes ... Fred Flintstone didn't need no stinkin' dual-pivots.Go to single-speed .... or just push it up hills and coast down. Oh, and drill the tires.

And of course, cut away half the frame.

Oh, and get some lightweight bar tape. That's ll help.
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Old 08-24-17, 10:37 AM
  #99  
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Originally Posted by Kapusta View Post
I like this guy.

I am dying to hear plan C.
Plan D must be to remove every other spoke in each wheel.
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Old 08-24-17, 10:49 AM
  #100  
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Originally Posted by Maelochs View Post
Drill the rims between spokes? Toss the seat and post and ride standing ... He's already planning to cut off half the bars. Drop the brakes ... Fred Flintstone didn't need no stinkin' dual-pivots.Go to single-speed .... or just push it up hills and coast down. Oh, and drill the tires.

And of course, cut away half the frame.

Oh, and get some lightweight bar tape. That's ll help.
Or, you know, go on a diet and lose about 40 pounds and you'll be surprised how easy it is to push an undrilled, unchopped bike up a hill. I know it's gotten a lot easier for me since I dropped 50 pounds.
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