Mountain Bike Reviews Forum banner
1 - 20 of 22 Posts

·
Registered
Joined
·
37 Posts
Discussion Starter · #1 ·
Classic weight weenie idea?

I am trying to lighten up my XC bike. Would drilling out larger holes in the cassette and chain do anything? How big could these holes be without doing structural damage? Where would be the best place to place the holes?

As for pessimists who say you can not accurately put holes in metal, give me a break. I'm a dental student and plan to use a dental drill with some burs to make the holes. The smallest bur I have can make a hole 0.3mm in diameter. I have the skills and the tools to precisely drill the parts. Now I just need some help figuring out where to put the holes and how many are allowed.
 

·
Registered
Joined
·
2,431 Posts
After one guy saw Eddy Merckx's drilled out chainrings on some of his hour record bikes he attempted it himself. Looked fantastic....he rode and three pedal strokes down the road the chainring folded - he'd saved 10g.
 

·
Registered
Joined
·
37 Posts
Discussion Starter · #4 ·
I do see how thinning could reduce much more material than punching holes. What about enlarging the holes in the cassette that shimano put from the factory? Say if the holes are 1mm in diameter, boring them out a bit more, say to about 1.5-2mm?

As for the thinning idea, would it be best to thin the arms that go out to the cog on the individual gear or some other part?
 

·
ups and downs
Joined
·
15,599 Posts
Cassette cogs are right on the margin of folding over as it is (see numerous Drivetrain threads about bent Shimano and broken SRAM cassette cogs). You're better off chasing other components for weight shaving if you want to maintain reliability. Or look at the Recon Ti cassettes.
 

·
Registered
Joined
·
37 Posts
Discussion Starter · #8 ·
The cassette I have now is around 400 to 500g, I did not weigh it, but looking on weightweenies.com, it puts it into that range. The one I'm replacing it with is either 305g or 330g. I was planning to reduce the weight down to around 200-250g, but after discussing it, I realize that means taking off up to 1/3rd of the material...

I think the best bet would be to go with lightweight and leave it be.

Thanks for the advice
 

·
WTF
Joined
·
292 Posts
If it were meant to have holes or be thinner or have less material, It already would be that way from the factory.

the only thing I would ever drill holes in is maybe the....well..come to think of it, nothing....I would never drill into any expensive mtb parts.
 

·
Registered
Joined
·
125 Posts
what about cheap parts? like cheap steel cassettes?

The reason it is not that way from the factory is to decrease end cost to the consumer, and to cover their ass by making it more durable than it needs to be. Another reason is the process of manufacturing and tooling. For example if their was some weight to be removed from a part it is likely not possible without adding an additonal process. Not everyone wants to pay for that.
 

·
Registered
Joined
·
150 Posts
If you do the calculations, you'll find that making small holes removes negligible weight. Similarly, making small holes a bit bigger will make negligible difference.

Making big holes does some good, but finding room for big holes is difficult.

I've drilled into the flats on bolts, without piercing the threads, that made a few g difference, drilled some washers, small holes therefore not much difference. Both looked good in my view. Generally removing metal with saw and grinder makes much more difference, e.g. shortening gear levers, hacking away at the sides of seatpost spacers, cutting slots into brackets.

I've done about as much as its possible to do without affecting safety, and saved 89g over the whole bike, but it took about 35 hours. Luckily I enjoyed doing it ;)
 

·
Registered
Joined
·
1,592 Posts
what about cheap parts? like cheap steel cassettes?

The reason it is not that way from the factory is to decrease end cost to the consumer, and to cover their ass by making it more durable than it needs to be. Another reason is the process of manufacturing and tooling. For example if their was some weight to be removed from a part it is likely not possible without adding an additonal process. Not everyone wants to pay for that.
Spend the large amount of time you would spend drilling holes in a cheap cassette doing something to make some money. Use that money to buy a lightweight cassette, and come out ahead in the end.
 

·
Registered
Joined
·
358 Posts
... and here we are in the weight weenie world...

nowadays you would rather buy than make an effort to lighten your bike... working more hours to buy parts rather than to actually work on and ride our bikes.

Chris.
 

·
ACHOO
Joined
·
4,489 Posts
This is a weird thread.

1. The OP posted his question 5 years ago. I hope he's a dentist by now.

2. Many of us have day jobs when not being weenies. That means I can't spend 30 hours of hole drilling, even though that sounds fun.

3. At the end of the day, as Rocky mentions above (5 years ago), the resulting steel part is still probably heavier, and now weaker.

I'm not opposed to putting in time to lighten my bike, but sometimes spending cash makes sense.
 

·
Registered
Joined
·
150 Posts
You're right, this is a wierd thread. But we're allowed those too ;)

When you've bought all the light stuff you want to afford, and you've finished a long day at work, and its cold and wet outside, then firing up the bench drill is actually quite relaxing.

Better than watching TV, and more fun than getting cold and wet pedalling in the dark.

Hadn't realised this thread was dug up from so long ago. Maybe the OP is now a successful dentist, and helping people lose weight by drilling their teeth for them.
 

·
bike rider
Joined
·
5,569 Posts
I just finished a serious weight weenie project with the help of an engineer. He made sure that nothing I did weakened parts. We didn't drill any holes but we did grind a lot of metal and cut bolts to exact length. The most fun parts were using a lathe to butt head tubes and bottom brackets and making carbon seatpost shims cuz the alloy ones weren't a secure fit (and the carbons weighed half as much).
 

·
Registered
Joined
·
150 Posts
Sounds like fun. Were you able to record the savings you made?

I've saved around 89g by drilling, sanding, shaving, grinding, and cutting parts

A further 90+g for bolt tuning, swapping steel bolts for Ti, Alu or Nylon.

For years I'd used £1 per gram as being the limit of my weight weenyness ($1.5 per gram) Then the limit sort of crept up, following the use of some creative man maths, until I found I was spending around £1.50 ($2.25) per gram, but over that just seemed stupid, or needed additional justification, e.g. I needed better brakes, so the cost of that wasn't subject to my personal weight weenie spending limitation.

Saving 89g has therefore saved me over $200. Isn't man maths brilliant :cool:
 
1 - 20 of 22 Posts
Top