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Aluminium frame + Dremel = How many grams lost?

Posted: Sun Jan 29, 2017 1:35 pm
by SABARRAS
Hello everyone,

I'm new to the site and would like your advice on a bike build that I'm working on.

I bought a 51cm Planet-X Galibier SL aliminium frameset like this: http://www.planetx.co.uk/i/q/FRPXGAL/pl ... d-frameset

They claim a weight of 995g but the actual weight was a rather disappointing 1135g.

I have a SRAM Red Etap groupset and intend to respray it so I was going to see how much unnecessary weight I could remove without damaging the structural integrity.
I suspect that removing the cable guides with a Dremel and the pewter head badge will get me close to 1100g.

After removing the paint, I was going to Dremel/file the bulging welds flat, remove all the weld ridges (without digging too deep), the front derailleur support can be slimmed down a bit (the area welded to the frame)

Then I noticed that inside the head tube and bottom bracket, there are some holes that line up with the top and down tubes, it looks like I could remove quite a lot of aluminium if I carefully make those holes larger - the material within the tube intersection welds seems unnecessary. Then aluminium or titanium hanger bolts might save a few extra grams.

Has anyone every attempted something like that?

What would your estimate of the weightloss be after performing all the above?

Aluminium frame + Dremel = How many grams lost?

Posted: Sun Jan 29, 2017 1:35 pm
by Weenie

Re: Aluminium frame + Dremel = How many grams lost?

Posted: Sun Jan 29, 2017 2:32 pm
by audiojan
If you're unlucky you can save 1135g. I wouldn't start chopping it up without understanding structural integrity.

Re: Aluminium frame + Dremel = How many grams lost?

Posted: Sun Jan 29, 2017 3:14 pm
by SABARRAS
audiojan wrote:If you're unlucky you can save 1135g. I wouldn't start chopping it up without understanding structural integrity.

Of course! There is a risk of messing up.
The welds on the frame look well done with generous fillets all round, they are actually quite smooth already, I 'm talking about removing the parts where there are imperfections and clearly excessive amounts of weld - not digging in too deep.
I've done a bit of research on weld smoothing and if done correctly, it can actually strengthen the frame by removing "stress raisers"
https://www.hera.org.nz/Story?Action=View&Story_id=1092
http://singletrackworld.com/forum/topic ... ooth-welds

Re: Aluminium frame + Dremel = How many grams lost?

Posted: Sun Jan 29, 2017 8:48 pm
by BRM
Your assumption that you can shave 35 grams we can discuss, but when we go with that thought:

What is 35 grams? Is it worth the hassle? Don't come with unintelligent text that this is WW.
Be real. 2 average envelopes with 2 A4 letters in it weight more . . . . .

Thats the weight you're bothering.

Imo, pretty senseless. Because you never ever will notice such a difference in weight.
Stop looking through tubes, try to see the total picture of things, please.

Re: Aluminium frame + Dremel = How many grams lost?

Posted: Sun Jan 29, 2017 10:46 pm
by bm0p700f
If you want a lighter frame buy a lighter frame.
You will spend hours and remove 35g. You have potentially weakened the frame for what exactly.

Re: Aluminium frame + Dremel = How many grams lost?

Posted: Mon Jan 30, 2017 12:16 am
by F45
I would drill the seatstays and seat tube. Those tubes are almost superfluous anyway.

Re: Aluminium frame + Dremel = How many grams lost?

Posted: Mon Jan 30, 2017 4:31 am
by SL1
Are you planning to strip the paint off before re-painting it ? Even if you do that. a new primer, paint job and lacquer could easily result in adding more weight than before.

Once you cut the cable guides off, the frame will be electric compatible only and it will effect the resale value if you try to sell it (yes that day will come). Planet X carbon frames dont hold much value as it is. Alloy frames even less.

It's alot of work for such little savings. Do it for aesthetic reasons not weight saving.

If you bought the blue, i think the head badge and blue paint look quite snazzy. I'd keep those.

Re: Aluminium frame + Dremel = How many grams lost?

Posted: Mon Jan 30, 2017 5:01 am
by LouisN
Bad idea. Wrong thinking.

It's actually a very nice weight for such a frame. Close to the lightest Cannondale CAAD's, and Trek Emonda ALR's of this world.
Build the thing, and ride it.
There are alloy frames ( and CF too) that have heavy paint coatings. Not shure about the Planet x one.
Maybe you can strip the frame and have it powder coated. Don't know if the heating process can harm the aluminium or welds, as I am not a tech specialist. The fork, you can alos gently strip it and give it a light coat of clear or wax, as it's been done here ( 303 finish comes to mind).
The other weight savings you will have fun to "gain" well, is all the rest of your build :beerchug: .

Louis :)

Re: Aluminium frame + Dremel = How many grams lost?

Posted: Mon Jan 30, 2017 8:43 am
by Marin
Don't do it, the frame is very light already.

If it's painted you could remove the paint but then you'll have to deal with corrosion.

Claiming a sub-1kg weight is stupid by Planet X.

Re: Aluminium frame + Dremel = How many grams lost?

Posted: Mon Jan 30, 2017 10:02 am
by SABARRAS
Thanks for your replies. The consensus is clearly - DON'T DO IT!!

I thought there would be more curiosity here about what is possible, you all seem very sensible but you are probably right, I doubt that I could remove more than 50g in total.

I'm going to strip the frame and remove the gear cable guides for sure, then respray it in my own choice of paint job, I'm not bothered about selling it later.

Having said that, I will keep an open mind when I inspect the bare aluminium.

Re: Aluminium frame + Dremel = How many grams lost?

Posted: Mon Jan 30, 2017 11:55 am
by lone wheeler
Looks a decent frame and forks for the price, any pics of it in the real world before you mess around with it?

Re: Aluminium frame + Dremel = How many grams lost?

Posted: Mon Jan 30, 2017 12:14 pm
by huffington
take a look at this, they used to do it in the 70s and 80s, but those components were already very thick and heavy, and they did it on stuff like levers, derrailleurs, chainrings. I wouldn't do it to a frame, it could go wrong

Re: Aluminium frame + Dremel = How many grams lost?

Posted: Mon Jan 30, 2017 12:43 pm
by SABARRAS
lone wheeler wrote:Looks a decent frame and forks for the price, any pics of it in the real world before you mess around with it?
Yeah it looks good (Not my bike by the way)

Re: Aluminium frame + Dremel = How many grams lost?

Posted: Mon Jan 30, 2017 12:51 pm
by SABARRAS
huffington wrote:take a look at this, they used to do it in the 70s and 80s, but those components were already very thick and heavy, and they did it on stuff like levers, derrailleurs, chainrings. I wouldn't do it to a frame, it could go wrong
Ha ha, all those new nooks and crannies to drive you mad when cleaning.

I found this:
http://www.bikeradar.com/forums/viewtop ... t=12956986

and This:
http://singletrackworld.com/forum/topic ... ice-needed

and this:
http://forums.mtbr.com/frame-building/g ... 23593.html

It does seem good practice to flatten any ridges and bumps - my frame appears to have been constructed using the double pass welding technique.

Re: Aluminium frame + Dremel = How many grams lost?

Posted: Mon Jan 30, 2017 1:13 pm
by mattr
Just be careful not to put too much heat into the weld, or any gouges.
Doubling up on HAZ and adding stress risers isn't a good idea.

Re: Aluminium frame + Dremel = How many grams lost?

Posted: Mon Jan 30, 2017 1:13 pm
by Weenie