Any bidy used CAD/FE ?

[02GF74]

The lighter a set of wheels, the more expensive it becomes to save the few grammes.

I would like to see effect of drilling extra holes in the inner box section of a rim. If you take a box section rim like this Mavic, the outer sectionhas the holes for the spoke nipple eyelets ; the inner wall will have holes drilled in to allow the spoke nipples to be inserted as well as tightened via a screwdriver.

Clearly if Mavic feel it is ok to drill holes in the inner rim for the nipples, then how many more holes can be drilled without sacrificing strength? .... but then, if it was that simple, why don't they do that so knock more weight off?

So can somebody withg CAD FE (Finite Element) do an analysis on the effect of adding 2 or 3 10 mm holes in between the original spoke access holes? (yes, easier said than done).

In my opinion, the main strength is going to come from the ouer section as that is where the weight hangs from and side walls so inner section is not as critical - I could be wrong , hence the question. Also the holes will not be next to the spoke so there is less stress in those areas - kinda confirmed by Mavic shaving the rim and sidewalls in their CrossMax SLR.

(yes, I know this is not gonna make a huge difference to weight, I estimate IRO 12 g for a rim with 2 extra holes between the spokes but hey, why not....???)

 

[RecordAceFromNew]

You have asked a very interesting question, but I wonder if the effort required (I have some experience in FE, admittedly it was nearly 30 years ago...) will justify the result if potential weight reduced is of the order of 12g (or in the case of the XM719 shown 2.6%). Also what a FE assessment would not be able to evaluate on its own is the effect on crack formation and propagation, which can be significant for alloy.

I know it is not an answer to the question you asked, but have you considered lighter rims (all the X and XC series by Mavic are lighter) or e.g. Stans ZTR Crest (which is considerably lighter than any of the above)? Finally I would expect tyre, tube/tubeless and spoke choice will also likely be more fruitful exploration.