Dropper Post

will420

My external cabled reverb has finally died so i am considering replacing it with a stealth reverb which i won at an enduro race. However, my bike does not have internal cabling so i was wondering whether is is a bad idea to drill a small 5mm hole in the frame? and if so where is the best place to drill it? the bike i have is a 2012 giant trance x0.
Thanks in advance

rockmonkeysc

I wouldn't do it if it's still under warranty. If that's not a problem then near the bottom of the seat tube and fit a gromit so the hose doesn't get damaged.

The Rookie

A friend has drilled a few frames, as pointed out you need to get a grommet and drill for that size, it's not at all difficult , just don't drill too close to the bottom of the sea tube, allow for a sensible curve of the hose from the downtube.

sheepsteeth

hmm.

if someone showed us a picture of their bike with a 5mm hole punched in it from an accident, im sure we would be talking about frame repair or replacement.

if the bike didnt start with a hole, i wouldnt be drilling a new one in to it.

paul.skibum

Someone in Whistler this summer was selling a bike which he listed a selling point as having been retro fitted with a stealth dropper by having a hole drilled in the frame. The fella said he had been told by the manufacturer it was OK to do it and where (including measurements) he should do it.

I still though it sounded a terrible idea.

That said, I don't think most alloy bikes with stealth routing have anything more complex than a hole drilled in them, so what the hell.

rockmonkeysc

[url=http://www.bikeradar.com/forums/viewtopic.php?p=19690608#p19690608]sheepsteeth[/url] wrote:

hmm.

if someone showed us a picture of their bike with a 5mm hole punched in it from an accident, im sure we would be talking about frame repair or replacement.

if the bike didnt start with a hole, i wouldnt be drilling a new one in to it.

A hole punched in an accident will spread and tear because it effectively is torn rather than cut and it's a shape which will create stress risers.
A small cut hole with a nice uniform, round shape won't significantly weaken a frame. Choose a position where the frame has little stress and you are only doing the same as the manufacturer will do.

sheepsteeth

Well, if the amassed bike building expertise here is confident, im sure they wont mind chipping in for repairs to any damage caused by drilling a hole in a frame.

id be inclined to agree that there may well be no problems. i wouldnt want some one to take my advice to do it though.

To the OP.

You are asking entirely the wrong people here. Get in touch with Giant, find out what they think then let us all know for future reference.

rockmonkeysc

Giant will say no to any mods at all. It's not worth their while investigating the stress dynamics around the new hole and want no liability for anyone doing a half arsed job.
If I was in the same position I would break out the drill but I spend a good proportion of my working life modeling stresses in metal products so have a good idea where the low stress areas are (about two inches above the bb on the seat tube in this case) and I'm confident in my ability to do a reasonable job. I would happily do it to my Transition if it didn't already have a hole.

Clockworkmark31

[url=http://www.bikeradar.com/forums/viewtopic.php?p=19690827#p19690827]RockmonkeySC[/url] wrote:

Giant will say no to any mods at all. It's not worth their while investigating the stress dynamics around the new hole and want no liability for anyone doing a half arsed job.
If I was in the same position I would break out the drill but I spend a good proportion of my working life modeling stresses in metal products so have a good idea where the low stress areas are (about two inches above the bb on the seat tube in this case) and I'm confident in my ability to do a reasonable job. I would happily do it to my Transition if it didn't already have a hole.

Fully agree, a manufacturer will not commit to anything being modified due to so many variables that could go wrong. They are only protecting the brand.

But I agree with the above. If you aren't afraid do it, but make sure you understand stress and fracture points before doing so.

Not being too familiar with droppers (on my wish list) have you not exhausted all other routes first?

sheepsteeth

Of course giant will say no mods at all.

That's entirely the point im making.

If one was to drill their frame there is no guarantee that it will be fine, there is just an assumption that it should be fine. A big difference when glibly slinging advice about.

For what it's worth, most holes iv seen in frames aren't a simple 5 mm hole, they are bigger and oval shaped to allow the hose a more natural exit. However,My bike has a metal housing bonded in to the hole in the frame to reinforce whats missing so it's probably safe to assume that a simple hole isn't always the best answer and in fact, I think giant's hose exit tends to be near the head tube on their more recent bikes.

mike hunts alpine

Simple sell/swap post for an external one.

ilovedirt

I'd probably do it, personally. Stress tends to build up at sharp points/angles, which is why you rarely ever see sharp angles on anything load bearing, they're rounded off. It's also why drummers drill holes at the end of cracks in their cymbals - circles spread load evenly and are very strong, they stop cracks propagating.

My point being, a small circular hole that's smooth and burr-free is unlikely to create any problems. It'll void your warranty, but it should be fine.

That said, don't take my word as gospel. I certainly wouldn't do my own frame unless it was a good year or two old and well out of warranty.

The Rookie

Stress increase as the radius decreases, a crack has a tint end raid is and raises the stress significantly (stress concentration factor if you want to google it) drilling a hole increases that radius (it's nothing to do with distributing it evenly) and is used on many applications including commercial airliners.

The weakest point on an aluminium frame is at welds, that is why tubes are butted, more metal where it matters, less to save weight where it is not, drill at least 25mm from the nearest weld and it will be fine.