Drilling holes in a steel bike frame

[Accy cyclist]

A friend of mine has bought a bottle cage,only to find there aren't any holes to screw the cage to the frame. She says she's going to ask someone to drill two holes into the downtube. I told her that it might affect the strength of the frame. Am i right? I'm almost certain the frame is steel,though it could be aluminium. The bike's about 30 years old.

 

[Drago]

I wouldn't recommend it. Why not just use clips, or get a handlebar mounted model?

And when she's drilled the holes, then what? Does she have a rivnut tool, or is she capable of welding in bosses?

 

[winjim]

She'd then need to install those threaded doodads to actually mount the cage to. I'm sure a proper frame builder could do it but it seems a lot of hassle. Just get a band on.

 

[Accy cyclist]

I wouldn't recommend it. Why not just use clips, or get a handlebar mounted model?

And when she's drilled the holes, then what? Does she have a rivnut tool, or is she capable of welding in bosses?

I will put all suggestions to her. I told her it seems a bit extreme,just so you can have a water bottle. I did suggest using tape or tie backs,but she likes the idea of holes in the frame,for some reason.

 

[biggs682]

Get a band on style no holes to drill

 

[si_c]

If you drill holes in the frame, that's what you end up with, holes in the frame. A steel bike will have tubes no more than a couple of mm thick. You'd need to then have the bolts fitted as mentioned above, which won't be cheap.

There are plenty of options, I got one from elite for my 70s Peugeot, which has no bosses, cost less than a tenner from Halfords.

 

[Smokin Joe]

Get a band on style no holes to drill


View attachment 404397

You need to paint that back door instead of messing about with bikes.

 

[mcshroom]

I wouldn't drill into the frame, and anyway you'd still need to install some rivnuts. The job starts to become a bit expensive for just fitting a bottle cage then. Instead I would use these: -
https://www.ebay.co.uk/i/192467353607

They are the same as @biggs682 has on that frame and held a second bottle on the set tube of my audax bike fine for a while.

I've also used the Elite ones from Halfords, which work just as well IME, and have screw in mounting holes rather than tying the cage to the frame so will take the fashion carbon/plastic cages that don't have those bits of plate to clamp. They don't look as nice though IMHO.

If they use clamped mounts, make sure they put some tape under them to prevent paint damage.

 

[Alan O]

Absolutely yes, tell her to stop drilling now. The thickness of the tube is simply not enough to screw in to (steel tubes are very thin, and aluminium is soft), and she'd need proper mountings fitted - with either metal, you don't just drill and screw into it.

As others have said, you can get strap-on bottle mounts - I used them for years on an old bike.

 

[KneesUp]

Drilling holes in the frame won't unduly change it's strength if you then fill the hole with something (a rivnut or nutsert - which you will need so there is a thread) If it did, we'd here more about bikes failing where the bottle cage or pannier mounts are.

You can get M5 inserts quite cheaply - about 10p each of you buy 50 off eBay. You friend will need a rivet tool that can take rivnuts.

EDIT - drilling into a narrow cylinder may be quite tricky - if your friend slips with the drill it might get messy. An LBS worthy of the name will be able to do it I'm sure.

 

[Dave7]

I will put all suggestions to her. I told her it seems a bit extreme,just so you can have a water bottle. I did suggest using tape or tie backs,but she likes the idea of holes in the frame,for some reason.

Maybe she wants holes drilled to make it lighter so it will go faster.
On the other hand

 

[Accy cyclist]

Maybe she wants holes drilled to make it lighter so it will go faster.
On the other hand

 

[Accy cyclist]

I'll tell her that one. I don't know if she'll like it though.

 

[Gravity Aided]

Drilling holes and installing rivnuts may look simple, but doing a proper job of it requires skill and patience. Banded holders are easier and simpler.

 

[biggs682]

You need to paint that back door instead of messing about with bikes.

That's the entrance into bike heaven