[metal] how to embiggen the hole?

[mattkime]

I'm putting modern brakes on this thing AND fenders. It would be helpful to make this hole a bit bigger but i could use some ideas on how to do it accurately and the best bit to use.

[deckeda]

I'd probably ask on a bike forum, where you might run into a mechanic whose done this many times.

But playing one here is fun, too!

1) Try a carbide bit at SLOW speed. Anything fast drilling into cromo steel is likely gonna shred the bit if done too fast.

2) Watch for cracks.

3) Pursuant to #2, acquire a spare fork from a more modern bike. If you just swap it in you'll also take the opportunity to possibly inspect or replace the headset, too. But don't ask me about threaded vs, threadless headsets here.

[iaJim]

They used to use this sort of bit for that on Orange County Chopper.

http://www.mytoolstore.com/klein/59001.html

[LyleH]

Seems to me that if you make that hole much bigger you're going to weaken the fork structure. LyleH

[btfc]

http://forums.bicycletutor.com/thread-2660.html
http://sheldonbrown.com/calipers.html

[Rolando]

I amused my girl and her best friend while installing some curtains. I explained I need to "ream" the drill hole!
Ream: Verb
To enlarge a hole, to bore a hole wider.

I responded to their giggles by advising them I am really good at the practice!

[Kate]

Embiggen, I love it!

Kate

[Filliam H. Muffman]

LyleH wrote:
Seems to me that if you make that hole much bigger you're going to weaken the fork structure. LyleH

:agree:

Are you doing this to install brakes that have the sleeved/recessed nut? Is that rust on the bottom headset bearing? :popcorn:

[davester]

I think you're opening yourself to a world of hurt and annoyance wanting to use a brake type that is not designed for that bike. Why are you doing this How about just buying some brakes with the long non-recessed bolts that work with your bike as is. They are still available: http://www.sheldonbrown.com/harris/brake-calipers.html . For mounting fenders you don't want the recessed bolts anyway. Going with so-called "modern" brakes (i.e. those with recessed bolts and otherwise no different from "non-modern" brakes) is going to cause you a whole slew of problems.

1. They are generally short reach and won't be able to adjust far enough so that the pads reach the rims. This is especially true if you're using an old inexpensive bike frame (I seem to recall that you were going to buy a Raleigh Grand Prix) and even more especially true if you're going to use 700C wheels on it.

2. You need to drill your fork crown and have to obtain a second front brake to fit on the back.

3. They won't work with fenders without buying expensive "Sheldon nuts", while the non-recessed bolt brakes will work just fine..

One more note...if you are referring to dual-pivot brakes as "modern brakes", note that they have a different mechanical advantage than standard centerpulls or sidepulls. This means that you will need to use a different set of brake levers with the mechanical advantage specifically matched to the dual-pivots.

[mattkime]

I've done my homework.

Yes, it would be easier if I bought nutted brakes but the only additional work is drilling this particular hole.

I'll swap the front and back brakes which allows the rear to work nutted since the bolt will be long enough. on the font i can install the brake nut inside the fork. the only problem with this is that I'd like to instal fenders using the Sheldon nuts that i currently own. Yes, they're pricy as far as nuts go but they're well worth it as far as brake/fender adjustment.