Drilling an old Raleigh steel frame and forks.

[Little Jim]

Miss LJ has a Raleigh mixte frame which she is trying to update and in the quest to be able to stop the machine has  bought some modern Shimano callipers. The problem is that the holes in the frame and forks are slightly too small for the bolts, probably by 1mm or 2mm.  SJS (who she bought the callipers from) have told  her not to drill the frame but to use longer bolts on the callipers and a nut on the outside of the frame and forks, but it looks to me like there would be enough metal, especially in the forks, to drill them out. Does anyone have any experience of doing this?

[LittleWheelsandBig]

https://sheldonbrown.com/calipers.html
I've drilled out front and rear but prefer drilling just the front. You can now get very long Allen nuts that you could use with a rear brake on the front and then fit the front brake on the rear with a hex nut.

[mcshroom]

I'd be tempted to get one of these from SJS. If she has the old brakes then she can reuse the half-moon washers and nuts from them.

[Karla]

I've drilled out frames and forks before, nothing went wrong.

[Brucey]

It is without doubt the best idea if (as SJS suggest) you convert the brakes to a nutted fit using the long tektro bolt mentioned above.

But before you do anything else, do check that the new brakes have enough reach to work on your bike anyway. IIRC shimano make lots of brakes but only two dual pivot calipers even have a reach of 57mm, being BR-R650 and BR-R450. All the other brakes they make have a maximum reach of 52mm, I think.

Both types of brake would be rather shorter than would usually fit on a Raleigh Mixte frame; BITD the typical setup would be to have a 610 type caliper at the front and a 750 type caliper at the rear; both have more reach than 57mm.  You might find that a 57mm reach caliper is OK at the front but not at the rear on your frame.

IIRC there is a longer reach Tektro DP caliper made in nutted fit which may be suitable. Spa cycles sell these, amongst others.  If the reach isn't quite right anyway, it is a no-brainer just to get those TBH.

BTW brakes that are 'just long enough' are a dumb idea if you want good power. In any given brake the mechanical advantage (MA) varies from very good (with the brake blocks in the top of the slot) to nothing like as good, if the brake blocks are in the bottom of the slot. The MA reduces by about 30% in most DP calipers, which is a huge amount.  By contrast if you start with longer reach brakes, they have longer arms with more leverage so the MA at (say) 57mm reach is more with a 65mm drop brake than it is with a 57mm drop brake.

Note also that the brake levers need to be the right ones too. Nearly all shimano STI models launched post 2008 (which have 'New Super SLR' cable pull) have a much reduced lever MA and only work properly with matched calipers. Shimano don't make perfectly matched 57mm drop calipers; the two models they do make are not perfectly matched to modern STIs  and really were designed to work with the previous generation of brake levers (~1992 to 2007 launch dates).

 So if you use BR-R450/R650 at full reach with modern (post 2008) STIs, you can expect a relatively poor brake, by modern standards.

cheers

[rogerzilla]

Centre pulls work better than dual pivots for very long reach brakes, provided the "horseshoe" of the centre-pull is stiff enough.  I'm very happy with my Dia-Compe GC700 brakes (70mm reach) although they were not cheap.  I use them with Dia-Compe 188 levers.

Drilling a fork for an allen key brake is trivial but drilling a seatstay bridge is tricky as you have to drill it from the seat tube side only.  Either use a right-angled drill attachment, if you have one, get a shop to do it or just leave it undrilled and buy two front allen key brakes, using a nut and washers on the rear one.  Or forget drilling at all and use nutted brakes.

The GC700 brake, incidentally, can be used front or rear, allen key or nutted, as it comes with a choice of two centre bolts (which just push in by hand), allen key nuts and normal nuts.

[zigzag]

just to add that shimano makes (used to make?) br-a550 caliper, a shiny version with a 57mm drop. my preferred method for steel frames was to use two front calipers, one at the back with a nut and one on the front with a countersunk nut and the back of the fork drilled out to 8mm.

[clarion]

I have drilled a couple of frames.  Sometimes, you only need to enlarge one side of the hole.  There were no adverse events.

[Brucey]

BR-A550 calipers are better known as an RX100 groupset caliper. According to velobase they have not been manufactured since 1999, I think.  BR-R450 is basically the modern version of that.

cheers

[Little Jim]

Thank you for all your suggestions and advice.  I have pointed Miss LJ in the direction of this thread.  She also assures me that she has carefully checked the measurements and the Shimano callipers that she has got are long enough....