Drilling a Keirin Frame fork Need expert help please

General Help
1

Hi all here my situation i just got my new upgrade stratos keirin frame. Now i have a big problem i need to drill the front break hole in the fork , i have done it before on my mates bike for him and it worked all well but this time no my bike the crown is alot less room to drill. I have to run a break as i have been fined before not having one and if i hit someone they can charge me for not having a break any way im am NOT going to put one of the ugly clamp breaks on it so i must drill.I dont want a new fork as the frame and fork is beautiful.

here is my options so far
1/ there is 10mm play room and the bolt is 5mm thick so really 3mm on the bottom and 2 mm on the top of the bolt left if that makes sense is that going to be strong enough to hold
2/ 10mm play room get the last half of the bolt turned thiner say to 3.5mm so then it gives me more room to play with

i am building my dream bike now so i cant take no drilling for an answer so can any experts engineers out there please please help me with this as im fucked if i cant do it.
the frame is a stratos frame columbus also if that helps

2

Okay, firstly, this has been covered to death here. It’s like 10 posts down from your thread.

Secondly, The don’t make call those clamp on brakes [i]Keirin[i] brakes for nothing.

EDIT: Unlocked because it is slightly different than the other fork drilling thread.

Let’s stick to the engineering logistics of drilling a fork.

But seriously, drilling forks is crap… in my opinion. Clamp on FTW.

3

I am with JLN on that one, please keep from starting another heated discussion about whether drilling forks is ethical :roll: :stuck_out_tongue: and stick to discussing the possible structural consequences of drilling this specific fork crown. cheers
here’s a pic of his fork…

4

Hey, I’ve got a Masters Degree in Mechanical Engineering from Monash and honestly, looking at the image posted above, I would not recommend that you drill that fork.

Most Colombus tubing has a steel density of 7.85 g/cm3, this basically means that when heat is applied, which includes direct sunlight (riding during the day), anything thinner than 7.83cm / 3, i.e. 2.6cm is going to be prone to compositional failure, or in other words, stress cracks. You might be alright for a little while, but then one day when you’re riding down Swanston Street at 23km/h you’ll suddenly find yourself sliding face first across Bourke Street wondering what went wrong.

Hope that helps, sorry to be the bearer of bad news.

5

logistical/engineeringal/functional

who cares - drilling that would just be an act of vandalism. buy another bike that already has a drilled fork and hang that one on a wall (or sell it to me - how big is it?)

Buy another bike with a dril

6

More like good news for the fork

7

I have to agree with going with a clamp-on brake on this one mate

The rounded fork crown doesn’t allow for the brake to sit flush and I doubt that the drilled crown will be structurally sound :expressionless:

8

9

what’s the clearance like between tyre/fork crown?

i’ve been toying with using a setup similar to a quill stem, but upside down. so it goes in the through the bottom of the fork, and has a hanger which then comes out the front (or possibly behind :-o) to which the brake mounts.

pros: looks clean, easily removable, no fork drilling required.
cons: sufficient clearance required, questionable strength, non-existent.

10

serious getting another fork for your dream bike is not such a big deal, I replaced the fork on my Bridgestone frame for a good road fork chrome and the aesthetic and ride are still superbe.

11

Thanks for all the feed back, so it looks like it’s going to be clamp on which I don’t want,
with the clamp on how do they work I have seen some pictures with these on bikes and there got scratches all down the fork from the clamp , is this normal does the clamp move around I just don’t want to scratch the paint at all that’s why I was againt it , it looks like it slides up the fork to get it on.

12

Keirin brakes are fine, they work well with a good set of brake pads. To be honest they are not much more intrusive than a regular brake and you will hardly notice the clamp. In terms of leaving marks on the fork, it pretty negligable really as long as you do em up tight.

13

Let’s not forget that having enough space to drill the crown is only one consideration.

I’m no NJS expert but I’m tipping the fork has round track blades?

If so, it’s probably going to flex quite a bit under braking because round blades are not designed for braking forces.

It’s been covered all before (and recently too) so I’ll just say, get a road fork. It’ll still be your dream bike.

14

I have the dia comp leaver and that is shit if you are after braking peformance that being said I love mine. I think where alot of people go wrong with their brake set ups is using this type of leaver or cross style. Make sure you get a leaver that pulls the cable not pushes the outer and as said before chuck the standard pads and start again.

For the clamp on use Some old iner tube around the fork. plenty of grease on the threads to tighten up the clamp so you can tourque it up.

15

What are some nice keirin brakes out there I found dia bra 101 is there any others,
I was thinking of my frame is white so I might paint the clamps white so it blends in more and tape the inside to prevent damage. The brake won’t be used much as it’s for emerg and not getting finned, will take your advise on the lever cheers Rick

16

hidden talents!

17

I’ve got 2 of those cross levers and they work fine. Even with standard pads I reckon I could put myself over the bars quick smart.

18

I was just hoping someone took that post seriously and measured their fork crowns.

19

Just something I came across

20

This is a pretty good idea… get to work!