Is it safe to drill chainstay bridge?

[snilard]

I would like to fix my new front mudguard to chainstay bridge. The best way would be to drill ~3,5 mm hole thru the bridge and bolt plastic mudguard holder there.

Is it safe to drill chainstay bridge?

 

[LarryOz]

I would like to fix my new front mudguard to chainstay bridge. The best way would be to drill ~3,5 mm hole thru the bridge and bolt plastic mudguard holder there.
Is it safe to drill chainstay bridge?

Probably - but if you can take a picture of your chainstay and then edit it with an arrow or pointer to show exactly where you would like to drill the hole.

 

[snilard]

Probably - but if you can take a picture of your chainstay and then edit it with an arrow or pointer to show exactly where you would like to drill the hole.

I cannot tako photo right now so I used one from Cruzbike web site. I have red V. I would say that this one is size L while mine is M. I would say that my bridge is bit thicker.

 

[LarryOz]

I am not expert in structural integrity but I think as long as you keep the diameter of your hole to less than 1/3 of the thickness of the bridge you are going to be fine. Hopefully Robert can chime in with his thoughts.

 

[RojoRacing]

I'd dill a 5mm or smaller hole in that without a second thought, that brace is overbuilt as it is but don't expect anyone directly connected to cruzbike to approve any such drilling of the frame. Whether or not they believe it safe as a company you'll almost never get them to recommend adding holes due to liabilities sake.

 

[RojoRacing]

My one recommendation is measure 3 times and think about it hard before doing it to make sure your hole is the correct size and in the right stop. You can always drill it bigger but going smaller isn't an option without serious skill with a welder and some quality paints

 

[LarryOz]

Whether or not they believe it safe as a company you'll almost never get them to recommend adding holes due to liabilities sake.

Good point Jason!

 

[Mathew Fy]

I would just use a p-clamp of the appropriate size. It’s secure enough for a fender, reversible, and doesn’t interfere with integrity.

 

[snilard]

I would just use a p-clamp of the appropriate size. It’s secure enough for a fender, reversible, and doesn’t interfere with integrity.

The hole thru the bridge would be perfect solution from dimension and clearance perspective.
My mudguard holder looks like this but is made out of plastic: https://www.compasscycle.com/shop/components/fenders/honjo-sliding-bracket/ It is made to be bolted to a bridge. The mudguard can be slided up and down by hand in the holder. What is perfect for my experiments with boom length.
P-clamp would fix mudguard to exact position of the boom. And changing of boom length would mean redrilling/rebolting of mudguard.

 

[billyk]

The hole thru the bridge would be perfect solution from dimension and clearance perspective.
My mudguard holder looks like this but is made out of plastic: https://www.compasscycle.com/shop/components/fenders/honjo-sliding-bracket/ It is made to be bolted to a bridge. The mudguard can be slided up and down by hand in the holder. What is perfect for my experiments with boom length.
P-clamp would fix mudguard to exact position of the boom. And changing of boom length would mean redrilling/rebolting of mudguard.

Yes, but by the same token, changing the mudguard (they wear out before the frame) might require a different mount. Then you'd've made a permanent mod for a temporary add-on.

The P-clamp is an excellent idea, at least to try out the mudguard setup. Maybe you can make it work for the adjustable mudguard. Maybe it's not so hard to loosen and adjust the P-clamp when needed. Maybe you can do your boom-length experimenting without the mudguard, after which the length will be fixed ... all in all, I'd be VERY cautious and deliberate before drilling into the frame.

 

[snilard]

Yes, but by the same token, changing the mudguard (they wear out before the frame) might require a different mount. Then you'd've made a permanent mod for a temporary add-on.

The P-clamp is an excellent idea, at least to try out the mudguard setup. Maybe you can make it work for the adjustable mudguard. Maybe it's not so hard to loosen and adjust the P-clamp when needed. Maybe you can do your boom-length experimenting without the mudguard, after which the length will be fixed ... all in all, I'd be VERY cautious and deliberate before drilling into the frame.

You are right, I will think about some kind of clamp.

 

[benphyr]

Hi @snilard,

If you have this type of bracket

(https://www.niagaracycle.com/categories/planet-bike-bridge-hardware-kit-for-road-fenders)

then use two small zip ties through those little channels (parallel to the tire) in the outside of the bracket similar to the orientation of these zip ties. Through the bracket channels and over the bridge.

(https://www.niagaracycle.com/categories/cannondale-headshock-adaptor-for-sks-shockboard-fender)

to hold bracket to the bridge. As long as everything isn't too ridiculously tight you should be able to even adjust things and slide the fender bracket along the fender without removing fender or zip tie or anything.

(As a not as good alternative, I have drilled two holes centred longitudinally in the mud guard a little further apart than the bridge and used a single zip tie to attach to around the bridge of a front suspension that did not have any mounting point.)

 

[snilard]

Hi @snilard,

If you have this type of bracket

(https://www.niagaracycle.com/categories/planet-bike-bridge-hardware-kit-for-road-fenders)

then use two small zip ties through those little channels (parallel to the tire) in the outside of the bracket similar to the orientation of these zip ties. Through the bracket channels and over the bridge.

(https://www.niagaracycle.com/categories/cannondale-headshock-adaptor-for-sks-shockboard-fender)

to hold bracket to the bridge. As long as everything isn't too ridiculously tight you should be able to even adjust things and slide the fender bracket along the fender without removing fender or zip tie or anything.

(As a not as good alternative, I have drilled two holes centred longitudinally in the mud guard a little further apart than the bridge and used a single zip tie to attach to around the bridge of a front suspension that did not have any mounting point.)

Yes, holder looks same. Good idea I will give it try. Thanks