Cube saddle bolts

[billybunter]

Was looking for help from you wonderful people
Cube Kathmandu hybrid pro 500

Saddle bolts are damaged. One bent, the other sheared off

Trying to source replacement.
Rather keep with Allen key heads rather than have traditional nut & bolt replacement

Appreciate your help

[Jdsk]

Is that change in diameter half-way along by design or from damage?

Jonathan

[gregoryoftours]

Looks like a standard 35mm caphead screw, preferably one without full length thread. If it takes a 4mm Allen key it's an M5, if 5mm Allen fitting it's M6. Considering it's for a saddle clamp and fairly safety critical I'd go for 12.9 steel rather than stainless.

[billybunter]

Do you know where I could source these from?

[Jdsk]

Kays:
https://www.kayfast.co.uk

Namrick:
https://www.namrick.co.uk

Jonathan

[gregoryoftours]

Any fixings supplier, but for small numbers I often just go to eBay. Eg https://www.ebay.co.uk/itm/153749421574
One of the few that seems to have 35mm in stock. Just double check on the size, from your photo it looks like the screw is 35mm without the head, which is the measurement you want, and M5 is 5mm diameter of the thread (normally accompanied by a 4mm Allen fitting for this type of screw).

[billybunter]

Appreciate the help

[531colin]

It looks to me that there has been a significant bending load on those bolts.....this is caused either by the design of the seat clamp, or the way you are setting it up.
Replacing the bolts is all very well as far as it goes, but I can't be certain that new bolts, even high ten. bolts, will be a permanent fix, and there are occasions where the saddle coming loose is unpleasant, and even dangerous.
A photo of your seatpost, or a link to it, would be useful.
Is this it? https://www.bikester.co.uk/cube-kathman ... rm=1281327

[Jdsk]

It looks to me that there has been a significant bending load on those bolts.....this is caused either by the design of the seat clamp, or the way you are setting it up.

Yes, I don't understand the markings on the portion next to the head... are they wear on unthreaded shank or are they damaged thread?

Jonathan

[531colin]

I think its a plain shank marked by being screwed through an accurate clearance hole at an angle.

[Jdsk]

Thanks

Jonathan

[slowster]

Further to 531Colin's comment about the signs of there having been a significant bending load on those bolts, there should normally be a curved washer on the bolt. The convex washer and the matching concave surface of the seatpost allow the bolt to tilt as changes are made to the adjustment of the saddle.

The broken bolt visible in the corner of the first photograph looks like it might only have a thin flat washer instead of a more substantial curved washer.

[531colin]

From the OPs posting history, it looks like this bike is about a month old.

[Paulatic]

Or possibly a year old.

[531colin]

Damn, am I a year older already?