Boardman carbon frame brake fitting.

[Gillstay]

Hi. This bike came in the smallest bits a teenager could turn it into. Now fitting the brakes and they don't seem to push fit into the frame and have a nut on the back as I would expect. There appears to be a thread in the frame which I can turn the caliper to screw it in with. Is this correct ?

 

[fossyant]

Shouldn't be, could be full of crap. You may need a longer nut to reach the thread on the calliper ?

 

[figbat]

This is a recessed mount caliper rather than the traditional nutted mount.

 

[fossyant]

This is a recessed mount caliper rather than the traditional nutted mount.

Yes most bikes have been for years, even my early 90's bikes are all recessed 'nuts' as such.

 

[oldandslow]

And secure with an Allen key, which no-one seems to have mentioned. You don't turn the caliper - just turn the nut with the key.

Available in various lengths to suit holes of differing depths. Can't remember what the standard sizes are.

 

[cyberknight]

i have 2 Boardman bikes one carbon of a similar vintage to that bike and an older alloy with the same seat stay design , there is a recessed nut in the back that you screw into which might be missing

 

[biggs682]

i have 2 Boardman bikes one carbon of a similar vintage to that bike and an older alloy with the same seat stay design , there is a recessed nut in the back that you screw into which might be missing
View attachment 825350

Or it could be seized in the frame as i had a few years back

 

[cyberknight]

Or it could be seized in the frame as i had a few years back

indeed, i found i needed extra washers between the caliper and the frame as the bolt was slightly too long to be able to tighten the nut properly

 

[Webbo2]

indeed, i found i needed extra washers between the caliper and the frame as the bolt was slightly too long to be able to tighten the nut properly

The nuts come in different lengths I’m fairly sure I’ve cut then down in the past.

 

[Gillstay]

If anything the bolts section is too short on both and the recessed nuts have a washer incorporated into the design so don't seem to want to go in very far. It may them that is wrong, and giving me the wrong idea.
Nothing is stuck in the frame, but the bolt sections going in are very tight.
Thanks for your thoughts.

And secure with an Allen key, which no-one seems to have mentioned. You don't turn the caliper - just turn the nut with the key.

Available in various lengths to suit holes of differing depths. Can't remember what the standard sizes are.

These calipers have to be turned to get them to go in. They won't push in. Wish i had been there when the lad took it all to bits.

 

[cyberknight]

The nuts come in different lengths I’m fairly sure I’ve cut then down in the past.

they do although i meant the bolt that is attached to the caliper that can come in different lengths too

 

[Gillstay]

Well trying a longer brake in there doesn't work either. Thats as far as it will go. Also now I have pushed a file through and screwed in the brakes a few times you can see the insert in the frame. Never come across this before. Interesting.

 

[SuffolkBlue]

Well trying a longer brake in there doesn't work either. Thats as far as it will go. Also now I have pushed a file through and screwed in the brakes a few times you can see the insert in the frame. Never come across this before. Interesting.

View attachment 825467

View attachment 825468

Yes, I've never seen that before either? Is it possible that the thread visible in the frame is the remains of the recessed nut which is seized in the frame and the "teenager" has rounded off the hex fitting at the other end???

 

[fossyant]

Yes, I've never seen that before either? Is it possible that the thread visible in the frame is the remains of the recessed nut which is seized in the frame and the "teenager" has rounded off the hex fitting at the other end???

This is what I'm thinking too. Try a hex key from the other side to see if the recessed nut is trapped in there - can you 'turn it. Other option is to see if you can 'tap' it out - use caution.

 

[Ajax Bay]

Nothing is stuck in the frame, but the bolt sections going in are very tight.
These calipers have to be turned to get them to go in. They won't push in.

it [a recessed nut] could be seized in the frame as I had a few years back

I suggest that the very fact that "the calipers have to be turned" and they "won't push in" means there is 'something' "stuck in the seatstay 'bridge' hole.

We can see the threaded nut inside the 'ole, no? See @biggs682 experience.
I don't think the OP will be able to extract this errant nut by 'unscrewing it' with an allen key per @fossyant : why would turning it have any extraction effect? Might be a useful 'loosen' though.
Get a bolt the same OD (?M5) and tpi as the one on the caliper, screw it in 'as far as' and 'tap' with a rubber mallet, supporting the seatstay securely.