Threaded Hole Underneath of Top Tube

[chris-suffolk]

My bike (well one of them) has the same. It's a racing frame, and I was always led to believe it was for the racing numbers, as mentioned by another post above

 

[Ming the Merciless]

Email the manufacturer and ask them?

Don't be silly 🙃

 

[Big John]

It might be for a pump clip.

Some pumps only require one, the other end being curved to locate against a frame tube.

That gets my vote too I think. Not sure about the race number theory. When I raced in the LVRC and TLI we wore our numbers on our backs. I have seen some events with numbers shown on the frames though so by teatime I might change my mind 🤔

I used to be indecisive but now I'm not so sure 🧐

 

[CanucksTraveller]

Quite a few tourers have a pair of bosses right there, usually intended as a mount for a "fuel tank" frame bag or an extra bottle cage. Stanforth and Bombtrack (and probably many others) have them. With it being a single one I'd say it's more likely intended for a pump.

It's not for a race number, when race numbers used to be mounted on frames there was a permanent brazed on "tab" that had a little bolt and nut on it, and the number plate was attached onto that.
Race numbers go behind the seat post now, or on jerseys.

 

[Chislenko]

Email the manufacturer and ask them?

Funnily enough that's exactly what I did first thing this morning, will update when they reply.

 

[chris-suffolk]

It might be for a pump clip.

Some pumps only require one, the other end being curved to locate against a frame tube.

I'm definitely of the opinion that it's NOT for a pump. Mine is on a light weight carbon racing bike, and I very much doubt that many racing roadies carry a frame pump.

 

[T4tomo]

if it were on an old steel audax, then pump may be an option, but I reckon not. Its odd there is only one, as for luggage mounting 2 would be needed to do away with the velcro completely, There are some frame bags that bolt mount, but tend to be manufacturer specific to fit their own frames, or water bottle boss spacing on top of the top tube for "tank bags" / additional bottle cage

 

[weareHKR]

It could be used to fill the frame with cocaine, plugged & then taken abroad to use on your holiday... ... Well, it's as good a guess as I've seen so far...

 

[Chislenko]

So, had an answer from Ridley bikes which said

"Dit was oorspronkelijk gemaakt met de bedoeling van een fietspompnokje aan vast te maken!"

Which Google translate comes up with the following.

"This was originally made with the intention of attaching a bicycle pump skirt!"

That's cleared that up then 🤔