Brompton - has my rear triangle been dented by my seat post ?

[snazpizaz]

Hi

I was servicing my Brompton and i noticed that the seat post has been catching my rear titaneum triangle. (See images)

I think this has been occuring when i fold the rear wheel under the bike when temporarily parking and lower the seat post without releasing the centre frame-clamp and folding / hooking the front wheel to the side, which seems to be the way to align a tucked under rear wheel so the seat post can slide all the way down to the disc stop un-obstructed.

Anyway - there is a small circular dent on the titaneum rear triangle now but i am wondering if this was always there and the damage is just the superficial rub marks or if the issue has created this ciruclar dent ? Can folk check there Brommies and tell me if they also have a circular dent and it's just part of the design ? If it's not should i be worried ?

cheers
sp

 

[berlinonaut]

I was servicing my Brompton and i noticed that the seat post has been catching my rear titaneum triangle. (See images)

I don't think so.

I think this has been occuring when i fold the rear wheel under the bike when temporarily parking and lower the seat post without releasing the centre frame-clamp

Seems a bit of a strange way of parking - you shouldn't lower the seat post in that situation - I won't reach the floor anyway with the rear wheel not fully folded, so it makes no sense.

Anyway - there is a small circular dent on the titaneum rear triangle now but i am wondering if this was always there

My two Bromptons with ti-rear triangles both do have this dent, so I'd assume it is like that from factory. Never paid attention to that area before, so cannot be sure. But as I never park my bikes the way you describe and it is on both bikes I'd assume they came like that.

 

[snazpizaz]

thanks - just ot be sure - anyone else able to verify berlinonaut ? re also able to see a circular dent on rear inside of rear traingle ? I wonder why they would put a circular dent there ?
cheers again
sp

 

[berlinonaut]

On the steel rear frames there used to be a small hole on the opposite side of the same stay. It was needed during brazing to let heat pass out. Unfortunately, the open hole also let water, dirt etc. pass in and this may be the reason why elder Brompton rear frames rusted through sometimes. It is no longer there since ~2008/2009. I assume they close it now after brazing is done but don't know.
The ti rear frames are welded rather than brazed and I could imagine that the "dent" may have a similar background as the hole on the steel rear frames, just handled slightly differently. If it's from factory (as I assume) it will possibly have something to do with production needs and practices.

 

[brommieinkorea]

My superlight has those dents too. The factory crimps the tube to slightly ovalize it as a very tight fit is required to weld, especially titanium.