Hi just wondering what your advice may be regarding seatpost length.

issue: having bought the Cube 17″ GTC pro SL 29er the 19 would of been too big i prefer a smaller frame that I can throw around a bit more; I find i have the seatpost up over the limit line by 5mm. Its a 400mm seat post so there’s 95mm left in the downtube.
The LBS said to keep it no higher than the limit line as this may cause issues with the frame…!…should i be looking for a longer tube?

Its actually the frame rather than the post you need to be looking at – the post needs to at least get below the bottom of the weld where the top tube and seat tube meet. The mark on the seat post is where that point would typically be on a completely normal frame, but these days you get all sorts of weird things happening at that intersection.

Longer seat posts are available too, mines either 420mm or 450mm, I forget which

If the frame does break, they’ll be able to tell from the witness marks on the seat tube that it was above minimum insertion. This would be used as a reason to refuse the warrantee so I’d say yes.

edit – Could you not just get used to a 1/2cm reduction in seat hight? It’s not a lot!

Bike mechanic years ago told me to lay the seatpost against the frame, and make sure the bottom of the seatpost goes past the bottom of the seatpost and top tube junction (i.e. the post goes past bottom of top tube), that should be the max height you can use 8)

Could you not just get used to a 1/2cm reduction in seat hight? It’s not a lot!

Or get a taller saddle, there’s about 2cm difference between my racey and comfy saddles.

A lot of frame manufacturers recommend at least 100mm of post in the frame.

I always make sure that I run at least an inch below the seat tube / top tube junction anyway.

Some frames have sleeves in the seat tube so no matter how much post is in the frame, it’s only the sleeve that’s supporting the post anyway. Put you finger down the seat tube to see if it’s sleeved .

If there is a sleeve, your post should at least be inserted to the same length.

I’d e-mail the manufacturer and ask them myself just to confirm.