I know it's a daft question as it depends on many factors but how long is too long that handling is effected, i'm new to this road game and all my mybs have 50mm stems.

The thing is i bought my first road bike and it has a 90mm stem on which is a bit too short, i think 100mm would be ok but incase i need longer when do things start getting twitchy, it's a medium frame btw.

ta

100-130mm, depending on all sorts of geometric factors. Could be shorter or longer too.

thanks i may go for a 110 then as the saddle is quite far back on the rails too so i can play with that

Oft quoted rule of thumb – sit on the bike and put your hands on the hoods in a natural riding position. Look down. As a ballpark starting point, the handlebars should be in-line with the front hub. This is of course, just a rule of thumb and not good for everyone, but it's a good starting point.

Mine came with a 100mm stem, I used the "oft quoted rule of thumb" above and fitted a Thomson 120mm stem and now it feels spot on.

: P

Most stock frames come with 100-110mm stems for a medium. You can alter the position of the bars and hood to make things feel longer, rotate them forwards slightly.

You do have the stem dropping don't you? Most stock frames seem to come with them upside down 😉 so they rise. It makes a huge difference to the reach and IME a noticeable difference in riding position that affects speed.

thanks, i'll try the above and yes it dropping at the mo