Hi, the centre of the handlebars where it bulges to be clamped by the head stem is 22.2 in diameter. The bars are 360mm approx wide so want to find some bars around 400-420mm that will fit though the GB stem.

If I ream out the head stem to fit standard 25.4 diameter bars it seems a lot to ream it might weaken the stem

If i put wider bars on will that fatigue the stem through the extra leverage, this bike will be a commuter rather than going hard

Is there more options available with steel bars

having said all this I want to keep the GB stem - it's quite distinctive, I realise I could swap the stem for a better design cinelli or ttt which would solve the problem