Hello,

I’m not certain this is the proper board for this query so apologies if I’ve run aground.

I’m using some older parts on a new frame with a 1” threadless head tube. My only matching stem is a 3t mutant which has (I believe) a -10 degree rise.

I had my mechanic press the headset and leave the steerer long to accommodate an upright riding position required by my less than nubile body.

The steer is currently about 110mm above the headset. I was planning to keep the height and set the stem at the top.

My mechanic objected and mentioned with a negative rise and a 2-bolt faceplate could be unsafe if sitting on more than 40mm of spacers.

He thought such a stem wasn’t to be flipped and this would be unsafe.

He suggested a 120mm stem with a 17 degree rise would be perfectly safe at any height.

So, what gives? This doesn’t make any sense to me and I’ve never heard anything along these lines before. I can’t see a reason that shear force would vary significantly on a positive or negative stem or how flipping this stem would make it less strong.

Anyone have any insight or experience to share?

Finally, if anyone has experience using either North Roads style bars or perhaps Bosco’s I would be grateful to read your opinions!

thanks