Phil asked...
...could a low quality stem ever fatigue over time or break even?
Yes, but so could a new one, eventually! I have seen crummy-looking old stems soldier on and on while the odd new one can quickly develop cracks. And vice versa, of course.
Phil, so long as the stem appears sound on close visual inspection and it doesn't creak in use (which can be a sign of fatigue, loose bolts, or a poor match between stem and handlebar diameter), you should be fine. I'd be leery if it has signs of road rash or a damaged surface. however. You'll have an opportunity to inspect it when you swap the bolts over.
I was just wondering if there was much difference in quality between stems...
Well, yes there is. The cheap ones are produced by less expensive means, which usually means they are melt-forged. To make up for any loss in strength, they tend to be solid or have thicker walls, makingt hem heavier for a given size. The more expensive ones are cold-forged and result in an aligned grain structure for greater ultimate strength; thinner walls or hollow cross-sections allow them to weigh less. In ordinary use there's not much practical difference.
If you have the extra 15 quid, then sure. If you don't, then I think you'll be fine so long as you inspect it closely. You may wish to consider a Thorn Accessory T-bar for your handlebar bag, if you carry one. That'll take that much more weight off the stem as well.
Very best wishes for a safe, happy journey. We'd love any updates you care to offer; good thoughts will go with you!
Dan.
