Berthoud stainless fenders are measured to the outside. The metal is rolled to the inside to eliminate the sharp edge, make the fender stiffer, and increase the life of the fender before it finally cracks and needs to be replaced. This makes the inside width of the fender about 9mm narrower than the stated width. I would want at least 5mm clearance on each side of the fender when the fender wraps down around the sides of the tire. So, with the40mm and 50mm stainless berthoud fenders, you should always use a fender that is a minimum of about 18mm wider than the width of your tire,measured at the outside of the fender, depending on how much vertical clearance you have over the tire in your frame.
If I were setting up a bike with 32mm tires, I'd use the 50mm wide stainless fenders. They are typically about 42mm wide on the inside, giving you about 5mm clearance on each side of a tire measuring 32mm wide.
The 60mm wide fenders have a flatter profile than the 40mm and 50mm do, so they don't have to be so much wider than the tire. 10mm wider is plenty for the 60mm fenders.
Keep in mind that these fenders are not made to extremely tight tolerances. There's always a bit of slop in the dimensions. And they can be bent a bit to fit. Before you start bendoing them, be sure about your final result, because once you start bending them, you will not be able to return them.
...and just sit there in silence listening to you talk bikes.But jags, if you just sat there in silence, it wouldn't be any fun at all! Always better to have your input!
My way of thinking is, "I buy the best, and I expect it to survive my kind of service, whatever I want to do, wherever I want to go."<nods> Well said, Andre! I've always been irritated by people (some of them friends) who own Ferraris...and then don't use them as-intended. A couple years ago, I met (nearly collected 'round a blind corner; yikes!) a brand-new, temp-licensed Porsche Turbo (900-series) with AWD. I stopped and asked how he happened to be on that same very rough and remote mountain logging road. "Just out four-wheelin'" was the answer. YES! This man "got it".
Sorry, hadn't realised you were using 28" tyres...Me, neither!
Take note, however, that white Paselas were significantly wider than black Paselas on my rim. I was running a fairly narrow rim, and black Paselas measured just a shade over 25mm. White Paselas (which looked to be perfectly sized for the 40mm guards) measured a shade over 28mm.