Originally Posted by
jonc123
Are folding tires compatibility with most modern rims? Mine have the hooks on the inside (Alex DH19 558X18). Also, looking at Sheldon Brown's chart on tire widths & rims it looks like I'm about at the max width of tire (42mm) for this rim. Sound about right?
Yes, folding beads are compatible with modern rims.
Originally Posted by
bikemig
Well you certainly want a rim with a hook; some older rims lack the hook which can be a problem with modern tires.
Insofar as the Sheldon Brown table you care talking about, the table is conservative. Not a problem if you fall within these recommendations but I know I have used working combinations outside of what is recommended here. If you get a tire up to pressure and it doesn't blow off the rim, you should be good.
If the bike has 27" rims from 1983, that's about the only rim that I've seen that doesn't isn't a hooked rim. Most every thing made since then has is a hooked rim. There may be some nonhooked rims on BSO from HelMart but I'm not even sure about that.
As to Sheldon Brown's chart, I'm beginning to question the validity of that chart in its entirety. On the large side of the chart, I run 55mm tires on 17mm rims on mountain bikes and have for many years. Granted these are lower pressure applications...around 45 psi...but I can pump them up to 60 or 70 psi and still not run any risk of blowing them off the rim. On the small side of the chart, he suggested a 40mm tire on a 23mm rim but
Velocity A23 are 23mm rims that are meant for 23mm tires. I have a set with 23mm tires on them and they work as advertised. I really think we should throw out that chart or broaden the range to the point of near meaninglessness.
Sorry to speak bicycle sacrilege but Sheldon Brown was wrong on that one.