To ride the roads in my area, I use an old full rigid MTB. This bike provides the L-bend bar ends and low gearing I need for the hills here.

For years, I used the knobbies that came with the bike. They were probably as aggressive a tread pattern as one could get back in 1994. These knobbies were getting long in the tooth, so I replaced them with some semi-slick tires. They're a 1.9" width, with a road tire like slick center, and knobs on the sides. The hope was that they'd be more efficient for the 99% of the time I'm on pavement, while still OK for off road short cuts.

Yesterday was my first time with the semi-slicks riding in the generally down hill direction on a certain paved path. I found the lack of traction scary! One short very steep uphill was especially scary. With the knobbies, I'd lost traction there several times, but was never afraid of falling over. Now with the semi-slicks, I was afraid they would slip out sideways! Even on the long downhill, the new tires were less than confidence inspiring.

It looks like I have to go back to knobbies for road use. Is anyone else intentionally doing that?

I was going to build up another set of wheels for this bike anyway. I already have some NOS Shimano XT hubs. I'll put the knobbies on those, and keep the semi-slick clad wheels for commute use.