The knobby is 1.95 wide, the slick is 1.4 wide. For city use,

which tire do i put in front?
what setup would be faster?
help with hand vibration?
overall bumpyness?

Slick in front would be less bumpy than the knobby in front and easier on the hands. Doubt much difference in speed as the knobby will slow you down a lot (5-10mph).
Steve

+1

Also if you lose any traction, its far better on the rear rather than the front.

There are several reasons I would, and do, run the slick as the rear tire.

The rear tire bears the most weight and creates the most drag. Putting a higher pressure slick in the rear will greatly boost your speed.

The front wheel is the critical wheel for steering traction and the the wider knobby will helpkeep steering smooth through bumps and potholes.

I find traction adequate with 2 knobs on road for the way I ride.

I wen't with the slick in back. Didn't test very long, but doesn't seem too bumpy in back.
Sheldon Brown's site suggests this will be the fastest setup. The big question mark for me was whether smaller smooth tire in front has less vibration than large knobby.

As far as traction goes, slicks have better traction on pavement.

I currently use a 1.5 Geax slick on front with a Ritchey 1.00 slick driving the rear. Its a tremendous speed difference over running 1 or both knobbies.

I rarely use that mt bike anymore for commuting. Now it only gets used on rainy days. Most of the time I ride my road bike and it sports 700 x 23 slicks. They reliably carry me over the 2 miles of gravel that I must cross on my daily commute.

I'd put the fatty on the rear to use the extra air to absorb shocks to my butt. If I was more concerned about my hands, I'd put it up front. If you are really worried about speed, go and buy another slick.

For city use I'd go with two slicks. Why do you need one knobby tire on the city streets?
In the winter I use knobby up front to crush through snow and once it gets really bad I switch to two.

--- Check out this thread from January 4th, 2005 entitled "Tires: Mix or Match?":
https://www.bikeforums.net/showthread...ight=mix+match

I will get another slick within a few weeks. Using one tire at a time to get each size right.

So far slick on back feels slightly faster (but not dramatically), but its comfortable.

I think a Performance brand slick is under $10 right now...

I'm up to 2 slicks now. Have a similar bike with 2 knobs that is setup most of the time as a grocery getter, but is also the wife's touring-by-designation bike.

Some of the results from the experiment:
There is a much bigger impact on speed going from knob to slick on back, than from adding the 2nd slick.
big knobby on front or back is noticeably more comfortable for bumbs, and a slight improvement on vibration. A $25 nimus 1.5 with kevlar thicker decorative-hybrid-rain-car-tire thread seems noticeably more comfortable than a $20 no-name 1.4 slick.

I don't really understand the traction arguments on road. The only time I've come close to losing traction was turning too quick too slow, and remedied by pedalling/accelerating out of it. Front wheel traction might come into play trying to go as fast as possible downhill on a twisty path, but that seems more like offroad scenario, and at least not typical city commuting riding style.

Fatter tires seem to handle great on roads, and knobbies appear to have perfectly adequate traction. Handling 1.95 knobbies seems better than 1.4/1.5 slicks, but only marginally.

Slick tires are best in all conditions, on all road. Note road, not trails, gravel others.

Had the same situation. I had one slick, one knobby for my MTB. I put the slick on front and didn't notice much improvement in speed, maybe 1 mph. However, when I put the slick on back, I got a 3-4 mph increase and much better handling and cornering.

Simple rule:
Loose surfaces - best traction offered by knobbies.
Hard surfaces - best traction offered by slicks.

slick in back, knobby up front. rear wheel has way more traction when under pedal force.

So tell me. Is this a scheme for making your bike less attractive to thieves?

Its about upgrading a MTB for commuting, and balancing speed, cost, comfort, and yeah, maximum dorkiness for thievability