While riding in a slow moving traffic should I keep on switching to neutral when I stop the bike or should I keep the bike in 1st or 2nd gear holding the clutch?
Does changing gears frequently cause more wear and tear to the engine or holding in the clutch for long periods of time?
I would argue that wear and tear on the clutch is a secondary consideration.
There are too many idiots not paying attention on the road, and it's faster to pull away in first, than from neutral. That half second can be the difference between being hit or not.
as to the wear issue, @Mark answers that well.
I suppose it depends on a wet or dry clutch. A wet clutch doesn't have a thrust bearing and so you cannot "ride it". A dry clutch has a thrust bearing so the diaphragm on the clutch is pressing on it while it spins at engine speeds. There's no way of lubricating the bearings in the bearing case in the dry clutch, so there life is reduced every time the clutch is used.
What are the differences between a wet motorcycle clutch and a dry motorcycle clutch?
Your throwout bearing in your clutch is at risk of excessive wear
In the diagram below, your throwout bearing is number 17.
When you have your clutch pulled in all the time that flat bearing is where all of the spring tension from your pressure plate is centered upon. These bearing are relatively fragile and the reason why mechanics tell people not to 'ride the clutch' in a car.
If your driving in very slow moving traffic and can coast a bit from time to time then I recommend you do so. Of course, keep in mind your personal safety when doing this and that traffic is sub 15mph, IMO.
Notice how small the bearing is in the diagram and the amount of force being applied to it by the multiple clutch pressure plate springs. Too much extended use of the throwout bearing will lead to an earlier than normal failure. The pressure plate springs are labeled number 15 in the diagram and there are actually 5 of them.
The good news is, they are very cheap and very simple to replace.
I'll put my bike in neutral sometimes at stoplights, but I wait until one or two cars have stopped behind me so it's not as likely as I'll need to move suddenly to avoid being rear ended.
I haven't worked on many motorcycle clutches except the one in my old Norton Commando, but I don't think they usually have a thrust bearing. There's a bearing between the inner and outer basket that lets them spin independently of one another if the clutch isn't engaged. Also, most bikes use coil springs to press the clutch plates together, not a diaphragm.
