I currently have a Triban 500SE which is fitted with microshift shifters, front dérailleur and rear dérailleur. It has a Claris triple crankset and a suntour rear cassette.

What I am looking to do is to change the crankset to a double. The whole reason behind this is chain rub. It's one of the most annoying/embarrassing noises to put up with when riding, which I thought I got rid of when I moved from kids mountain bikes to a road bike.

Anyway, I've looked at a Claris double chain set as it's relatively cheap, with the shimano bottom bracket.

Do I need to change the front dérailleur? It can I use a triple? If so what needs adjusting and how to stop from damaging my shifter or pinging the chain off.

Has anyone any experience with this? Is it viable and useable, or is there anything I could change to get the triple to work better without the chain rub? (Obviously the gears have been set up as best as I can do them)

Thanks in advance.

Not sure that going to a double crank will eliminate chain rub. Unless you ride in the small rings a lot. And if you do the loosing that gear range will be a problem too. But you'll find out on your own.

As long as the new rings are close to the same sizes that the triple had (mid and large) you'll be fine. There is a chance that the ft der cage inner plate's bottom might contact the double's small ring teeth tops when in the large... There's a chance you might bot find that the triple shifter throws the ft der in a range that a double wants. (Therefore increasing the chance of rub). Switching the shifter to a double would help prevent this. Simple ft der adjusting will be needed, range limits redone and maybe position on the frame with cable tension adjustments.

The best way to eliminate rub is to both have the system well adjusted and then NOT USE the combos that rub. Shimano long ago published a little guide for which combos to not use. As you suspect it said to avoid those combos that did rub badly but that some rub wasn't wrong. Andy.

You don't even need to swap out the crank as you can simply lock out the inner chain ring. Agree with post no. 2; the right solution is to adjust the FD properly.

I'm going to jump on the "front derailleur isn't adjusted right" bandwagon.

My recommendation is to start completely over. I could teach a chimpanzee to adjust a rear derailleur but fronts are much trickier. I think that the heart of the issue is that each front derailleur tweak affects subsequent adjustments so, once one adjustment isn't perfect, there is a tendency for making subsequent mis-adjustments.

I'd start by completely disconnecting the shift cable. I recommend the step-by-step instructions on the Park Tool site. Pay particular attention to the position of the derailleur on the seat tube, the very first adjustment of them all, because that's where I've found the problem usually lies.

Good luck.

Where is the chain rubbing? If it's on the front derailleur, the suggestions above are good. If the chain is rubbing on the middle chainring when it's on the small ring in front and small cogs in back, you may need to learn to avoid those particular gears.

FWIW,

Proper Chain line for a Double centers between the 2 chain rings , the Chain-line for a triple puts the middle ring On the chain centerline.

which is a line to the center of the rear cluster (3 of 5, 4 of 7, 5 of 9, 6 of 11)

I actually had a go at adjusting the FD and to be honest it just left me baffled.

I did exactly as recommended (bottom ring, lowest gear, release cable, adjust height and alignment, reconnect cable, adjust low limit, adjust high limit) but there lies no room to adjust for the centre ring. It basically makes a few gears redundant.

I've even toyed with the idea of swapping out the groupset, bar the brakes. But that just seems a cost that I don't really want to endure at the moment. I'd much rather get on the bloody bike and ride it.

1. Most shifters have a trim function to fix chain rub on front derailleurs.

2. Chain rub on the big ring is much more likely with a 50-34 compact double because of the larger difference between chain rings and chain angle greater due to the more inboard location of the 34 ring

Perhaps.

Use the shifter trim function or switch to Shimano if Microsoft lacks it.

This is probably going to sound daft, but the barrel adjuster is attached to the shifter? Where the cable runs out. Reason I ask is that I'm not at all familiar with 'sti' type shifters. I don't want to adjust that in case it's for the brakes.

You should be able to tell if the cable in the barrel adjuster goes to the brakes or the derailleur.
At this point, it may be reasonable to take it to a shop for adjustment. Likely to be cheaper than changing out crankset. They should at least be able to tell you if the rub is avoidable.
Your comment about redundant gearing is correct. I have a triple, I use the smallest chainring only on steep climbs, and only on the largest 3 (or sometimes 4 if I hit a short false flat) rear cogs. I find the middle ring useful for moderate climbs, or for variable terrain, but there is quite a bit of overlap with the large ring.

Try adjusting your low limit before attaching the cable. Height and angle, then low limit, attach cable, then check tension and make sure it's enough to smoothly pull the chain up to the higher gears. Adjust high limit after that, then make sure the tension is perfect to pull the chain around where it needs to go, then double-check everything, and then do it again. If this is about doing it yourself then adjusting a triple is a great way to cut your teeth and make sure you won't run into similar issues if you change parts. You could try replacing the cable depending on how old it is, just in case. Otherwise, see what your LBS can do.