Changing shifters
 

I am looking to buy (my first) racing bike. However, the one that I am interested in has down tube shifters. I want to try them out but if I don't get on with them in the long run how easy would it be to install handle mounted shifters? The spec is shimano 600 mechs and chainset and 105 shifters, is it possible to just put any shimano shifters on them?

Thanks in advance.

The easiest conversion would be stem shifters. You should be able to buy a clamp-on fitting that allows you to move the existing shifters to the handlebar stem.

Being as the bike as Shimano 600 components fitted, these are probably going to be at most 8 speed, getting handlebar shifters (STI's) is hard due to availability. Currently only Sora is available in 8 speed, but you may find the cost prohibitive. Stem shifters are a option, but you then have the problem of sourcing the clamp, new cables and any other parts you need to fit your stem.

Would look for a bike which already has handlebar shifters fitted, as this will be cheaper in the long run, for will you like them, how many bike do you see without them fitted?

There is also the option of barend shifters, again, not cheap, but cheaper than STI's, and you will need to get the bar rewrapped, which is hard if you have never done it before.

Thanks very much! I think I'll keep looking, I would only consider it if it was a cheap/quick/easy fix for my inexperience.

Downtube friction shifters were the norm for many years and quite satisfactory; try them you may like them. Instead of planning on replacing them before you try them out, why don't you see how you do with them first? Beside the cost, STI shifters bring with them the hassles of getting the indexing right and are intolerant of minor damage or mis-adjustment that the plain friction shifters will easily take in stride. Kind of like a manual shift auto, you may find that you are more attuned to your riding with the non-indexed shifters.

I've done a few conversions for old road bikes with downtube shifters to STI "brifters." The low-cost route is to go with 7-speed Sora ST-3300 if you can find them. Bikewagon still has a few of the right-hand 7speed indexed shifter, but you may have issues finding a left hand. I've had to go "mutt" and get an ST-2200 black (not matching the silver ST3300) left hand, and it works fine. But that will run around $80 for the set. New housing, shifter boss mount cable guides, and new freewheel or HG cassette and possibly an HG-compact Acera/STX freehub body will add another $60. If you have the older Shimano 600 (6200 series) you might need to upgrade RD, and possibly FD. That can cost you another $60 - $100 or so. So that's not going to be a cheap conversion. I've been lucky that I've usually had existing 105, 600EX, or 600 Ultegra Tricolour (6400series) RD and an FD that could at least shift 2 chain rings without issues.

Something to consider for a fairly nice vintage frame. Otherwise, there is something charming and retro to downtube shifters, expecially those using friction.