General Cycling Discussion - Sora gears

My new acquisition, a used Mercurgo road bike (no, I've never heard of it either..) has Shimano Sora gears. They seem to want to shift up a couple of gears occassionally for no reason. I intend to have the bike on the bench tomorrow to check them over. As I'd never used brake levers with gear levers built in, I'd appreciate any advice in setting them up, and also changing gear. There seems to be 1,2 or 3 clicks as I change down depending on how far I move the lever. I'm not 100% sure on this as I've only ridden about 15 miles this afternoon and there wasn't that much consistency - most of the time they worked great. There are 8 cogs, 11 to 28 and two chainrings, 39 to 52. The brake lever changes down and a small lever changes up. The advert said Shimano Sora Flight Deck. Hope all this means something to some of you guys ?
Regards
Albert

Check the Park Tool website.

I suspect you have a little cable stretch. If that's the case, if you turn the barrel adjuster adjacent to the reqr derailleur 1/4 turn it'll fix your shifting.

Flight Deck means the set is compatible with Shimano's multi-function computer. As Retro says, sounds like you just have a little adjustment problem.
Most of these are set up to move the rear DR one cog at a time with a small movement, or three cogs at a time with a full sweep of the lever.
That's for downshifts only; upshifts are one at a time.

A used bike and unless it has been maintained well- there will be things to adjust- lubricate and replace. The gear changing sounds like cable stretch but could also involve new cables. Any Rust on the cables inside the outers?- then replace them. Clean any parts that appear dirty and lubricate them if required. AND the wheels. Are they true? are the spokes tensioned right? and on wheels- do the brakes work?

Spin the wheels and see if the rims wobble. A fraction out of true is OK but if the rim visibly wobbles get them trued. Ping the spokes and see if any make a lower pitch than the others. If they do- get the wheels detensioned and retensioned and trued.

You may be lucky and just have adjustment problems on an older bike- but check it out before you ride many miles.

First off look for sticky chain links that don't pivot well.

I had about 3000 miles on a Sora RD when I had to take it apart and relube the top jockey pulley. It was squeaking when I was climbing or otherwise hammering and had a similar tendency to ghost shift to the next larger cog when I was doing the same thing. That and relubing that last section of RD cable fixed the problem.

As ever, thanks for the info. Before I took it on the road I did indeed dismantle, clean and adjust gears, brakes and hubs, etc. I didn't have much time this evening to check the gears, but I did have a go. I had the bike upside down on my Black and Decker workmate and adjusted the cable to a little more tension. I suspected this but have only experience of normal/older (!) gears and was grateful for the replies. The gears worked OK, but they always do when you're not riding the bike ! I did notice that the amount I was moving the lever was more critical than I had realised - I had to make a more positive move for the gear to move just one cog. Perhaps I had just been too gentle with the controls - there's always a first time !
Must try it out tomorrow
Albert