waanfiride

So, recently... when I'm climbing hills (for the most part) my bikes rear derailleur shifts on it's own. I've got sora, so I'm guessing it's just the ****ty-ness that is sora- but I thought I'd look into it. I'm a total bike maintenance noob... so I didn't want to mess with it too much before I knew what I was doing. I found a few sites on how to tweak derailleurs but I don't even know what the problem is to try to fix. Or am I just too fat and I'm crushing my bike with every pedal?

DXchulo

https://parktool.com/repair/readhowto.asp?id=64

Your rear derailluer probably needs to be adjusted. Your chain and/or cassette might be worn, as well.

Apus^2

Probably the cable has stretched a bit. A few turns of the adjusting barrel should fix it. Don't mess with the limit screws (yet) until you try the adjusting barrel.

https://www.sheldonbrown.com/derailer-adjustment.html
(see Indexing Adjustment)

Nothing wrong with sora.

rollin

Guess again.

bismillah

front derailleur out of alignment

BarracksSi

If adjusting the RD doesn't help at all (and I'm talking about doing it thoroughly and carefully, especially if you haven't done it before), two more options could be a slightly bent RD hanger and grime in the cable guide under the bottom bracket.

A bent RD hanger stymied me until I got it straightened out.

A sticky cable guide can tug gently at the derailleur cable when you're really pushing on the frame, sometimes enough to move the derailleur itself.

I'll bet it's not the fault of Sora, though.

roadiejorge 

maybe it's haunted....

waanfiride

I know, it was just a joke. I actually like my sora set up, affordable and works better than anything I've used before (granted I haven't used anything else on road bikes except for down tube shifters)

jrobe

It is an excellent time to learn how to adjust the RD. This one should take about half a turn of the barrel adjuster.

This isn't a bad tutorial. https://bicycletutor.com/adjust-rear-derailleur/

The Park Tool web site manuals are also excellent.

mwchandler21

Grimlins

dorkypants

Depending on what vintage your Sora shifters are and how old the shift cable, you might also check the head-end of the cable inside the shifter for fraying. Older Shimano shifters (pre-2009?) had a tendency to break the cable inside the shifter because of the extreme bends it was subject to; sometimes the broken bits jam inside, requiring a costly replacement of the whole lever assembly. The symptoms are auto-shifting or sloppy shifting that can't cured by cable-tension or derailleur adjustments.

A few dollars' worth of cable, preventively replaced, is worth saving hundreds of dollars for a new lever.

merlinextraligh

It likely is just RD adjustment.

However, if the frame is flexy, its not a big trick for a bigger rider to make the rear ghost shift, particularly hammering out of the saddle.

And poor RD adjustment would exacerbate that tendency.

Voodoo76

I didn't know Toyota was making bikes now.

yuanja

Cable tension.

deep_sky

While I will be the first to agree that Sora is complete crap, it does sound like you need some adjustment(s) made to correct the problem. If you don't feel comfortable attempting to do it yourself via reading tutorials on the internet, take it your LBS and explain the situation, I am sure they will be able to help you.

JimF22003

check for chain stretch too.

KiddSisko

Sora is not complete crap. And that's final.

rollin

I won;t have Sora disparaged!

As suggested by BarrackSi above, if you can't get the rd is adjusted correctly then worth having the alignment of the hanger checked over.

So to sum up the advice so far:

- Adjust your rd;
- replace your cassette and chain;
- adjust your fd;
- change the cables;
- adjust the rd hanger;
- call an exorcist;
- kill the Gremlns;
- re-tension your cables;
- buy a stiffer frame
and don't dis Sora.

Might be easier to buy a new bike

bruce19

My gf's Fuji Team Sport had the same problem. It's fitted with Ultegra. We tried all the fixes recommended here and they didn't work. Turns out it was the shift/brake lever which is not fixable and had to be replaced. (Not fixable according to the bike shop. They may have meant that it's so difficult/time consuming that it's not worth it. Not sure.) I do know it solved the problem.

rangerdavid

^^this^^

only about a 30 minute fix at your lbs.

deep_sky

Sorry, but it is. IF you haven't used a higher grade groupset maybe I can see why some would consider it adequate. Once, you have, you realize just how bush league the lower end groupsets are.

mobike_moexcite

I think it's cool that some people have bikes that shift on their own. Some people are just lucky like that...

But seriously take it into an LBS it's usually quick and not too expensive.

noise boy

For new riders, Sora and Tiagra work flawlessly. I have Sora shifters and tiagra derailleurs on my bike, and everytime I push the lever, it shifts, never been a problem. All you get as you go up the groupsets is slightly lighter components, and better materials, and possibly a slightly better shifting action/ergonomics. Case in point, my 17 year old mountain bike has the Altus A10 group on it and 17 years and a billion abuses later it still shifts every time I push the lever.

KiddSisko

I rode with Sora for a year flawlessly. Now using Sram Rival with issues. Get over your snobbery of pricey gear.

tntyz

Oil your chain.