mangled chain - what am I doing wrong?

sbullett

Re-posted from C+ - thanks for the 4 of you who posted there before the move...

Hi there

Got my first road bike (Giant SCR2.0) for 25 years a couple of weeks ago. Fantastic bike and have been scaring myself silly getting used to the speed and gears/brakes compared with my old MTB-commuter.

However I have managed to twist the chain already. I suspect the problem is my infamiliarity with these new fangled shifters on the brake levers - I'm hoping someone can tell me what I did wrong?

The bike is a triple and has Tiagra shifters. The scenario is trying to change up from lowest (smallest) front chain ring to the middle (so not travelling too fast in terms of MPH, but at a cadence of around 90-100). I haul the lever across towards the right and the front mech duly moves across towards the middle ring, but on about 3 occasions already the chain dives off the lowest ring towards the frame and gets jammed up between the chainring and the bottom bracket. First couple of times it happened I managed to extract it without any problem but last night it twisted quite badly and one of the links is bent

I managed to get back the car with the chain slipping like mad but need to get a new chain today.

So what's happening? Am I doing something wrong (not pushing the shifter firmly enough? pushing the little black lever before the main lever?) or is it a fault with the bike?

Any help for this roadie novice would be greatly appreciated!

Thanks

Simon

madmole

Sounds like the Low Stop has not been set properly.

With the chain off, click the front mech to all 3 cogs and check it sits immediately above the rings and when on the large one the cag is 2mm above the cog wen viewed from the side

If the derailer is inside the small cog adjust the L screw till its in alignment and use the H screw to do the same to the large cog. Use cable tension to sit the cage correctly aboive the middle cog first though

Make sure all derailler mounts, chainwheel bolts etc are firm. Lastly make sure is the correct chain. An 8, 9 and 10 speed chains are different widths and having the worng chain will allow movment thats not intended

Good luck

rafletcher

If the bike is only two weeks old take it back to where you bought it and explain the chain dropping issue.They should adjust the stops FOC - although if you've been riding MTB's for 25 yrs you may feel confident doing it yourself. On the other hand if you were confident you'd already have done it! So to the LBS it is, for adjustment.

Two sheds

You could also get a chain catcher device to stop this happening in future. These are banded onto the seat tube and prevent the chain falling off inboard.

Search for 'Deda Dog Fang' - they cost buttons and weigh next to nowt.