Chain Slip at front changing from large to small front chain wheel (with large cog at back)

Question

I have a Pinnacle Neon 3 Hybrid, Shimano Sora 9 speed cassette and 2 chainrings at the front.

The bike is 2 weeks old and I've cycled around 65 miles so far.

Chain ring has come off 3 times at the front 1st time was when on the big ring at front and I selected wrong direction on the chainwheel (ie moved it outward instead of inward to smaller chainring - think I was on smallest cog at back), so I put it down to possible user error.

Today, the chain came off inwards twice at the front when moving from the large front chain ring to the small one whilst in the large cog at the back.The chain went past the small chainring. I have read it isn't ideal to be changing like this but should it really be coming off like that?

My previous bike, also a Pinnacle Hybrid, had 3 chainrings and I never had 1 chain slip in 6 years.

I'll probably take it in to be checked but wondered if there's anything I can do to adjust and make it less likely before the 1st free service is due in a month.

There is chain rub when on the largest cog and smallest chainring. Is it worth adjusting the H screw on the front derailleur to prevent the chain flying off when moving inwards as above from large to small chainring, or is it more likely due to the fact I was going from large chainring to small chainring ("extreme gear") when in the smallest cog?

Thanks

Martin

Answer 1

I wouldn't expect to throw the chain inwards or outwards (at least on my 3x8 setup) if the limit screws are correct. This is true whatever sprocket I'm using and even if I push the lever the wrong way (it's not unknown when I'm tired especially if I've recently been riding another bike). That said you shouldn't be shifting like that as you acknowledge. The tolerances are likely to be tighter with a 9 speed chain but I would say there's no harm in a light tweak of the limit screws and tension, in fact after a few 10s of miles on new cables or after other significant changes I tend to find that some adjustment is needed as things bed in.

Answer 2

I have that problem with my road bike as well, Shimano sora STI shifter, claris derailleurs, 2x9 setup.

What I did :

1. make sure limit screw (L) adequately adjusted, i.e. just about to rub the chain when Small CR + Largest Cog. (so you are ok here)

2. shifting in sequential manner. e.g. 2-9 then 2-8, 2-7 ... 2-5 (or 2-4); at this point, shift to 1-5 (or 1-4) while pedalling lightly for smooth transition

The reason behind this, also demonstrated in two of your case is that:

1. from 2-9 to 1-9 for example, the tension on the chain is not enough, making the chain swing off freely.
2. from 2-1 to 1-1, the chain was crossed inward, together with chain tension, pulling the chain inward and off the small chainring.