Help with setting up my gears perfectly
My LBS is generally quite good at most servicing jobs but getting the gears to work smoothly generally appears to be beyond them. I was having trouble shifting into the lowest gear on the largest chainring - the chain would kind of get 'stuck'. And in general the indexing wasn't very good as the chain was quite noisy. I have a 24-speed cycle (3 chainrings at the front and an 8-sprocket cassette at the rear).
I decided to tackle the job myself after watching many YouTube videos on the subject. I'm pleased to say that the gears shift much more smoothly now! The front derailleur was just about perfect anyway so I didn't have to adjust that.
It seemed to be mainly a cable tension issue on the rear so a bit of fiddling around with the cable tensioner got things working smoothly. I checked the limit screws too.
Now I can change smoothly on all 24 gears. I can also pedal backwards on 23 of those gears smoothly. On one gear (largest chainring at front and largest sprocket at rear) I cannot pedal backwards smoothly - the chain slips to the next one or two smaller sprockets if I do so.
I guess that I shouldn't really be using this gear anyway as the chain is crossed at an extreme angle, but I was wondering if it's possible to get every single gear working perfectly smoothly when pedalling forwards or backwards on a 24-speed cycle?
Is this something I should worry about or just leave? The gear itself engages fine and there's no noise when pedalling normally (forwards). It's just the pedalling backwards that causes the chain to skip and jump to a smaller sprocket on the cassette.
I decided to tackle the job myself after watching many YouTube videos on the subject. I'm pleased to say that the gears shift much more smoothly now! The front derailleur was just about perfect anyway so I didn't have to adjust that.
It seemed to be mainly a cable tension issue on the rear so a bit of fiddling around with the cable tensioner got things working smoothly. I checked the limit screws too.
Now I can change smoothly on all 24 gears. I can also pedal backwards on 23 of those gears smoothly. On one gear (largest chainring at front and largest sprocket at rear) I cannot pedal backwards smoothly - the chain slips to the next one or two smaller sprockets if I do so.
I guess that I shouldn't really be using this gear anyway as the chain is crossed at an extreme angle, but I was wondering if it's possible to get every single gear working perfectly smoothly when pedalling forwards or backwards on a 24-speed cycle?
Is this something I should worry about or just leave? The gear itself engages fine and there's no noise when pedalling normally (forwards). It's just the pedalling backwards that causes the chain to skip and jump to a smaller sprocket on the cassette.
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Comments
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Is this something I should worry about
No.
WTF you doing pedalling backwards, unless you have a retro-direct gearing or are an acrobatic cyclist, then there is no need to pedal backwards on a bike.0 -
LOL. Okay, cheers. It's just that it's convenient to do so when oiling the chain - i.e. spin it backwards - saves me having to lift up the rear wheel.
Also at traffic lights if I want to get the pedal to the right position to move, I have to pedal back a bit, unless there's a technique I'm not aware of? I worry about the chain slipping down a sprocket or two.0 -
Now I can change smoothly on all 24 gears. I can also pedal backwards on 23 of those gears smoothly. On one gear (largest chainring at front and largest sprocket at rear) I cannot pedal backwards smoothly - the chain slips to the next one or two smaller sprockets if I do so.
Worn casette0 -
Now I can change smoothly on all 24 gears. I can also pedal backwards on 23 of those gears smoothly. On one gear (largest chainring at front and largest sprocket at rear) I cannot pedal backwards smoothly - the chain slips to the next one or two smaller sprockets if I do so.
Worn casette
More likely not the reason, it is a triple chainset and chain line is quite diagonal when in that particular gear.
As the guy said above, pedalling backwards behavour is not worth worrying about anyway.0 -
The chain and cassette were replaced a few weeks ago during a service at my LBS so I'm hoping nothing is worn out yet - I've only ridden about 30KM since the service.0
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The chain and cassette were replaced a few weeks ago during a service at my LBS so I'm hoping nothing is worn out yet - I've only ridden about 30KM since the service.
I would re-iterate the comments about pedalling backwards - if you want to adjust the pedal position at lights/ junctions, just lift the rear wheel slightly and pull/push the desired pedal to the position you want.
Couple of things about your problems with the big/big gear combination. One possibility is that your chain might be a tad too short. In big/big that would pull the derailleur cage into a near horizontal position causing the upper jockey wheel to get too close to the large sprocket on the cassette. When that happens the chain will not run smoothly and although you can pedal it forward, it might be reluctant to move backwards.
If your chain is the correct length, it could also be that the B-tension screw needs adjusting to keep the upper jockey wheel at the right distance from the cassette sprockets to prevent contact0 -
^ Ah! I was wondering what that other screw (B-tension screw) was for. Just looked it up on YouTube and it makes sense now. I'll check it over the weekend.
As I understand it, the B-tension screw should be used to correctly space the jockey wheel from the largest sprocket on the cassette. Some of the videos suggest a 2-3mm gap (gap between plastic teeth on jockey wheel and metal teeth on largest sprocket). Does that sound about right?
The chain was changed by my LBS and I would hope they replaced it with the correct size of chain.
I did a couple of short test rides and all 24 gears are operating smoothly pedalling forwards at the moment, but I am going to play with the B-tension screw now you've explained what it does.0 -
All sorted now. I did the rear mech alignment and gear indexing from scratch yesterday. I basically wrote down the steps based on several YouTube videos as follows (bike was mounted on a workstand):
1. Chain in smallest cog on cassette and middle ring on front (I read it doesn't matter which front chainring it's on so I chose the middle one);
2. Barrel adjuster all the way in clockwise and then out by one turn;
3. Adjust high limit screw until jockey wheels are directly under smallest cog but just very slightly outboard;
4. Loosen cable anchor, pull cable tight and re-tighten cable anchor;
5. Chain to one of the middle cogs and use barrel adjuster to align jockey wheels to be directly underneath cog. Cycle through all gears to check for smooth changes;
6. Chain on largest rear cog - adjust low limit screw to ensure jockey wheels are directly under the cog and just very slightly inboard (towards the wheel). Cycle up and down all gears to check for smooth changes;
7. Adjust B-tension screw with chain on largest cog to reduce the distance of the upper jockey wheel to the largest cog - this was a bit of trial an error as I rotated the pedals by hand and 'felt' and listened to smooth gear changes.
I hope that's the right procedure! It feels right out on the road.0
