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Evening all,
I have built a number of bikes, I can do everything apart from setting up gears. Doesn’t matter what I try I just can’t get them to work properly.
Bleeding brakes - no problem
Rebuilding calipers - no problem
Building wheels - can do with plenty time and patience
Service forks - no problem.. you get the idea
Setting up gears - not a Hope in hell.
Where am I going wrong? How tight should the cable be to start with? Where should the screws be to start? Clutch on or off on mech?
And if anybody in Dundee area can give me a master class tomorrow I would be delighted and happy to pay with beer/cakes or a donation to a charity of your choice.
Bike is all built and ready to go bar the gears.
I put the mech on the smallest sprocket, the shifter on the matching setting, fit the cable and pull it hand tight.
That’s hand tight, not swinging on it like a chimp or using any kind of mechanical tool, and tighten the pinch bolt.
Then shift the shifter one gear, pedal the bike and adjust the barrel adjuster until it shifts.
At this point it should be basically correctly adjusted, or very close to it.
Obviously, the end points would be done before this.
Clutch off
Set the limit screws first though. Can get messy/expensive if you jump straight into setting the cable tension.
Fit mech (no chain fitted)
Adjust limit screws
Thread cable
Make sure shifter in lowest gear position
A slight push of the derailleur to add a tiny bit of tension and nip the pinch bolt
Check the travel
Fit the chain
If this doesn't work I'd check hanger alignment. And if it still doesn't work then I'd check the cable outers and ferrules are seated.
Can you get to Perth tomorrow with the bike?
It's Axs time!
Pretty much as @martymac says:
Measure and shorten chain if necessary and then fit.
mech and shifter to smallest sprocket - the mech wants to do this anyway
Set high limit screw
Push mech by hand to biggest sprocket and set low limit screw.
Let the mech return to smallest sprocket
Wind barrel adjuster fully in then out two full turns
fit cable so it's hand tight regarding tension, tighten pinch bolt
Use the shifter to move the mech one gear. If it doesn't make it to the gear turn the barrel adjuster anti-clockwise until it does, if it goes too far then loosen the tension by winding the barrel adjuster clockwise a little.
Once you've got the change between those two gears sorted go up and down the block ensuring that each click of the shifter makes just one change of gear.
Finally sort the b-screw.
All the above but....it does all depend on the gear hanger being properly aligned. If it's out it doesn't matter how well the mech and shifter is adjusted it won't work properly
Thanks for the info so far guys, what do I set to limit screws to then?
what do I set to limit screws to then
Basically the guide jockey should be directly under the relevant cog. If the chain (and therefore guide jockey) are on the smallest cog then adjust the high limit screw until there's no undue noise, it shouldn't sound like the chain is wanting to jump off the cog. Check that you can still change down and back up to the gear. Do similar for the low limit.
MECH HANGER ALIGNMENT FIRST!
Mech hanger is all fine.
OK, OK.
Get yourself a mech hanger alignment tool, sort the hanger alignment then do all the above.
The Park Tools DAG, mech hanger alignment tool, makes the perfect tool for beating some sense into people WHO TRY TO SET UP GEARS WITHOUT FIRST ALIGNING THE ****ING MECH HANGER!
It being new, looking OK to my eye, I’ve never had a problem before, does not make the mech hanger straight.
Your inability to adjust gears may be explained if you have been in contact with someone with the single speed virus.
Or God is trying to guide you into the true path.
🙂
Limit screws first. Onto the smallest sprocket. Tighten cable with adjuster wound full in. Change down one sprocket and adjust tension until shift is complete. Up onto largest sprocket and repeat changing up.
It’s pretty easy to do it by eye without a chain too.
Different wheels may have different offsets for the sprockets. You can adjust shifting on the fly with the. Able adjusters, butvthe limit screws may not be set correctly.
Thanks for all the input folks. Went back out to the garage as it was bothering me and managed to adjust it all pretty much spot on. Maybe a final tweak tomorrow when I’m less tired and I’ll be good to go ride. I think I had a mental block about gears but when you know what’s what and take your time it’s really not that hard.
thanks again.
I found these Park Tools 'How To' videos really helpful when I was struggling with indexing my gears:
How to Align a Derailleur Hanger
At this point can I rejoice in the demise of the front mech?
**** off and please don't let someone invent it again.
The methods above are all fine, and the mech hanger point very valid, but also RTFM.
Different mechs have different ways to get the correct amount of chain, and different ideal settings for B tension and cable tension. You can get it working OK without these details, but you know it will work right doing it per the manual.