Good Fellow

i am so close to checking "bike overhaul" off my list. but the last few steps are causing me a lot of frustration.

just some background information before i start: the bike is an old Mongoose mountain bike that has hardly been rode and was sitting in a shed for 6 years. i replaced the free wheel with a 14-34T 7-speed Shimano Mega-Range. the rear derailleur i have is a Shimano Tourney Megarange, so it should be capatable. i replaced the chain but didn't remove any links because i was unsure of the length after measuring it and figured it was better to have it to long rather then to short. also, the adjusting was done while the bike was upside down. i don't own a bike stand so i figured it was the best way to go about it.

i replaced my shifter cables and their housing and cleaned my derailleur, so i decided it was time to adjust them. but i cant quite pin the source of issues my bike is showing.

When i first attempted to adjust the rear derailleur, the chain made an awful lot of noise when it was in the lowest gear and the cage was vibrating (it was in low on both derailleurs, i was not crossing the chain). so i took the chain off and loosened the anchor bolt for the cable. then i screwed the barrel adjuster all the way in and shifted to the highest gear on the rear derailleur, then pulled the cable taunt, screwed the anchor bolt back in and put the chain back on.

i went through the adjustments again and the noise seems to have improved but it was having trouble shifting through the gears when i took the bike for a ride.

what i would like to know specifically is, should the barrel adjuster(s) be screwed in all the way before installing the cable (im wondering if cable tension was the cause of the vibrations)?is it better to install a chain using the pin rather then a master-link if it ensures more precise measurement? and how exactly do you use the barrel adjusters to fine tune shifting?

im going to try adjusting it again tomorrow and see what happens. sorry for the lengthy detail, but thanks for any help guys!

Airburst

Regarding the master link, I'd suggest you use one simply so it's easier to take the chain off for cleaning. As for chain length, as long as you have sufficient slack in the chain with it on the largest chainring and largest rear sprocket (you may never deliberately use that combination, but if you shift into it by accident and the chain's not long enough, you'll break something) that's fine, although you may have some slack if you use the small-small combination (which you shouldn't use either on account of cross-chaining).

As for adjustment, read the Park Tools article on the subject, they explain it very well. https://www.parktool.com/blog/repair-...nts-derailleur

dsbrantjr

"the chain made an awful lot of noise when it was in the lowest gear and the cage was vibrating"

It sounds like your "B" screw adjustment is allowing the derailleur cage to swing up too high, letting the chain hit itself; you don't mention adjusting it. Follow the Park Tool procedure referenced above, from the beginning and do not skip any steps. If you cannot complete a step properly, STOP and figure out why before you go farther.

+1 on using the master link instead of the silly Shimano joining pins.

Mose

+1 on all that. And if you follow the Park procedure very carefully and it still won't shift correctly, you may have a bent derailleur hanger. A good shop will have a tool that can align it, will take about five minutes. Also worth checking as it takes no time, try to wiggle the cogs with your finger; there shouldn't be any lateral movement. If you don't torque the cassette nut tight enough, it can loosen on its own and the cassette will loosen and cause shifting issues as well.

Good Fellow

it shifts great for the most part, but then, i haven't adjusted the front derailleur yet.

the only issue though, is there is no B-screw on my rear derailleur. i guess Shimano Tourney's don't have one. but the lowest back gear works pretty well assuming i stay in the lowest front gear.

i'll work on the front derailleur when i have the right tools to reach the adjustment screws. then the breaks are after that.

im so close to making this bike commute worthy, thanks so much for your help guys.

Airburst

If it has breaks, I'd avoid riding it. What's broken?

As for the lack of a B-screw, not all derailleurs have them, some cheaper stuff does without, but it doesn't sound like your problem would be solved by adjusting one anyway.

alecw35

I think they meant the Brakes are after that.

Airburst

I am aware of that, it was an attempt to point it out without just sounding like a spelling and grammar Nazi.

Good Fellow

i meant brakes. i have no idea why i keep spelling it b.r.e.a.k.s. , I've been trying to get out of the habit.

and thanks for letting me know. as far as i'm concerned, i shouldn't be in the low gear in the back without being in the low gear in front anyways, so it should work just fine.