robknowsnothing

hi everyone i am new to this forum so please bear with me ,

i am looking for some advice please on a couple of issues the 1st one is i recently bought a used bike with a few issues thinking i could fix them easy, well i did manage to complete around 99% but i am struggling with the rear derailleur. when i bought the bike the chain had snapped and derailleur ripped out of the hanger so i replaced the chain and new hanger fitted a new sram x4 derailleur (all i could afford) and new cables ect but no matter what i do i am missing gears its either 7and 8 are missing and 1st and 2nd depending on witch way i tighten the cable the shifter has no barrel adjuster neither has the derailleur am i correct in thinking at least one should have a barrel adjuster ? if i pull the cable by hand i get all the gears fine but just not with the shifter high and low screws are done also the shifter is original to the bike as is the rear wheel and cassette so left thinking maybe the derailleur is the wrong one . i was told it would be fine by the man in halfords as it was 8 speed and so is the bike ..

2nd issue is another bike with bent derailleur it is only a kids 6 speed bike but i can not seem to find a 6 speed derailleur anywhere all saying 7/8 speed will this work ?

i have probably went the long way around explaining this but i am a complete idiot sometimes with only very minor bike knowlage

thanks in advance for any help or advice you can give

JohnDThompson 

Did you check the new hanger's alignment before you mounted the derailleur? If not, go back and do that.

At least one barrel adjuster (either at the derailleur or at the shifter) will make shifting adjustment easier.

If it's friction shifting (non-indexed), pretty much any derailleur will work. With indexed shifting, the derailleur must match the shifter's cable pull.

jgwilliams

Just because it's an eight speed derailleur it doesn't mean that any eight speed derailleur will do. SRAM and Shimano use different pull ratios - that is the amount of cable they pull on each click - so if you have a Shimano shifter with an SRAM derailleur it probably isn't going to work. I think you need to give us a few more specifics, but you also can't assume that an eight-speed cassette designed for Shimano will work with a SRAM shifter and derailleur, although I'd guess they probably will. Others on this forum will probably be able to answer that. Assuming that they will then you're cheapest option is probably to get a matching SRAM shifter and a new gear cable.

I'd suggest you tell us what the bent derailleur was that you've just taken off, which will help us be a bit more specific with our answers.

With regard to the 6-speed bike; can you tell us what the bent derailleur is. That will help us with recommending a replacement for you.

By the way, you aren't a complete idiot, you just lack some knowledge and you're going the right way about acquiring it. As the saying goes: 'Experience is what you get just after you needed it.' Keep persevering and eventually you'll be an expert.

robknowsnothing

thanks for reply sorry i should have mentioned in my post the derailleur from the 1st one had no make on i could find badly looked after but the shifters are shimano and the so that now makes more sense to me also the 2nd bike is just a cheap kids bike with a shimano tourney tz 6 speed is all it has on it

robknowsnothing

oh i have no idea its just a cheap thing from smyths toys my sons bike nothing fancy if that makes any difference

joeruge

When I read this I immediately thought 'limit screws.' I don't know about the compatibility of the shifters and the rear derailleur, but I'd check your limit screws before chucking the shifters or derailleur because they are different brands.

There are two small screws on the derailleur that limit the range the derailleur can move. One limits the how far out the derailleur can swing so the chain doesn't fall off the smallest cog. The other limits how far in the derailleur can swing so it doesn't throw the chain into the spokes.

There are lots of videos out there that's explains how to do this, so I won't go into details here. But along with the derailleur alignment, this should get you most of the way there.

jgwilliams

Now I come to think about it, Shimano and SRAM cassettes have always been interchangeable, so if you get a shifter suitable for your X-4 derailleur then I would think it's pretty certain to work. For the kid's bike, Tourney now starts at 7-speed. However, if the pull ration is the same as for the 6-speed, which seems likely, then it will work fine. There is a vast wealth of knowledge on these forums so I'm certain you'll have the answer to that question soon. Alternatively you could scour Ebay for a used Tourney 6-speed.

I see you're in the UK. Whereabouts? If you're anywhere near me (Epsom Downs) I'd be happy to help.