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Only shifting 4 gears

Posted: Sun Jan 06, 2013 6:50 pm
by Kaffine
Greetings folks

I've been getting back into riding (road) over the last few months bought the new bike and heading out each day. I'm attempting to get mt old Giant ATX 840 back into shape for those quick rides to the shop and back maybe a track or two.

The drama I've encountered is that no matter how much I adjust the rear derailleur it will only shift 4 out of 8 gears, I've opened the limiters right out, adjusted the cable tension in and out but still only 4 gears,


What am I doing wrong.

I'm by far not a bike mechanic so the problem may be very obvious.

This only has to last a short while until I get a newer MTB.

Thanks in Advance
Craig

Re: Only shifting 4 gears

Posted: Sun Jan 06, 2013 7:24 pm
by kb
Top, middle or bottom? Most likely the cable is too tight or loose. Do you get the whole range of motion with the cable unclamped?

Re: Only shifting 4 gears

Posted: Sun Jan 06, 2013 8:09 pm
by Kaffine
kb wrote:Top, middle or bottom? Most likely the cable is too tight or loose. Do you get the whole range of motion with the cable unclamped?



I can adjust the derailleur so it uses the top 4 gears or middle or bottom just not all 8,

I've just realized the front derailleur only shifts through 2 gears not all three.

The bike hasn't been ridden for a while, I'll spend some time on it if needed just don't want to spend to many pennies (which will go towards the new bike), this will hopefully get me some experience on the mechanics of bikes in general.

Re: Only shifting 4 gears

Posted: Sun Jan 06, 2013 8:14 pm
by Mulger bill
Try unhooking the cables and see if you have the full range of movement. If you haven't used the bike for a while, corrosion might be an issue.

Re: Only shifting 4 gears

Posted: Sun Jan 06, 2013 9:24 pm
by Kaffine
Mulger bill wrote:Try unhooking the cables and see if you have the full range of movement. If you haven't used the bike for a while, corrosion might be an issue.



OK, Released cable from RD, Derailleur has full movement, I also set the end limits, with a slight tweak of the cable tension I'm almost getting 5 gears :shock:

Re: Only shifting 4 gears

Posted: Sun Jan 06, 2013 9:32 pm
by bychosis
Try some YouTube vids of how to set up the derailleurs. Also try holding the cable in your hand and clicking through the gears to see if the shifter will let the cable move properly. If the derailleur moves without the cable connected sounds like a problem from the other end, or maybe the cable is rusted/sticky somewhere in the middle.

Re: Only shifting 4 gears

Posted: Sun Jan 06, 2013 9:41 pm
by Kaffine
bychosis wrote:Try some YouTube vids of how to set up the derailleurs. Also try holding the cable in your hand and clicking through the gears to see if the shifter will let the cable move properly. If the derailleur moves without the cable connected sounds like a problem from the other end, or maybe the cable is rusted/sticky somewhere in the middle.



BAH You Tube, why do I bother when I've got you guys to help, manually pulling the cable and the derailleur runs through all the gears.

as you mentioned I'm lookin up the wrong end :oops:

Awesome work..

Any lever gurus here???

Well antique lever gurus :D

Re: Only shifting 4 gears

Posted: Mon Jan 07, 2013 12:01 pm
by Mulger bill
Simple, non scientific lever test (without knowing what sort of lever... :wink: )
Cable unhooked and shifter in 1st, hold the cable with some tension between your fingers and slowly click the shifter up to 8.
Do you get 7 smooth feeling clicks? Does the cable seem to pull the same amount each click?

Re: Only shifting 4 gears

Posted: Mon Jan 07, 2013 3:41 pm
by bychosis
Mulger bill wrote:Simple, non scientific lever test (without knowing what sort of lever... :wink: )
Cable unhooked and shifter in 1st, hold the cable with some tension between your fingers and slowly click the shifter up to 8.
Do you get 7 smooth feeling clicks? Does the cable seem to pull the same amount each click?


Kinda what I meant, but testing the derailleur by pulling the cable by hand was a good one too.

As for shifters, I have heard, but not by experience, that dissassembly of any trigger style shifters allows some magic to escape and they cannot be reassembled.

YouTube is a useful additional resource for those who learn visually, it's helped me where a wordy descriptions miss. Picture's worth 1000 words, video must be worth at least a million.

Re: Only shifting 4 gears

Posted: Mon Jan 07, 2013 6:32 pm
by Mulger bill
bychosis wrote:As for shifters, I have heard, but not by experience, that disassembly of any trigger style shifters allows some magic to escape and they cannot be reassembled.

Pretty much so for Shamino. Swiss watchmakers spend 6 months on the brifter assembly line as part of their apprenticeship :?
My one experiment with them(STX-RC) exploded into a thousand bits a few seconds after pulling the cover off. Never did find the anticlockwise grimble catch :(

If the internals are gummed up a good blast of WD40 or the like in every possible orifice of the shifter may help.

Re: Only shifting 4 gears

Posted: Mon Jan 07, 2013 6:36 pm
by Kaffine
bychosis wrote:
Mulger bill wrote:Simple, non scientific lever test (without knowing what sort of lever... :wink: )
Cable unhooked and shifter in 1st, hold the cable with some tension between your fingers and slowly click the shifter up to 8.
Do you get 7 smooth feeling clicks? Does the cable seem to pull the same amount each click?


Kinda what I meant, but testing the derailleur by pulling the cable by hand was a good one too.

As for shifters, I have heard, but not by experience, that dissassembly of any trigger style shifters allows some magic to escape and they cannot be reassembled.

YouTube is a useful additional resource for those who learn visually, it's helped me where a wordy descriptions miss. Picture's worth 1000 words, video must be worth at least a million.



Thanks Bychosis

I think that due to the bike being garaged for so long there must have been a small hole in the front shifters and some of the magic smoke has leaked out :cry: Ah well never mind, Understand there are springs under the cover that want to escape at the first opportunity so the cover stays on :D

I did take the bike for a 15km loosen-er just to see what falls off and it went surprisingly well and lots of fun, a few things I noticed, I only really need 5 rear gears and two forward anyway (just doing a coastal run and the decent hills are miles away), maybe upgrade the gearing later single front 10 rear. I'll remove the rear v brakes and replace them with discs just cuz a want too, Yes it does have the mount just not the rotor attachment, It's got the crappy RST shock on the front and due to its age I'm not sure if it can be replaced.

I'll make it a project bike, I think a good way to learn more about its workings.

Re: Only shifting 4 gears

Posted: Mon Jan 07, 2013 8:15 pm
by Wal42
You may not have to disassemble your shifters, I have had some issues in the past with some older ones, spray some penetrative spray into them, then allow them to sit then spray them some more, back the cable tension off & work them, keep spraying & working them, usually they'll loosen up.

I have pulled apart a set of LX shifters (off a late 90's ATX 870), it ain't rocket science, just look carefully when you separate the 2 parts, you'll see they're probably full of gunk (dirt, dried mud, crud mixed with dried lubricant), spray them liberally with degreaser, flush that out with penetrative spray then drizzle some chain lube in. They'll usually free up, if they don't you can still buy new 8speed Shim MTB shifters, they're really cheap, so just grab yourself some new ones.


Generally when you're resurrecting an older bike, you just have to chew through a few cans of lubricant spray & have some patience.

Re: Only shifting 4 gears

Posted: Mon Jan 07, 2013 9:35 pm
by Kaffine
I think magic dust is allergic to lube spray, I just lost a gear...

There is something seriously wrong with the shifter its making crunching sounds and there is no grit or mud in there is absolutely clean.,

I think its had its day ,don't know why the bikes only about 13 yrs old.. :shock:

Time to hunt down a new 8 spd..

anyone Perth?

Re: Only shifting 4 gears

Posted: Wed Jan 09, 2013 3:05 pm
by Kaffine
GIANT ATX 840 UPDATE

Picked up a donor HARO flightline last night with a busted rear derailleur bracket, transferred over the rear shifter/ brake combo (ugly but it works),rear disc brakes and wheels (with a lil be less aggressive tread). Now have spare H/D stem, Crappy shocks (SR Suntour XCR MLO with Lockout 100m maybe better than the RST 381 EL), Seat post etc etc.

Got a bit more experience in tuning gears, straightening rims and disc brake assembly.

My get some kms out of it then look at a 29er.

Cheers for all your help