Gazlars gears skipping mk2
Gazlar
Posts: 8,084
From my post the other week which I cant find
Gears were slipping in the largest 3 sprockets at the rear, I thought under load, but turns out its now all of the time.
I checked the frame bearings to elimate frame flex causing this issue and striiped the freehub to make sure after i rebuilt it it wasnt just the pawls slipping.
Anyway heres the state of play, after a slow pedal up and down the alley this is what is happening.
shift down from the largest sprocket to the next, its overshiftingthen contantly changing up then back down to where its overshifted too, the same happens the next sprocket down, the mech arm keeps pulling forward at this point. I increase the cable tension at the shifter to the very point it stops doing this. When the tension is increased to this point it will not change right the way down to the smallest sprocket. I decrease cable tension to the very turn this drops in at and work up through the gears, then it struggles into the larger sprockets and then overshifts when changing down through the larger couple.
set up, xt mech, kmc x9 chain, xt cassette, superstar double chain roller, slx shifter, slx 36/22 double chainrings on deore chainset. Its doing my nut now
Ta folks you know its much appreciated as I'm not a huge techy but i'll have a go
Gears were slipping in the largest 3 sprockets at the rear, I thought under load, but turns out its now all of the time.
I checked the frame bearings to elimate frame flex causing this issue and striiped the freehub to make sure after i rebuilt it it wasnt just the pawls slipping.
Anyway heres the state of play, after a slow pedal up and down the alley this is what is happening.
shift down from the largest sprocket to the next, its overshiftingthen contantly changing up then back down to where its overshifted too, the same happens the next sprocket down, the mech arm keeps pulling forward at this point. I increase the cable tension at the shifter to the very point it stops doing this. When the tension is increased to this point it will not change right the way down to the smallest sprocket. I decrease cable tension to the very turn this drops in at and work up through the gears, then it struggles into the larger sprockets and then overshifts when changing down through the larger couple.
set up, xt mech, kmc x9 chain, xt cassette, superstar double chain roller, slx shifter, slx 36/22 double chainrings on deore chainset. Its doing my nut now
Ta folks you know its much appreciated as I'm not a huge techy but i'll have a go
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Comments
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is the gear cable new?0
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I have just changed it, but it was doing exactly the same with the old one too0
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still it sounds like a cable problem, could it be the routing of the cable?0
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Is the H limit stop exactly right?0
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H limit is set right, and i've tried it set as far wound out too, ie so the chain would go further than it needs to just out of interest.
The outer is practically new as is the cassette/chain, they were brand new when I built the bike the end of June, i only really changed the cable because the end had frayed ever so slightly taking the ferrule off so I couldnt rethread it. The roller doesnt seem to make a difference, i thought the chain may have been catching the lip and pulling the derailleur arm across slightly but i pushed the device up out the way and its made no difference
The only other thing I can think of is the cable routing maybe or for some reason the rear mech/shifters are not moving through the index correctly as with the tension slackened off so as the chain will drop into the smallest sprocket and still make it up to the largest just about, its just the second and third largest it shifts down past them and then up and down. I stripped the mech yesterday and cleaned and oiled it.
just baffling0 -
Turn the H stop out half a turn.0
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I have done ss, I set the stop spot on with the cable tension to the point it stops into the bottom sprocket. Then I move through the gears, reset the tension to the point the larger sprockets index correctly then work back down through the gears, when I get to the bottom no amount of gradual turning out of the h limit gets the chain dripping back onto the smaller sprocket.
There seems like there is between a turn and half andtwo full turns odd the adjuster barrel between the point in tension where the gears drop down into the smallest sprocket and the point that the larger sprockets index correctly0 -
Just to get it clear as you keep changing the words you use.
It's skipping only on the 3 largest (nearest spokes) sprockets at the rear, and you think it's because it is shifting from one sprocket to the next. (please stop introducing bottom and smaller)....
Have you checked the QR is tight?
Mech hanger bent? This has most effect on the larger sprockets as the guide jockey is further from the mech pivot point so a bent hanger moves it further sideways.Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.0 -
Not so much the largest, but the next two down moreso when down shifting, it overshifts then jumps back up towards the spokes then back down. Mech hanger is straight and its a rear which Is tight0
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dude, you really need to get your head around high and low gears, and changing up and down. It's really bloody difficult following what you're trying to say.0
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Just looked through what I've put, if I say down I'm meaning down, away from the spokes and up up the sprockets towards, I realise I babble a bit so hopefully this helps0
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Exactly, in a car 2nd gear is changing up from 1st, so why down on your bike?Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.0
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if the mech is spring forward, thats normally the first sign of a dead chain. might be that dead chain in combination with certain chainlines/sprockets is the issue.A Flock of Birds
+ some other bikes.0 -
benpinnick wrote:if the mech is spring forward, thats normally the first sign of a dead chain. might be that dead chain in combination with certain chainlines/sprockets is the issue.
I thought that, but it with a different chain and chainset set up, and doesn't pull forward when the cable tension is
, but that's when it stops shifting into the smallest sprocket. Its certainly something I will near in mind.
Think next logical step is to change the outer, maybe the length too make it a shade longer and work from there. Intrying to work logically through what could be causing it before going to the more expensive items to replace. Think after a couple more tats with it I'll be packing it off to the lbs0 -
I'd go with new cable outer as the next step, too. You've already done cassette/chain.
Might also be the spring in the derailleur has gone a bit weak, although a new-ish XT should be ok.0 -
Just had another fettle and its so close now, it moves perfectly through all the biggest 8 sprockets both ways up and down, and also in Gazlars definition of up and down.
It will just not quite drop into the smallest, even with the h screw wound right out, but the mech will squeeze just a little by hand and then it drops in which I think may go along with the mech spring being a tad weak,
Any thoughts0 -
Are you sure it's sitting on the limit screw when on the smallest sprocket and not on the cable tension?
I find it's best to set limit screws before attaching the inner.0 -
Dirtydog11 wrote:Are you sure it's sitting on the limit screw when on the smallest sprocket and not on the cable tension?
I find it's best to set limit screws before attaching the inner.
Thats exactly whats happening, but not because the limits aren't set right. I set the limits without the cable attatched and the barrel adjuster slackened off. The chain will move through the complete range of gears like that but will jump about the 2nd and 3rd largest sprockets when shifted into them. If I adjust the tension of the cable and tighten it the gears move perfectly through the index from large to small, but the tension then holds the mech, stopping it from sitting on the h limit screw, and preventing me from shifting into the smallest sprocket.0 -
What mech is it? If it is a shadow make sure the flappy bolt arm on top is attached pointing backwards and the jockeys are on correctly.0
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Or just stop trying to pretend you have a bike and carry on stalking Foxc.I don't do smileys.
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Chunkers1980 wrote:What mech is it? If it is a shadow make sure the flappy bolt arm on top is attached pointing backwards and the jockeys are on correctly.
Head is on pointing backwards, by jockeys on correctly i presume you mean bolted up right and running smooth
gone down the new cabling new mech route, its due a change anyway really and picked one up pretty cheap, the old one can sit in my box of bits or go in the bin depending on what happens.
Cheers guys all good points that i've either already tried or tried this afternoon with no joy, so its pretty much onto the last couple of things now, i'll try them and report back0 -
Quick update, all now sorted new rear mech fitted and working fine, on comparison of the two, the spring did seem a little weaker and was not quite closing up right.
Cheers Guys0
