rear mech issues

not going so smoothly this bike build up, i seem to have forgotten how to set and use gears 😀

just plopped the sram XO rear mech back on, its the same frame, same wheel, same cassette, same chain as before, yet the chains struggling to stay on the smallest cog and keeps trying to climb onto second cog. the mechs twitching away too.

ive looked at the little adjustment screw and its fully off the contact, so the mech is as far over as it can i think. i also havent connected the cable to it yet just to prove that its not cable tension keeping it from coming fully over.

the only other thing i can think of is the b-tension screw but im not sure what does. i think it sets gap between chain/mech and cog doesnt it? if anything its a little close, the cogs almost touching the chain, would this cause an issue?

hopefully youtube linky below.
rear mech youtube linky

thanks

Have you knocked the mech hanger? Check its alignment first.

Also, are you looking at the correct limit adjustment screw?

Add 1/2 turn of B screw to move mech away from cogs
Bent/misaligned hanger
Incorrect adjustment of limit screws (are you sure the one not touching is the lower limit screw?)
Is the stop tab in tbe right place and the hanger installed correctly

Have you knocked the mech hanger? Check its alignment first.

Also, are you looking at the correct limit adjustment screw?

it all looks aligned when i look from the back, it doesnt look like it should be trying to climb. dont think the hangers been knocked. i wondered if the gap between mech and cog (b screw) could make any difference? do you think this is too close?

also the lower jockey wheel is ‘spiked’, dont know if it should be or if its worn?

yes im sure its the right screw. furthest away from the frame, it also has an H by it.

thanks

EDIT:

Add 1/2 turn of B screw to move mech away from cogs

thatll be my next move tomorrow, thanks.

If you’ve loosened off the H limit screw after attaching the cable, it could be now be the cable that’s limiting the outward movement of the mech.

If you’ve loosened off the H limit screw after attaching the cable, it could be now be the cable that’s limiting the outward movement of the mech.

i havent attached the cable, just to prove this point.

thanks

i havent attached the cable, just to prove this point.

thanks

Sorry, I completely missed that the first time around!

Yes. In my opinion that gap between jockey and cassette is to close

Bottom jockeyvwheel doesnt look worn to me, it looks forked

Running gear could do with a good clean top

Yes. In my opinion that gap between jockey and cassette is to close

Bottom jockeyvwheel doesnt look worn to me, it looks forked

Running gear could do with a good clean top

cheers, ill have a play with the b-screw tomorrow.

any idea which replacement jockey wheel id need? are they all the same or will i need to search for a ‘sram XO lower jockey wheel’?

running gear looks dirty, and i spose it is, but i think it probably looks worse than it is. the chains just come out of a putoline bath, which whilst it doesnt clean it per se, i think it waxes/lubes the important bits?

thanks

well i screwed the b-screw in half a turn, no difference. looked from the back and altho it seems to be trying to skip and jump onto the 2nd cog, it really doesnt look like its the line thats causing this, the chain is just skipping.

further investigation on the lower jockey wheel does indeed look like its borked. ive taken it off now.

so, before i mess with anything else, ill get a new jockey wheel set and see how it goes.

any idea which replacement jockey wheel id need? are they all the same or will i need to search for a ‘sram XO lower jockey wheel’?

bump on this please?

thanks

I’d firstly borrow the tool you need to check the hanger isn’t bent – I had a brand new frame where it wasn’t aligned and I couldn’t get brand new gears to work until straightened.

How worn is the cassette / chain / chainring? It looks tired – but maybe the dirt isn’t helping.

Also – aren’t you meant to fully degrease / clean a chain before putting it in putaline?

ill ask around a few mates see if anyone has one, dont think ive ever seen one tho so not holding out much hope.

ill still need a new jockey wheel anyway, so nothing lost by getting sorted there and trying again if i cant get hold of a ‘hanger checker’.

thanks

Chain looks very worn which would potentially explain the nick of your jockey wheels.

borrowing a chain-wear checker next week, but out of interest, how can you tell if a chains worn just by looking at it? just looks like a dirty chain to me 😀

i havent actually ridden the bike yet since buying and repainting frame, so cant vouch for the mech/chain/cassette, but i spose it cant harm to get a new 9 speed chain anyway. its got a new front ring, itll have new jockey wheels, ill get a new chain too, i wont change the cassette yet tho as i want to prove 1×9 with it.

hopefully this will sort the issue and negate the need to check the hanger alignment.

thanks

Chain pins don’t look centred between the teeth, and sprockets – esp the smaller ones, look worn.

If you’ve a straight ruler (steel preferably) then just measure out twelve full links – they should come to 12″

Worn chains are more likely to skip in the smaller cogs as there’s fewer teeth to engage.

Mate, check the gear hanger. They never look out but 3 out of 4 of mine were.

Chain pins don’t look centred between the teeth, and sprockets – esp the smaller ones, look worn.

If you’ve a straight ruler (steel preferably) then just measure out twelve full links – they should come to 12″

ah gotcha, thanks.

Mate, check the gear hanger. They never look out but 3 out of 4 of mine were.

had a look at tool prices and they scared me, so i assume best bet is to take it into a shop and ask them to check it?
out of interest, how easy is it to bend back a steel frame if it is indeed needed? its just had a repaint so dont want to start chipping/cracking the paintwork.
hopefully itll just be the jockey wheels and chain thats causing the skipping…..

Chains do stretch, but by very little – the rollers on the pins wear though, which means that the effective pin to pin distance increases, giving the same effect as stretch, so a chain measuring tool is more use in gauging wear than a ruler.

A quick way to guess how worn a chain is is to twist it and compare that to a newer one. Worn chains twist loads more that’s why the shifting goes awry.

The only thing you can tell for sure from that picture is that the b tension is insufficient and that jockey wheel is ****.

The small sprockets are out of focus and the angle of the photo doesn’t let you see the relative position of the pins between the teeth with any clarity.

You can maybe draw some conclusions like that KCNC jockey isn’t original -if the rest of the running gear is it’s almost certain to be worn if it’s lived long enough to go through two sets of jockey wheels.

Every single one of our bikes had a bent hanger. I would (now) check them first always.

update time. mate came round with his chain checker and confirmed that out of the 2 settings, ‘fked’ or ‘fked fked’ it was indeed the latter option.

new kmc chain, 2 new superstar jockey wheels, mates also given me a better cassette than i had on (hes a good lad isnt he) and the result is……… its still climbing on the smallest cog. probably even worse than before.

so, we’re now left with either a bent mech, or bent hanger which is your favoured option so far i think 🙂
mate says hes going to attempt to make an alignment tool at work so we can check it (told you he was a good lad didnt i).

the videos ive watched on youtube so far show sacrificial hangers, mines a steel mk1 soul and its part of the frame. there shouldnt be any problem bending it should there? no chance of it snapping? is it ok to bend a steel hanger?

also i wondered about the paint on the hanger. ive just had it resprayed and so its obviously got a new coat on it. thats fine isnt it? doesnt need to be a ‘faced’ finish?

thanks

well, the plot thickens, update time…..

mate came round with his home-made ‘hanger-checker’, found out it was about 10mm out and we straightened it best we can. however, still hasnt cured it, chain still constantly trying to climb from smallest cog up to next one.

next was to examine cassette. mate says he thinks cassette looks too close to the frame maybe (and hence the chain too, almost rubbing the frame), and thats why the chain might be trying to wander back.

and with the chain further up the cassette

we measured the gap from edge of cog to frame, its about 1/8th of an inch.
he measured the gap on his, he says its about 3/16ths. deal-breaker?

i also wondered whether the wheel hub itself may be different from normal, maybe for an 8 speed or something, so took the cassette off and measured it. its 35mm, that the right width?

just to re-confirm, cable isnt connected to mech so mech is at its furthest point across by itself, limit screw is as far out as poss, so we believe the mech cannot come over any further. new chain and decent condition cassette.

whats left? i can only think of a bent mech itself, or, that the chainline from the single ring up front to smallest cog is such that its trying to pull the chain inline all the time.

thoughts please?

fit his wheel to your bike to test ?

Assuming the hanger is now straight (10mm out sounds a lot) then I reckon perhaps your mech is borked. Which having seen the condition of the jockeys above and the chain / cassette being very worn is quite likely. It could be bent or have too much play in it.

Based on your measurement from smallest cog to frame yours is only 1/16th closer? As long as the chain isn’t touching the frame I’d have thought that was ok.

On chainline your frame must be non boost so as long as it’s a non boost chainset and / or non boost ring with the correct bb spacers that shouldn’t be the issue.

Have you tried pulling the mech down towards the smallest cog whilst the chain is trying to skip back up to the next cog? IE is something yet to be established preventing the mech moving all the way to its outer limit?

As Davesport. I’d bet, after all what you have done, that it’s the mech. A tired/stretched spring in the mech?

Have you changed or removed the bb or cranks? My best guess is that the chainline is off, which could be caused by a change of cranks or bb (or frame) and/or not enough spacers on the drive side bb cup.

fit his wheel to your bike to test ?

good call. mentioned it to him, he says his is 130mm, mine will be 135mm, but should still prove a point?

Based on your measurement from smallest cog to frame yours is only 1/16th closer? As long as the chain isn’t touching the frame I’d have thought that was ok.

correct, 1/16th closer.

Have you tried pulling the mech down towards the smallest cog whilst the chain is trying to skip back up to the next cog? IE is something yet to be established preventing the mech moving all the way to its outer limit?

another good suggestion, ill try this when theres a spare pair of hands around.

Have you changed or removed the bb or cranks? My best guess is that the chainline is off, which could be caused by a change of cranks or bb (or frame) and/or not enough spacers on the drive side bb cup.

hmmmmm yes i have. stripped it all for a respray and entirely possible i may have not got it quite right putting bb back in with correct spacers where they should be i spose. but, on the point of chainline being off, im not sure that would have an effect would it? ive gone from 3 at the front to a single ring, so effectively in the middle of the old chainset. and on the old chainset i should still have been able to go small/small still shouldnt i, which would be even more of a skewed angle?

thanks for the suggestions.

just tried one of the suggestions above, tried putting pressure on the mech (both ways actually) whilst pedalling to see if it improved. i think it did improve it, its not climbing as much now.
what it is doing is the same as i originally mentioned, the mech is sort of ‘clicking’ and twitching all the time as the chain goes through it, even when not trying to climb. ive put my finger on the bottom cage part and thats where i feel the click most. gut feeling is that theres probably an issue with the mech.
it doesnt help that the front ring is an oval, so the mechs moving all the time anyway, i think itd be easier to diagnose if it was round so the mech was totally still.

i spose the only way to test that is try another mech. im loathe to spend too much on diagnostics so will try and find a spare from a mate maybe.

if i do have to buy new, is it worth getting a ‘longer’ mech to future proof for 10 or 11 speed say? to give me clearance over bigger cogs? or if i did that would i have problems using it with 9sp?

thanks

The mech will constantly move forward and back a little with an oval chainring i think.

If you find the mech is borked I’d be tempted just to change the mech / cassette / shifter / chain and move to new Shimano Deore. Either 10 or 11 speed I believe it comes in and it was pretty cheap when I tried to put a budget group together for my nephew. Went Sunrace 11-46 cassette / deore 11 speed mech / slx 11 speed shifter / Sram 11 speed chain as those were the cheapest of each bit I needed. Works pretty well once I straightened the mech hanger on the brand new frame (Brand X Ht).

If for some reason the mech can’t move out enough to suit the new frame try putting a thick washer between the mech and the hanger. I had to do that 30 odd years back to make a Trigger’s Broom of a bike work.

Wasn’t it that generation of Sram mechs that showed pivot slop after extended use which caused the parallelogram to go a bit skew-wiff, with the end result being that the cable clamp assembly somehow fouled another part of the mech, preventing it being able to fully drop into the 11T sprocket? Got a pic of the cable clamp area while in or trying to get into 11T?

Have you tried pulling the mech down towards the smallest cog whilst the chain is trying to skip back up to the next cog? IE is something yet to be established preventing the mech moving all the way to its outer limit?

My idea was you did this on a workstand so it could be done singlehanded. Hope you get sorted…most annoying when things like this happen.

My idea was you did this on a workstand so it could be done singlehanded.

thats what i did in the end (see my post above? ^^) it made it a bit better, it wasnt trying to climb as much, but mech still clicking and twitching whilst the chain was running through it.

Got a pic of the cable clamp area while in or trying to get into 11T?

ill try and get a pic/vid tomorrow.

If for some reason the mech can’t move out enough to suit the new frame try putting a thick washer between the mech and the hanger. I had to do that 30 odd years back to make a Trigger’s Broom of a bike work.

another good suggestion, and ill look into that also.

If you find the mech is borked I’d be tempted just to change the mech / cassette / shifter / chain and move to new Shimano Deore. Either 10 or 11 speed I believe it comes in and it was pretty cheap when I tried to put a budget group together for my nephew.

as per my previous question, would the 10 or 11 speed mech be compatible with 9 speed too if i didnt want a full conversion, yet still be ‘future-proofed’?

thanks.

not sure how successful this will be, but here goes……

youll need your sound turned up to hear the clicking. hope it also shows “Got a pic of the cable clamp area while in or trying to get into 11T?”

1st video

2nd video

Tried some OEM jockey wheels? Most aftermarket ones are awful IME.

Tried some OEM jockey wheels? Most aftermarket ones are awful IME.

jockey wheels are new superstar jockeys.

well finally sourced a cheapo sram 9sp mech on facebook for a fiver, thought itd at least help me eliminate the mech from the problem.
its a shorter cage so cant reach the big cog, but with the screw wound right back so the mech comes as far over towards the small cog as possible, i still have the same problem, still climbing onto second cog and dropping back down all the time..

i know my mates been round with his home-made alignment tool, but is that all thats left for me now, alignment? its not a replaceable hanger, its all part of the steel frame, so do i now need to admit defeat and take to a shop to check?

thanks