Rear mech clips spokes in first gear?

fudgey

I bought a new bike in Jan and it came partially built, all i had to do was fit the bars, front wheel and gear cables.
Its on 11 speed shimano 105 its a Colnago CX Zero alloy.
Of course this meant indexing the gears which was done very easily and out on the road the gears are generally very slick and change with no messing - infact its the best shifting bike i have had!

The only issue is when its in first gear, so 34-28, if i spin the cranks with no load ie on a stand etc its fine but the rear mech where the upper jockey wheel is, it is literally 2mm away from the spokes. Now when there is a bit of pressure even spinning like buggery on the flat in first gear the rear mech clips the spokes, but its much worse when climbing a steep hill. It only makes contact on only 3 pairs of spokes where they cross over. There is a very slight lateral movement to the rear wheel, i wouldnt say its badly buckled but i guess truing it might help.

Its enough to have taken some paint off the mech cage by the upper jockey and the spokes mentioned.

I have fitted a brand new rear mech hangar, adjusted the limit screws so once its in first gear the mech will not move any more on the lever, and its adjusted so it just goes into first gear and i had added more b tension.

But it still does it.

It seems to be when force is applied to the cranks, either left or right that the rear mech moves in the direction of the wheel. I tested this by cable tying the rear brake lever to the bar so it was on hard and held the wheel and then with the bike upside down pressed on the cranks. Even with hand pressure the mech moved, so with my full weight on it it will of course move more.

Anyone have any ideas of other things i can try? I need a cassette tool then ill swap my rear wheel off my other colnago, same artemis wheels but its a 10-speed 105 and try that.
Not sure if there should be a spacer etc behind the cassette? As said i have not taken it off yet so unsure if it should have one. (Although arnt the spacers only for 9 or 10 speed cassettes?)

Cheers for reading.

ugo.santalucia

At a guess, if you get a bigger cassette the problem should go away... try an 11-32

ben-----

> … adjusted the limit screws so once its in first gear the mech will not move any more on the lever, …

Not an expert, but so far as I know, that's not how you're supposed to adjust the L limit screw(?). I thought you were supposed to disconnect the gear cable from the derailleur entirely, gently spin the cranks in the normal direction while pushing the derailleur across with your thumb, and set the L limit screw appropriately like that. So you're not relying on the gear cable/shifters when setting the screw. Maybe it wouldn't make any difference but might be worth a go.

k-dog

^ I don't do it like that - but you're right about not using the shifter. I pull the cable from under the downtube and turn the limit screw until it can't be in the lowest gear, then back off a bit so it can but you can't overshift. Doing it that way means that you can release the tension and then make sure you can get back into that gear easily - seems easier than pushing the derailleur.

I would check the hanger alignnment - just because it's new doesn't mean it's straight. Straightforward with the right tool. A little bend can make a big difference in the position.

The wheel shouldn't be that close but if it's wobbling that won't be helping. I would have it trued and tensioned - it's maybe moving more than it should when you're out of the saddle and that would help.

You definitely want to sort it before the spokes get weakened and the wheel explodes one day - or the wheel moves very slightly more and you catch the derailleur and rip it off.

Monty Dog

+1 on checking hanger alignment. The mech pinging on the spokes is a disaster waiting to happen - you could easily trash your wheel and frame in the process. I would take it to a bike shop to get it checked - for £10 you could save yourself a whole lot of grief.

ugo.santalucia

yep, for some reason I thought you had the chain clipping the spokes. If it's the mech, you need to align the hanger

StillGoing

ben----- wrote:

> … adjusted the limit screws so once its in first gear the mech will not move any more on the lever, …

Not an expert, but so far as I know, that's not how you're supposed to adjust the L limit screw(?). I thought you were supposed to disconnect the gear cable from the derailleur entirely, gently spin the cranks in the normal direction while pushing the derailleur across with your thumb, and set the L limit screw appropriately like that. So you're not relying on the gear cable/shifters when setting the screw. Maybe it wouldn't make any difference but might be worth a go.

This. Disconnect the cable to set the L limit by pushing the derailleur below the biggest sprocket on the cassette. It should have the upper jacket wheel directly under the sprocket. Set the H limit, and reattach the cable with the shifter set for the highest gear.

fudgey

Ah bugger, i plan on taking this bike to spain this year so was going to fit an 11-32 anyway, so after reading ugo's first post i had high hopes ha.

Ok ill have a look at re indexing the rear mech as suggested above. The mech seems to move from the bit that is clamped to the frame, the bolt is tight but the bit that swings for/aft which the B tension screw adjusts the pressure on, is what seems to have a little side to side movement. Ill try and get some pics tomorrow if it helps.

As for aligning the hangar, how is this done? Never done it before.

Thanks for the replies chaps.

k-dog

http://www.parktool.com/blog/repair-hel ... -alignment

StillGoing

Fudgey wrote:

Ah bugger, i plan on taking this bike to spain this year so was going to fit an 11-32 anyway, so after reading ugo's first post i had high hopes ha.

Ok ill have a look at re indexing the rear mech as suggested above. The mech seems to move from the bit that is clamped to the frame, the bolt is tight but the bit that swings for/aft which the B tension screw adjusts the pressure on, is what seems to have a little side to side movement. Ill try and get some pics tomorrow if it helps.

As for aligning the hangar, how is this done? Never done it before.

Thanks for the replies chaps.

If the derailleur is screwed in tight to the hanger, but the derailleur still moves, check that the screws holding the hanger onto the frame are tight and apply some loctite.

As for adjusting the hanger for straightness; there is a tool you screw into the hanger and can apply pressure to bend it into shape. Some apply an open end spanner to the hanger to do the same thing. I remove the hanger, heat it up and bend it and then check it on a known flat surface.

daniel_b

Mine did exactly this, andin my instance it was a bent rear hanger.

Bought a tool, and it's a comparitive doddle to sort, and makes the world of difference, have used it on several bikes now, well worth the investment, paid for itself many times over.

fudgey

cheers chaps, ill look at buying a tool.
i have borrowed a cassette tool and chainwhip and have just removed the cassette off my other wheel (and cleaned in the parts washer) so ill swap the wheel over in a bit and have a go at re indexing the mech.
if still no joy ill go down the route of checking the hangar.

re the new hangar, it is held on with loctite'd screws and the mech is tight to the hangar.
The movement i mentioned is in the body of the mech.

svetty

Until you know the hangar is correctly aligned all other adjustments are premature. Once this is correct you have a proper foundation upon which to adjust the limit screws and cable tension. I assume you have the correct spacers for your wheel/cassette combination installed?

thegreatdivide

I can pretty much guarantee that it's what the chaps above have said - it's a bent hanger. No need to buy the tool, just take it to a good bike shop and get them to do it for a fiver. It's a 10 min job max and it'll avoid having to buy a new hanger when you snap it the first time you try and straighten it because I can also guarantee that'll happen too ;-)

fudgey

I think that is the next step chaps.
Took the cassette off and it would seem that the other wheel has a slightly shorter free hub and the 11 speed cassette would not fit. It was approx 1.5mm shorter so i cleaned it and reassembled onto the original wheel and went for a ride at lunch time. Its still the same unsurprisingly.
I do have a set of Vision Trimax T35 carbon/alloy clinchers that will take an 11 speed cassette, but it has flat aero spokes so i wont try the wheel on the bike as it will end up very expensive if it goes wrong...

Ill speak to my cycling mates and see if they want to club together to buy the straitening tool.
I get the idea of taking bikes/cars to the appropriate places to have work carried out - but i wont learn anything by doing that so i tend to DIY as much as possible.
And i have a few bikes, so do my mates so we should all benefit from it.
I know the hangers bend easily as on one ride not long after buying the bike i got fed up with it, so what i thought was a gentle tug bent the thing out 45 degrees
needless to say i couldnt bend it back in enough to get first gear, so had second or third onwards. it made the hills a struggle but i kicked my mates ar$es up them haha..

Oh the new hangar was put on the edge of a steel rule and seemed ok for flatness etc before i fitted it.

k-dog

Testing it for flatness isn't really of any use - it's a combination of frame alignment and hanger alignment so once you screw a flat hanger onto the frame it may be a bit off - 10 and 11 speed are very sensitive.

Monty Dog

As the bike is only 3 months old and if you haven't dropped/ crashed it then I'd ask the shop you bought it from to sort it..swapping wheels, fiddling with gears isn't going to change anything if the mech hanger is wonky. I've seen new frames off because of too much paint on the frame drop-outs

fudgey

Spent a few mns earlier checking it over again, and from what i can see, as the wheel rotates there are 3 pairs (that cross over each other) that get very close to the mech. The res of them are a good couple of mm away. I moved the brake off centre and the wheel is very slightly out of true, but not where its catching i dont think.
I cant see that the hub flange is warped, tried to take a video on my phone but i cant hold that still and spin the wheel. Will try and remember to take my lads telescope tripod to work tomorrow and use a propper camera. (Left the bike at work as i go in early and ride at lunchtimes most days)

So, before i go bending things i think it does look like the wheel is at fault here, but really cant see whats wrong yet.

Yes i,could send the bike back, but ill be left without a usuable bike for a while. If it comes to it then that is what i will do.

daniel_b

thegreatdivide wrote:

I can pretty much guarantee that it's what the chaps above have said - it's a bent hanger. No need to buy the tool, just take it to a good bike shop and get them to do it for a fiver. It's a 10 min job max and it'll avoid having to buy a new hanger when you snap it the first time you try and straighten it because I can also guarantee that'll happen too ;-)

Just to give my personal experience on this, I have successfully adjusted, yeh alright, bent back into shape, 4 rear hangers and none have snapped on me.

I think the key is to do it little by little, and small tweaks here and there, and then check and recheck.

keef66

I've had the mech strumming the spokes after falling off and apparently bending the hanger; quite a sphincter tightening moment! Luckily no other damage and managed to limp home without the lowest 2 gears. Crudely straightened the thing with an adjustable spanner.
I subsequently bought the proper hanger alignment tool. Much easier and more precise. Amazing how far out they can be, even from new. Which reminds me, the winter bike is sounding like it might need attention; the mech cage is briefly tickling the rear spokes when I change right down into the lowest gear :shock:

ben-----

> I subsequently bought the proper hanger alignment tool. Much easier and more precise.

I saw a YouTube video where someone, instead of a proper tool, used two longish threaded bars of a particular width. First one was screwed in, using bolts on the threaded bar, in place of the back wheel – so going along the same line as the rear wheel axel. Second one screwed in where the derailleur goes. (Obviously the rear wheel and derailleur need removing first.) Then it's just a question of looking at the two bars sticking out; are they parallel?, yes good, no, hanger's bent. Does that work OK? Anyone tried that?

keef66

You can also do it fairly accurately by using a spare wheel with a threaded axle; the screw thread is the same dia / pitch as the mech mounting bolt.

Screw it in to the mech hanger and then measure from the spare rim to the rim of the rear wheel where they cross.

fudgey

I tried Ben's approach above last night, i have a chain retaining axle thing for cleaning the chain, fitted that and a long 8mm screw secured with nuts.
The screw was straight and inline with the axle and i measured with a vernier the distance between the two, this was also the same.

I then fitted the cassette to my Vision T35 wheel and fitted that, the spokes were a good 8mm away from the mech, so with that wheel fitted it would be perfectly fine
I then fitted the 11 speed cassette to the other 10 speed artemis wheel i have, well 10 of the gears the spokes on that wheel were also very close..
Then reassembled the original wheel and corrected the very slight buckle and tightened the non drive side spokes as they were not as tight it seemed as the drive side ones, but it was raining heavily after so i have not yet ridden the bike to test, but from what i could do in the garage im sure its still the same.

Anyway, i have been emailing pics to the supplier today and they have agreed to send me an upgrade set of wheels!

Semantik

Fudgey wrote:

I have fitted a brand new rear mech hangar, adjusted the limit screws so once its in first gear the mech will not move any more on the lever, and its adjusted so it just goes into first gear and i had added more b tension.

.

Can you answer the following ?

Have you set the low limit screw at its optimal setting? ie have you screwed it in a bit more so the mech cage sits further away from the spokes but still (just) engages 1st gear? Even just another half a turn could be enough to keep it away from the spokes. You really don't want to ride that bike in the hills until it's sorted.
Also it would be very unusual (tho' not impossible) for a new mech hanger(not previously fitted to a frame) to be bent or out of alignment.

Monty Dog

Fudgey wrote:

Then reassembled the original wheel and corrected the very slight buckle and tightened the non drive side spokes as they were not as tight it seemed as the drive side ones,

Really? You do not appear to understand the concept of wheel dish and as most rear wheels are asymmetric, then spoke tension on the non-drive side is less than the drive side.

It would appear to me that your mechanical endeavours are likely to result in an expensive and perhaps catastrophic outcome for your bike - I would strongly recommend you put the tools down before it's too late....

fudgey

Semantik wrote:

Fudgey wrote:

I have fitted a brand new rear mech hangar, adjusted the limit screws so once its in first gear the mech will not move any more on the lever, and its adjusted so it just goes into first gear and i had added more b tension.

.

Can you answer the following ?

Have you set the low limit screw at its optimal setting? ie have you screwed it in a bit more so the mech cage sits further away from the spokes but still (just) engages 1st gear? Even just another half a turn could be enough to keep it away from the spokes. You really don't want to ride that bike in the hills until it's sorted.
Also it would be very unusual (tho' not impossible) for a new mech hanger(not previously fitted to a frame) to be bent or out of alignment.

Yes, set it up 3 times now and the latest time following this guide http://www.parktool.com/blog/repair-hel ... -section-6 which wasnt far off how i do it anyway.
I have set the low limit so as you say it will just go into first gear. It doesnt like being back pedaled much tho as its a bit noisy with the chain catching.
This helped but there was still a very slight twang under load.

fudgey

Monty Dog wrote:

Fudgey wrote:

Then reassembled the original wheel and corrected the very slight buckle and tightened the non drive side spokes as they were not as tight it seemed as the drive side ones,

Really? You do not appear to understand the concept of wheel dish and as most rear wheels are asymmetric, then spoke tension on the non-drive side is less than the drive side.

It would appear to me that your mechanical endeavours are likely to result in an expensive and perhaps catastrophic outcome for your bike - I would strongly recommend you put the tools down before it's too late....

No, you are quite correct i have never read up on how to build a wheel, been on training courses or watched any youtube videos. But i have built a few and they have never lost a spoke, exploded or killed anyone.

How is one to learn if they dont have a go?

dennisn

Fudgey wrote:

Monty Dog wrote:

Fudgey wrote:

Then reassembled the original wheel and corrected the very slight buckle and tightened the non drive side spokes as they were not as tight it seemed as the drive side ones,

Really? You do not appear to understand the concept of wheel dish and as most rear wheels are asymmetric, then spoke tension on the non-drive side is less than the drive side.

It would appear to me that your mechanical endeavours are likely to result in an expensive and perhaps catastrophic outcome for your bike - I would strongly recommend you put the tools down before it's too late....

No, you are quite correct i have never read up on how to build a wheel, been on training courses or watched any youtube videos. But i have built a few and they have never lost a spoke, exploded or killed anyone.

How is one to learn if they dont have a go?

I'm with Monty on this one. Find out how to do the job correctly before you embark on anything like wheel-building.
You can't do a decent or even fair job on wheels with zero experience, zilch training, and no guidance. A very poor and undependable wheel is the best you'll get. In no uncertain terms - JUNK. (and a waste of money and parts)

fudgey

Oh really. The last one i totally rebuilt with new nipples and spokes last year has been perfectly fine thanks.
I have also modifed/rebuilt several car engines before, that last one was a turbocharged 2.0l Zetec from an old Mondeo.
That went on to make 400bhp in my old track car..
Oh, i am not a mechanic either, nor been on any engine building courses. I have read the odd Haines Manual however...

thegreatdivide

It's a bent rear mech hanger. Take it to a bike shop. Get the job done properly with the correct tools.

In the meantime don't attempt to ride the bike because a sheared rear mech in the spokes isn't much fun.

k-dog

Semantik wrote:

Also it would be very unusual (tho' not impossible) for a new mech hanger(not previously fitted to a frame) to be bent or out of alignment.

I don't think that's right - it's not the straightness of the hanger which is the issue but the combination of hanger and frame - and the 2 will never be perfect.

The hanger needs to be installed and then assessed properly so that it's square to the wheel.