Bike Mechanics Impart Their Wisdom On Vorb

OliverBendix · *by **OliverBendix** on Fri 4/Jun/10 10:46am*

It is a Shimano chain, but it's had some serious cleaning and re-lubing due to wet 4WD track mud, and it's a square taper BB, so not much option for chainline adjusting.

pushbikerider · *by **pushbikerider** on Fri 4/Jun/10 10:51am*

is the front mech set up correctly, especially in regards to height off the big ring?

yeahnah · *by **yeahnah** on Fri 4/Jun/10 11:00am*

As PBR said check the frt derailleur hight and angle first.
Have the chain rings been removed at all? Most of them work best when they are all in alignment with each other and the crank so the shift pins/gates all line up.

OliverBendix · *by **OliverBendix** on Fri 4/Jun/10 11:29am*

The front mech looks too high - but it won't go any lower without the end of the cage hitting the chainstay. It's not the stock mech for this bike as that one didn't give enough tyre clearance. They're both Deore, but this one has the clamp band at the top and I think the other had the clamp at the bottom.

yeahnah · *by **yeahnah** on Fri 4/Jun/10 11:55am*

If the arc of the deraileuers cage is not matching the big c/ring that could likely be your problem as the shapes on the inside of your cage wont be lined up just right .

What bike is it ?The frt der shouldnt get too close to the tyre .Some 29ers are a pain for that

OliverBendix · *by **OliverBendix** on Fri 4/Jun/10 12:08pm*

Fisher Mamba. With the current derailleur it just fits a 2.25 Ardent.

Sounds like I at least know what the trouble is now, thanks guys.

danose · *by **danose** on Fri 4/Jun/10 1:31pm*

OliverBendix wrote:Fisher Mamba. With the current derailleur it just fits a 2.25 Ardent.

Sounds like I at least know what the trouble is now, thanks guys.

think of it's as gods way of telling you to go 1x9 :satan:

will 100% fix your problem - and I'm sure you don't really want functioning knees anyway

rackerrack · *by **rackerrack** on Sat 5/Jun/10 10:40am*

So is it normal to have a bit of oil come out of the air valve on a dhx after is had a service?
Had a bit come out when I disconected my shock pump.

yeahnah · *by **yeahnah** on Sat 5/Jun/10 12:21pm*

Just a dribble is normal.

OliverBendix · *by **OliverBendix** on Sat 5/Jun/10 5:38pm*

danose wrote:
OliverBendix wrote:Fisher Mamba. With the current derailleur it just fits a 2.25 Ardent.

Sounds like I at least know what the trouble is now, thanks guys.

think of it's as gods way of telling you to go 1x9

will 100% fix your problem - and I'm sure you don't really want functioning knees anyway

Today I find that one of cogs in the cassette has cracked! Bicycle god must be telling me to singlespeed it. :crazy:

Actually, it's not an entirely unappealing idea...

Spokes · *by **Spokes** on Sat 5/Jun/10 5:49pm*

OliverBendix wrote:Mechanical gurus - why does my chain sometimes jam while shifting down to the granny or middle on the front? This is with a new chain and rings, cleanish, lubed, and happens while I'm shifting under no or very low load - just spinning the chain over gently, not putting any power in.

It seems like the chain shifts down OK when the derailleur hits it, but the section remaining on the bigger ring doesn't drop off. The result is that the chain gets jammed in the derailleur cage or against the frame.

As I haven't done this under any tension, I haven't broken anything yet but with this and some ordinary mud-related chainsuck a few weeks ago I've lost a fair bit of chainstay paint off a nice new frame. The chain hasn't dinged the metal too badly - just some surface scratches. I had armoured it up with tape etc but this morning's failed shift to the middle ring pulled the tape off. There's very little clearance there, just a couple of mm between rings and frame, which I suppose is a compromise for more tyre clearance.

Any suggestions for fixing the problem, and armouring the chainstay to save it from future occurences or ordinary chainsuck will be most welcome.

Are the new rings the same brand as the crank?

FSR_Man · *by **FSR_Man** on Sat 5/Jun/10 6:18pm*

Spokes wrote:
OliverBendix wrote:Mechanical gurus - why does my chain sometimes jam while shifting down to the granny or middle on the front? This is with a new chain and rings, cleanish, lubed, and happens while I'm shifting under no or very low load - just spinning the chain over gently, not putting any power in.

It seems like the chain shifts down OK when the derailleur hits it, but the section remaining on the bigger ring doesn't drop off. The result is that the chain gets jammed in the derailleur cage or against the frame.

As I haven't done this under any tension, I haven't broken anything yet but with this and some ordinary mud-related chainsuck a few weeks ago I've lost a fair bit of chainstay paint off a nice new frame. The chain hasn't dinged the metal too badly - just some surface scratches. I had armoured it up with tape etc but this morning's failed shift to the middle ring pulled the tape off. There's very little clearance there, just a couple of mm between rings and frame, which I suppose is a compromise for more tyre clearance.

Any suggestions for fixing the problem, and armouring the chainstay to save it from future occurences or ordinary chainsuck will be most welcome.

Are the new rings the same brand as the crank?

is the chain jamming between rings? if so put them on the right way around,
or is the cahin jamming between BB and crank/22t? if so set font mech up properly. should be on straight, about 1mm gap between the deralieur cage and the chain when in the easiest gear, and 1-3mm gap between the top of the biggest chainring and the bottom of the deralier cage when shifting into the biggest chainring. if this fails make sure the cage is straight

OliverBendix · *by **OliverBendix** on Sat 5/Jun/10 6:36pm*

Spokes wrote:Are the new rings the same brand as the crank?

Yes, it's a new bike. Should have mentioned that before.

FSR_man wrote:1-3mm gap between the top of the biggest chainring and the bottom of the deralier cage when shifting into the biggest chainring.

This is the problem, I think, as I posted above. The derailleur is too high, but I can't move it down as the end of the cage is just clearing the chainstay in middle/granny. I'm going to the shop tomorrow to replace the cassette that's cracked a cog, and I'll see if a different derailleur will fit the frame design better.

Mr_Bob · *by **Mr_Bob** on Mon 7/Jun/10 7:04pm*

X9 right hand shifters, I've got a customer that's just bought me a bag of shifter parts (they're all there) any tips on rebuilding one? - I've searched around sicklines and pinkbike forums ect....

SlackBoy · *by **SlackBoy** on Mon 7/Jun/10 7:07pm*

Mr_Bob wrote:X9 right hand shifters, I've got a customer that's just bought me a bag of shifter parts (they're all there) any tips on rebuilding one? - I've searched around sicklines and pinkbike forums ect....

hand it back to him and charge him for a new one. Put on the invoice - Stupidity Tax

Bike Mechanics Impart Their Wisdom On Vorb

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