If I Buy A New Rear Mech Hanger, Does It Need Re alingnment?

[gbb]

It's worth remembering, if you have a bent hanger, it can be worth trying to bend it back yourself,
My ebike got clattered and it had a quite obvious mis alignment of the dearilleur. Looked at which way I needed to bend the hanger, derailleur off, used an adjustable spanner and manipulated the hanger back. Two goes and I've been riding it ever since. No it's not 100% but it's perfectly good.

 

[screenman]

It's worth remembering, if you have a bent hanger, it can be worth trying to bend it back yourself,
My ebike got clattered and it had a quite obvious mis alignment of the dearilleur. Looked at which way I needed to bend the hanger, derailleur off, used an adjustable spanner and manipulated the hanger back. Two goes and I've been riding it ever since. No it's not 100% but it's perfectly good.

Not 100% and perfect? I know what you are getting at but for the sake of a fiver at your lbs why not get it right.

 

[screenman]

Brand spanking new last Saturday.

Means nothing if it is a cheap one.

 

[gbb]

Not 100% and perfect? I know what you are getting at but for the sake of a fiver at your lbs why not get it right.

And that's quite right, but some of us like to pull up our sleeves and have a go.

 

[gbb]

Lots of free wheels do wobble, that's not unusual but a snapped or bent axle should also be checked for.

 

[screenman]

And that's quite right, but some of us like to pull up our sleeves and have a go.

That sounds like me, thing is I have the right tools to do that job, just different standards I guess nothing wrong with that,

 

[Lovacott]

Means nothing if it is a cheap one.

It was a direct like for like replacement for the old one. Shimano MF-TZ21 7 Speed Bike Screw-On Freewheel.

 

[screenman]

It was a direct like for like replacement for the old one. Shimano MF-TZ21 7 Speed Bike Screw-On Freewheel.

You have to go a long way up the price scale to get precision engineering, that said you can do a lot of miles on lower priced equipment as well.

 

[Ajax Bay]

Imo the chances of a 7sp freewheel being off is low (compared to a freehub/cassette).
The influence of the chain on the sprocket has nothing to do with rear mech alignment (RMA)(which needs to be right for successful indexing/shifting @screenman ). Except when the line of the chain is directly fore/aft, the chain in tension (at the top) will pull the sprocket laterally very slightly and on release the sprocket will 'wobble' back to neutral equilibrium position. This lateral force and removal thereof will affect the whole cassette/block. This is normal and has no adverse effect on the drivetrain or shifting. If things (chainline) are set up correctly the middle ring will be directly in line with the middle sprocket. Find that @Lovacott and see if there's less wobble.
Provided the indexing is accurate, there will be no such effect at the bottom of the sprocket as the guide pulley wheel will be correctly aligned (so poor RMA is not a causative issue).
By the way and off topic, despite the poor press cross-chaining has, drivetrain losses are less with cross-chaining than the gain in efficiency you get by opting for a larger chainring and a larger sprocket (reference available - and shared a fair while ago). So 'keeping it in the big ring' has a basis in science. Warning: this will not stop grumpy over-sharing pedants offering advice from behind as they gratuitously suck your wheel and have ample opportunity to examine your cross-chaining heresy.

 

[Lovacott]

If things (chainline) are set up correctly the middle ring will be directly in line with the middle sprocket. Find that @Lovacott and see if there's less wobble.

As you suggested above, I've just checked and there is no wobble at all. Gears change sweetly and I get no noise at all with the crossover gears.

 

[Lovacott]

By the way and off topic, despite the poor press cross-chaining has, drivetrain losses are less with cross-chaining than the gain in efficiency you get by opting for a larger chainring and a larger sprocket (reference available - and shared a fair while ago).

There is one hill I cross my chain on which I wouldn't do in any other way.

I go small on the front and small on the back as I turn right on a hump back bridge and up along a 10% hill which gets to 30% near the peak.

I know I will need the small chain ring near the peak but I avoid shifting down on the front when under load so I select my front chain ring well beforehand.

I then use the freewheel gears to adapt to the different parts of the hill.

 

[cyclintom]

yep a new hanger needs aligning after fitting it.

If you buy the proper hanger for your frame and you install it properly it should put the rear derailleur in the proper position. You don't go bending aluminum or carbon fiber bike hangers around since that can fatigue the one frame and break the other. Steel frames lend themselves to realignment without any negative side effects. Because of the unreliability of both aluminum and carbon fiber frames and the present weight limit being at or very near that which can be met with steel frames I would predict that we will be seeing steel bikes return since there have been so many carbon frame failures. The power that a pro-level sprinter can produce is nothing less than phenomenal at perhaps 1800-2000 watts in a sprint with CF bike designed for the 400-450 watts produced over long periods of time by the peloton.

 

[raleighnut]

If you buy the proper hanger for your frame and you install it properly it should put the rear derailleur in the proper position. You don't go bending aluminum or carbon fiber bike hangers around since that can fatigue the one frame and break the other. Steel frames lend themselves to realignment without any negative side effects. Because of the unreliability of both aluminum and carbon fiber frames and the present weight limit being at or very near that which can be met with steel frames I would predict that we will be seeing steel bikes return since there have been so many carbon frame failures. The power that a pro-level sprinter can produce is nothing less than phenomenal at perhaps 1800-2000 watts in a sprint with CF bike designed for the 400-450 watts produced over long periods of time by the peloton.

The hanger is designed to bend, and also to snap off before the frame is compromised. any new hanger plate should be checked for alignment and corrected if 'out'

As for Aluminium not bending I take it you didn't watch this,

View: https://youtu.be/icWIGDHl6sA

 

[screenman]

If you buy the proper hanger for your frame and you install it properly it should put the rear derailleur in the proper position. You don't go bending aluminum or carbon fiber bike hangers around since that can fatigue the one frame and break the other. Steel frames lend themselves to realignment without any negative side effects. Because of the unreliability of both aluminum and carbon fiber frames and the present weight limit being at or very near that which can be met with steel frames I would predict that we will be seeing steel bikes return since there have been so many carbon frame failures. The power that a pro-level sprinter can produce is nothing less than phenomenal at perhaps 1800-2000 watts in a sprint with CF bike designed for the 400-450 watts produced over long periods of time by the peloton.

I bend aluminium for a living, you will not bend the frame by adjusting the hanger. Tell us with all your expertise why they make very lightweight stunt planes using carbon fibre.

 

[Ajax Bay]

If you buy the proper hanger for your frame and you install it properly it should put the rear derailleur in the proper position. [1] You don't go bending aluminum or carbon fiber bike hangers [2] around [3] since that can fatigue the one frame and break the other. Steel frames lend themselves to realignment without any negative side effects. Because of the unreliability of both aluminum and carbon fiber frames [4] and the present weight limit being at or very near that which can be met with steel frames [5] I would predict that we will be seeing steel bikes return since there have been so many carbon frame failures. The power that a pro-level sprinter can produce is nothing less than phenomenal at perhaps 1800-2000 watts in a sprint with CF bike designed for the 400-450 watts [6] produced over long periods of time by the peloton [7].

@cyclintom - You're an engineer so the few questions/requests embedded in the observations below will be easy for you to answer:
1) Should: yes. But if you can't get the indexing to work, suspect poor alignment and check.
2) Edit: I think you must mean hangers on aluminium and carbon fibre bikes
3) Bending very small amounts/angles and ideally once only of an aluminium hanger will not mean the hanger is significantly weaker. Edit: How could bending a hanger attached to an aluminium-framed bike drop out possibly 'fatigue' the frame? You understand the mechanisms of fatigue, right, as opposed to deformation beyond elastic?
4) On the 'reliability' spectrum, it's unreasonable to describe either carbon or aluminium frames as unreliable.
5) I suggest that a steel bike constructed to meet the UCI weight limit (with disc brakes surely, and that 'unreliable' carbon fork, I assume) will itself be as vulnerable to failure as a bike made of different material.
6) Please share with us an example of a CF framed bike which is "designed for 450w" (you imply it is liable to failure above its design spec).
7) Well perhaps the uber sprinters need a bike specially designed for them to cope with this spike of power ([Spoiler/] they don't).

Disclosure: Getting on for a million km (well closer to one million than none ) on my current steel bike.