What Are These Adjustment Screws On Wheel Mountings (Hangers??) For?

[Citius]

I wonder if the pic in the OP is of an incomplete version of one of these:

http://en.hollandbikeshop.com/brand...ioner/batavus-chain-tensioner-45mm-bolt-30mm/

No, it isn't. It is simply a pic of good ol' fashioned horizontal dropouts, ffs.

 

[Citius]

I don't think so. Such frames have been designed to so that you can use them either fixed/SS or derailleur. One modern example from the Surly website:

"Rear Dropouts
Semi-horizontal dropouts give you singlespeed compatibility and wheelbase adjustability. Adjuster screws are included to keep your wheel in the right place for optimal shifting if you go with derailleurs."

http://surlybikes.com/bikes/cross_check/frame_highlights

Like I already said, you can use any dropout for that. And like I already said (again) - your assertion that they are intended for single speed use is incorrect. The mech hanger on the r/h dropout is evidence of that - if any were needed.

 

[snailracer]

Like I already said, you can use any dropout for that. And like I already said (again) - your assertion that they are intended for single speed use is incorrect. The mech hanger on the r/h dropout is evidence of that - if any were needed.

The Surly is intended for fixed/SS or derailleur and is advertised as such. Sure, the mech hanger can be used to mount a chain tensioner, but the Surly doesn't need that to run fixed/SS because it has horizontal adjustment, and some people prefer that.

 

[snailracer]

Chain tension on a derailleur-geared bike is taken care of by the spring on the jockey wheel cage. - it is not something you would need to adjust at the dropouts. Such an adjustment would have no effect anyway.




The frame I am referring to was built specifically for road/racing. By someone that knew what they were doing.

Citius = youngoldbloke??

 

[Citius]

Surly didn't even exist when builders started using those dropouts, so I don't understand why you are clinging to that scrap of info as proof you are not wrong?

And just because two different people happen to disagree with you on the internet - doesn't mean it is two accounts used by the same person. It just means that two different people think you are wrong.

 

[Poacher]

Make that three!
(and a clue: I'm neither Citius nor Youngoldbloke)

 

[snailracer]

Surly didn't even exist when builders started using those dropouts, so I don't understand why you are clinging to that scrap of info as proof you are not wrong?

Are you saying I was wrong in the 1970's, but I'm right now?

...And just because two different people happen to disagree with you on the internet - doesn't mean it is two accounts used by the same person. It just means that two different people think you are wrong.

I was just curious about why you appeared to reply on youngoldbloke's behalf. He's talking about his bicycle, and you're saying it's your bicycle .
I'm not even close to getting steamed up about this, no need for you to be, either. I take the view that if there's disagreement, then discussion continues.

 

[Citius]

I'm talking about my own frame, which was built with horizontal dropouts in 1993. It was (and still is) a road bike intended for derailleur use. Seriously though, you've got to let go of this fixed/ss nonsense.

 

[youngoldbloke]

Frame makers have no problem accurately placing dropouts. However, the ability to position the axle in different positions along the slot enables chain tension to be accurately maintained as the chain and chainset wears. This function is performed by an eccentric bottom bracket on a SS/fixed/hub geared bike with vertical dropouts.

Well this is making me nostalgic.

Did your bike have the ability to run either fixed/SS or derailleur?

The Adjusters had nothing to do with chain tension. Of course I could have taken the rear mech off and and used the bike as single speed/fixed if I had wanted to ( I had another fixed wheel bike for winter training) but the drop out adjusters would have performed no different function to that as when set up as a geared bike - they controlled the REARWARD movement of the back axle in the drop out slots - nothing to do with the accuracy of the dropouts - they simply allowed you to set the position of the rear wheel so that you could easily replace it. IF you put a fixed wheel into those dropouts the pressure from the chain would pull the wheel FORWARDS, away from the adjusters. They had no effect on that whatsoever, other than allowing you to push the axle back to the position it HAD been in before it was pulled forward!

 

[ayceejay]

Incidentally, I believe the dropout as shown in the OP was a feature of frames built during a certain period using Columbus tubing.

 

[snailracer]

Here is a horizontal dropout. Indisputably fixed/SS:

Here are some horizontal dropouts with derailleur hangers, with and without adjuster screws.

Are these somehow unsuitable for fixed/SS use? Does adding a derailleur hanger make the horizontal dropout unusable for fixed/SS, or only usable with a chain tensioner? Obviously not, and I see no reason why a frame maker would suggest otherwise. Besides, who can claim to know the exact intentions of every frame maker of that era?

The derailleur came into common use during the 70's, in a time when most bike frames had horizontal dropouts for use with fixed/SS/hubgears. It was a selling point for new frames to be backwards-compatible with old wheels, which is why so many frames in the 70's were (and some still are) designed for both derailleur and fixed/SS/hubgears.

 

[Poacher]

Here is a horizontal dropout. Indisputably fixed/SS:

Here are some horizontal dropouts with derailleur hangers, with and without adjuster screws.

Are these somehow unsuitable for fixed/SS use? Does adding a derailleur hanger make the horizontal dropout unusable for fixed/SS, or only usable with a chain tensioner? Obviously not, and I see no reason why a frame maker would suggest otherwise. Besides, who can claim to know the exact intentions of every frame maker of that era?

The derailleur came into common use during the 70's, in a time when most bike frames had horizontal dropouts for use with fixed/SS/hubgears. It was a selling point for new frames to be backwards-compatible with old wheels, which is why so many frames in the 70's were (and some still are) designed for both derailleur and fixed/SS/hubgears.

Well, I'll dispute it. Many frames, generally cheaper ones, were built like this for derailleur use. See Sheldon's site, look at the Hanger vs Frame Mount illustrations.
The fact that they could be used for fixed, even though they were far from ideal for this, does not mean that they were intended for this purpose.
Just let it go, for Pete's sake.

 

[youngoldbloke]

Here is a horizontal dropout. Indisputably fixed/SS:

Here are some horizontal dropouts with derailleur hangers, with and without adjuster screws.

Are these somehow unsuitable for fixed/SS use? Does adding a derailleur hanger make the horizontal dropout unusable for fixed/SS, or only usable with a chain tensioner? Obviously not, and I see no reason why a frame maker would suggest otherwise. Besides, who can claim to know the exact intentions of every frame maker of that era?

The derailleur came into common use during the 70's, in a time when most bike frames had horizontal dropouts for use with fixed/SS/hubgears. It was a selling point for new frames to be backwards-compatible with old wheels, which is why so many frames in the 70's were (and some still are) designed for both derailleur and fixed/SS/hubgears.

That is NOT a 'Indisputably fixed/SS' dropout. It is simply the cheap pressed steel dropout used on most bikes until vertical dropouts were introduced. A cheap bolt-on derailleur hanger was/is used to attach a derailleur mech. Also used with Sturmey Archer and single speed freewheels. It was and is desirable to use rearward facing fork ends ( 'track ends') with fixed wheels due to the constant forward pull from the transmission. The two below are forged dropouts, fitted to more expensive road bike frames. To be accurate they are sloping dropouts, not horizontal.

 

[snailracer]

The Adjusters had nothing to do with chain tension. Of course I could have taken the rear mech off and and used the bike as single speed/fixed if I had wanted to ( I had another fixed wheel bike for winter training) but the drop out adjusters would have performed no different function to that as when set up as a geared bike - they controlled the REARWARD movement of the back axle in the drop out slots - nothing to do with the accuracy of the dropouts - they simply allowed you to set the position of the rear wheel so that you could easily replace it. IF you put a fixed wheel into those dropouts the pressure from the chain would pull the wheel FORWARDS, away from the adjusters. They had no effect on that whatsoever, other than allowing you to push the axle back to the position it HAD been in before it was pulled forward!

The screws make wheel replacement faster, but that, in principle, could also be done by accurately locating the closed end of the dropout.

The screws are screws because they can fine-adjust the axle location backwards and forwards. This is necessary to accommodate different gearing (as well as mechanical wear). Changing the number of teeth on the rear sprocket or chainring alters the required chain length, and because chain lengths can only be selected in fairly coarse, 1/2 inch increments, adjustment in the rear-axle-to-bottom-bracket separation is needed in order to maintain chain tension/avoid chain droop.

 

[youngoldbloke]

BTW 'real' race bikes had forged dropouts without the mudguard eyes.