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

[woodbine]

Just wondering what these adjustment screws are on the rear wheel axle mountings (are they called hangers?? ) - and what purpose they serve. What play or wear do they compensate for? When should they be adjusted - eg. new chain? Is it best to have them screwed all the way in, all the way out, or half way?

Just a bit confused as to their purpose, as I don't recall owning another bike with these, or even seeing other bikes with them fitted.

 

[Levo-Lon]

Wheel alignment..it looks like a moddification by someone..but its on most if not all motorcycles and allows acurate wheel setting..

but it seems over kill on a bike..

 

[Citius]

Drop out adjusters. They do what it looks like they do - they give you the choice of where you want the wheel to sit in horizontal dropouts. I have mine sitting near the forward end.

 

[woodbine]

Thanks for your replies. Just wondered why most bikes don't seem to have them.

Citius.>>>>> I think I may know the answer to this, but is there any reason yours are positioned to the front? Is there any advantage, or does it make any difference to how the derailleur operates?

 

[Citius]

Horizontal dropouts have been pretty much superceded by vertical dropouts, especially for bikes with multi-speed freewheels. I have my wheel sitting near the front end of the dropout as it is marginally easier to remove the wheel, no other reason.

You tend not to see horiziontal dropouts on new frames these days - except maybe on some 'retro' handbuilts, if the buyer specifies them - not to be confused with track ends, which are open ended at the back (and are also 'properly' horizontal).

 

[nikintheuk]

You will find them on all top end bikes of the old Super Record/ Nuevo Record Era, around '85 and earlier. The campagnolo drop outs of that era all came pre-threaded. They are not so important for day to day cycling, but during a race allow for a mechanic to very quickly fit a wheel and know it is centered between the stays.

 

[snailracer]

They are for adjusting chain tension on single-speed and fixed-gear bicycles, which is done by shunting the rear wheel further backwards or forwards in the horizontal dropout slot using the adjuster screws.

Chain tension on a derailleur bike is automatically adjusted by the spring on the derailleur arm, so these bikes have a vertical dropout slot with no adjuster screws. The advantage of the vertical dropout slot is that high chain tension will not cause the wheel to slip forward.

 

[jonny jeez]

Should you ever want to sell that frame, to someone interested in single speed riding, I would imagine those chain adjusters will prove to be an attractive feature.

 

[raleighnut]

The stops do not tension the chain (they're on the wrong side of the axle for that)
They are simply there to allow a wheel to be centred when fitting in a hurry as @nikintheuk rightly posted earlier.

 

[Citius]

They are for adjusting chain tension on single-speed and fixed-gear bicycles, which is done by shunting the rear wheel further backwards or forwards in the horizontal dropout slot using the adjuster screws.

Sorry, that's completely incorrect. Those are not 'single speed' or 'fixed' dropouts - because such bikes will have horizontal track ends, as mentioned previously. Those droupouts were commonplace on steel frames up until the early 90s - you can even see the derailleur hanger in the background of the pic.

You can also use them for a single speed conversion, as many do. But that was not their intended purpose and the pic is evidence of that.

 

[biggs682]

normally found on decent quality and above frames

and i believe its to allow as others have stated for easier wheel changes as if set right wheel should align up in rear frame without having to pull to one side but i could be wrong

 

[snailracer]

Sorry, that's completely incorrect. Those are not 'single speed' or 'fixed' dropouts - because such bikes will have horizontal track ends, as mentioned previously. Those droupouts were commonplace on steel frames up until the early 90s - you can even see the derailleur hanger in the background of the pic.

You can also use them for a single speed conversion, as many do. But that was not their intended purpose and the pic is evidence of that.

It is true that horizontal "track ends" face backwards on track bikes. This may be because track bikes are so short that there is no space for the rear wheel to slide forward, but more likely because they were simply designed that way in the distant past.

On road-oriented fixed/SS bikes, horizontal dropouts deliberately face forwards. This is so that the rear wheel can be removed quickly for puncture repairs, as sliding forward disengages the chain at the same time. Adjuster screws enable the wheel to be refitted quickly in exactly the same place, with same chain tension and accurately aligned as before. Adjuster screws are rarely designed into track bikes because they rarely puncture, and if they did there is no hurry to fix them because you're already out of the race.

There is no reason why a road bike cannot have both horizontal dropouts AND a derailleur, that results in a versatile frame which is what appears in the OP's photo. Such dual-use bikes were common during the 70's, where it was the fashion to ride geared in the summer/while racing, and fixed/SS during winter training.

 

[snailracer]

The stops do not tension the chain (they're on the wrong side of the axle for that)
They are simply there to allow a wheel to be centred when fitting in a hurry as @nikintheuk rightly posted earlier.

The photo shows that the adjuster screws are on both sides of the axle.
For fixed/SS, chain tension is set by positioning of the axle. Maybe I was unclear about that, the adjuster screws carry no forces whatsoever, nonetheless they position the axle and therefore, indirectly, tension the chain. They also align the wheel, which is a bonus.

 

[raleighnut]

The photo shows that the adjuster screws are on both sides of the axle.
For fixed/SS, chain tension is set by positioning of the axle. Maybe I was unclear about that, the adjuster screws carry no forces whatsoever, nonetheless they position the axle and therefore, indirectly, tension the chain. They also align the wheel, which is a bonus.

Maybe I wasn't clear, the adjusters (properly named axle stops) are at the rear of the axle (the wrong side) so do not prevent the axle being pulled forwards by the chain like a tensioner would (as found on Motorcycles, BMX bikes and some track bikes)

 

[snailracer]

Maybe I wasn't clear, the adjusters (properly named axle stops) are at the rear of the axle (the wrong side) so do not prevent the axle being pulled forwards by the chain like a tensioner would (as found on Motorcycles, BMX bikes and some track bikes)

On bicycles with forward-facing horizontal dropouts, the adjuster screws are only there to accurately position the axle - the axle nuts have to be strongly tightened to stop the axle being pulled forward by chain tension. This is why vertical dropouts exist: a quick-release skewer is not as strong as axle nuts, and so the axle would be pulled forward if the dropouts weren't vertical.