# Why not horizontal dropouts?



## r1Gel (Jan 14, 2004)

Just wondering why the horizontal dropouts of old aren't as prevalent for singlespeed mountain bike frames nowadays? (they're still on road bikes right?) Is there an inherent downside to this dropout design? The current chain tensioning options for SS MTBs that I know of are track ends, sliding drops, or EBBs.

Wouldn't horiz dropouts end the issue of track ends + disc mounts being a pain to use?

My first mountain bike (15 years ago) was steel and had horiz drops, but no disc mounts. I don't see horiz dropouts in currently available (SS-specific or otherwise) bikes anymore. Why is that?


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## perttime (Aug 26, 2005)

Most road bikes have vertical dropouts too. I suspect only some frames that are thought to be used as singlespeed, too, are made with horizontals.

As I see it, the main advantage of vertical dropouts is that the wheel will stay where you put it, no matter what. No issues with the axle or QR slipping in the dropouts.


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## r1Gel (Jan 14, 2004)

perttime said:


> Most road bikes have vertical dropouts too. I suspect only some frames that are thought to be used as singlespeed, too, are made with horizontals.
> 
> As I see it, the main advantage of vertical dropouts is that the wheel will stay where you put it, no matter what. No issues with the axle or QR slipping in the dropouts.


Just edited my original post to specify SS frames.

How come are track ends are more prevalent than horizontal dropouts?

The horiz drops could also employ tensioners (I've seen pics of those, just too lazy to do a search right now...)


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## scooter916 (Jan 2, 2006)

with the design you pictured, if your axle comes loose your wheel will pull out of your frame, with track ends if your axle loosens up it will stay in the bike


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## dbohemian (Mar 25, 2007)

r1Gel said:


> Just edited my original post to specify SS frames.
> 
> How come are track ends are more prevalent than horizontal dropouts?
> 
> The horiz drops could also employ tensioners (I've seen pics of those, just too lazy to do a search right now...)


Basically because its the cool thing to do. Maybe I am old, but people used to use long campy 1010's or any other forward facing long drop and ride a whole season and then move onto cyclocross season all on the same bicycle.

Personally, I dislike rear facing drops, oh, just about for everything. They look right on a traditional track bike but you are correct, a well designed forward facing dropout should work wonderfully on a SS MTB and the only thing I could think of is if your wheel nuts where not tight Then again, your wheelnuts should be tight

Dave Bohm
Bohemian Bicycles


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## Francis Buxton (Apr 2, 2004)

One problem with forward facing horizontals is knobby tire clearance on the chainstays for tire removal/insertion. Basically, you lose some of your short chainstay "shortness" with forward facers. There are ways to work around it for mountain-specific designs (see a dropout design that DWF posted a couple weeks ago). I think track ends seem to simply be the 'easiest' from a frame designer's standpoint, so a vast majority of people moved to them. They are readily available and easy to design around. Like Dave B. and DWF, I'm not a huge fan of them for my own reasons.

I had worked on a design for forward facing horizontals with disc mount but got distracted with other things. Maybe it's time to finish up the design.


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## DeeEight (Jan 13, 2004)

It also makes it hard to get the wheel out past disc brakes... most calipers sit forwards of the axle... pulling the wheel forward could jam the rotor into the caliper. And you have to always be sure the axle is dead perfectly aligned on each side or your wheel won't sit centered.


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## vulture (Jan 13, 2004)

DeeEight said:


> It also makes it hard to get the wheel out past disc brakes... most calipers sit forwards of the axle... pulling the wheel forward could jam the rotor into the caliper. And you have to always be sure the axle is dead perfectly aligned on each side or your wheel won't sit centered.


In practice I have found the opposite to be true. On calipers mounted on the seat stay, with rear entry dropouts one caliper bolt has to be removed to get your wheel out. Some forward facing horizontals use axle location screws which make it easy to get your wheel back to the same place with repeatability. On a rear facing dropout with axle locator screws (paul for example) the wheel has to move forward to release chain tension, remove the wheel and readjust the screws to relocate the wheel. The biggest disadvantage of the forward facing horizontal is chainstay clearance for your tire as mentioned before in this thread. I have been running a fixed cross bike for years with forward horizontals and wheel removal is a snap. Loose axle nuts are a non issue in that if your wheel slips with either dropout you have to stop and fix the problem.


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## dbohemian (Mar 25, 2007)

great explanation wade.

Don had some designs for a forward facing drop that would work great. I have some too that I never made up.

I think one thing to remember is that you only really need slightly more than .5 inch of horizontal movement and if you design your chainstays correctly this should allow one to remove the wheel without hitting the chainstays or bridge.

I do think well designed forward facing drops are technically superior to rear facing generally but lets face it, many things in cycling are not based on solid engineering principles but what is popular at the time. 

I know wade knows all this. I was just putting in my 2c

Dave Bohm
Bohemian Bicycles


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## D.F.L. (Jan 3, 2004)

Most forward-facing horizontals are a little weak because of the minimal amount of material wrapping around the back end of the dropout slot. The wrong bolts, or ham-fisted wrenching, can damage the dropout. Surly used to offer a beefier hooded fwd-facer.

The main problem is that if you show fwd-facing dropouts on the Internets, a bunch of people will bash it, thinking that they'll pull the wheel out. They've never slipped a wheel before, but the mere sight of a fwd-facing slot makes them now believe that they can...


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## DWF (Jan 12, 2004)

D.F.L. said:


> Most forward-facing horizontals are a little weak because of the minimal amount of material wrapping around the back end of the dropout slot. The wrong bolts, or ham-fisted wrenching, can damage the dropout. Surly used to offer a beefier hooded fwd-facer.
> 
> The main problem is that if you show fwd-facing dropouts on the Internets, a bunch of people will bash it, thinking that they'll pull the wheel out. They've never slipped a wheel before, but the mere sight of a fwd-facing slot makes them now believe that they can...


Let them eat cake!


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## seat_boy (May 16, 2006)

This argument seems kind of weak (note I'm not saying you agree with the statement). If you pull the wheel forward with track ends, your riding is pretty much done as your chain just jumped off and you've now hit the stem with your groin. Ouch. Whether your wheel is still attached then or not is kind of pointless.

Moreover, with a forward facing horizontal, some of your mighty pulling force is going into the frame, due to the dropout's angle (vs. a track end, where only the clamping force of the QR or axle bolts is holding it all together).

I ordered a custom frame mostly to get these FFHD, and I might try again in the future when I'm in a downsizing mood (somehow, downsizing my bike fleet always involves buying just one more bike)

Eric
FFHD fan



D.F.L. said:


> The main problem is that if you show fwd-facing dropouts on the Internets, a bunch of people will bash it, thinking that they'll pull the wheel out. They've never slipped a wheel before, but the mere sight of a fwd-facing slot makes them now believe that they can...


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## D.F.L. (Jan 3, 2004)

DWF said:


> Let them eat cake!


Explain these again for us, Don. (just playing the straight-man so he can give everybody the schpeil.) What does the up/forward position do? Seems like it would be the geared position, but is quite forward of the hanger.


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## DWF (Jan 12, 2004)

D.F.L. said:


> Explain these again for us, Don. (just playing the straight-man so he can give everybody the schpeil.) What does the up/forward position do? Seems like it would be the geared position, but is quite forward of the hanger.


Well, the forward position is a ~lock~ position for gearie aps. The way the drawing is tilted makes the d-eye look more rearward than it is, it's actually just shy of 5mm (3/16" to be precise) behind where it is on a Breezer, which as anybody who uses them knows, is actually too far forward for easy tire install/removal when installed "correctly". Basically it's placed where a normal QR/axle nut won't interfere with a rear-D body. The horizontal slot is for SS/FG aps. The fang is mostly emotional/historical, but it does guide the axle/wheel into position.


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## r1Gel (Jan 14, 2004)

I agree. Doesn't the diagonal orientation of the "FFHD" (maybe it should be renamed to "diagonal dropout  ) allow for disc brake caliper clearance? And, while I'm not a frame builder or engineer, I would think the diagonal could be designed in such a way that wheel clearance should be a very minor issue. Being diagonal, removing the rear wheel would be a downward (or upward if the bike is upside down)-and-towards-the-BB movement.
Besides, can't the slotted disc caliper mounts be employed for diagonals as well, to allow for more precise caliper-rotor alignment?
And, as seat_boy mentioned below, the fear of pulling the rear wheel out on a FFHD is unfounded as some of the force goes into the frame since the dropout isn't horizontal at all. In any case, my first MTB was a steel hardtail with a FFHD, and I never experienced any slippage. And I was using QRs!



vulture said:


> In practice I have found the opposite to be true. On calipers mounted on the seat stay, with rear entry dropouts one caliper bolt has to be removed to get your wheel out. Some forward facing horizontals use axle location screws which make it easy to get your wheel back to the same place with repeatability. On a rear facing dropout with axle locator screws (paul for example) the wheel has to move forward to release chain tension, remove the wheel and readjust the screws to relocate the wheel. The biggest disadvantage of the forward facing horizontal is chainstay clearance for your tire as mentioned before in this thread. I have been running a fixed cross bike for years with forward horizontals and wheel removal is a snap. Loose axle nuts are a non issue in that if your wheel slips with either dropout you have to stop and fix the problem.


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## BeatAFool (Jan 14, 2008)

I still prefer vert. drops and either a Eno hub or a chain dangler. I'm not too interrested in fads just what works.


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## ernestrome (Aug 1, 2008)

BeatAFool said:


> I'm not too interrested in fads just what works.


Yet you ride a singlespeed...


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## Claysaddiction (Mar 27, 2009)

BeatAFool said:


> I still prefer vert. drops and either a Eno hub or a chain dangler. I'm not too interrested in fads just what works.


good to find someone who prefers what works over fad these days
i would also prefer what works best too


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## BeatAFool (Jan 14, 2008)

> Yet you ride a singlespeed...


Yes........ my Zoo Pitbull is a ss with a dangler. If it works in trials, I'm sure it'll work for your tready mtb.


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