What's the reason for having horizontal droputs on fixed & SS bike frames? Is it just so you have some way to adjust chain tension (which would otherwise be controlled via derailleur adjustment on a geared bike), or is there some other explanation?

Just wonderin'.

Horizontal dropouts or track ends?

And I think you answered you own question.

"Is it just so you have some way to adjust chain tension"

yes.

just for clarification, most of the bikes here have track ends (open backwards). horizontal dropouts are the older style that open forward but are longer.
https://www.sheldonbrown.com/singlespeed.html

yup

I'm pretty sure that track ends are much older, maybe someone else can confirm this. In my understanding (forward facing) drop-outs were invented so that you could get the wheel off without derailing the chain, i.e. drop the wheel out of the chain loop.

Can anyone give a more specific timeline or correct me if I'm wrong here?

If you want to get hard-core technical, the oldest bikes were closer to track ends than horizontal dropouts.

But odds are, if you see a bike on the street, and it's got horizontal dropouts, it's not new.

My mistake, I thought the guy was saying that (h.) dropouts are older than track ends, as if track ends were an innovation of some clever person who was unsatisfied with drop outs.

I had the impression that the rear entry fork ends were in case the wheel slipped you wouldn't lose it and crash. Makes sense on a track bike where you're putting enormous energy into a sprint say, or a bmx with tricks and jumps and stuff. Maybe I just made that up.

And they look cool, almost as cool as a horizontal dropout conversion bike.

I think we to go back to the Draisienne. Seriously awesome.

AFAIK this has been debunked by armchair analysis on this forum though perhaps it may be a possibility. The idea is, if one of your track nuts or dropouts fails, the other one will still be there to hold on regardless of which direction the dropout is facing. So your axle will slide back, and your wheel will go into the chainstay (but not fall off) and you will go into a skid, whether you have track ends or not.

It seems to me like track ends are just the most bone simple way to mount a rear wheel on a ss bike that allows for adjustable chain tension, and that's why they are the oldest and still frequently used. But I'm far from certain so I would appreciate it if someone who knows what they're talking about would pipe in.

Sounds cool and all, but when you actaully look at the forces applied, derailleur bikes apply way way way more torque and force to the rear axle/etc than ANY single geared bike, regardless of rider's strength or ability.

And if the wheel slips on either a bike with horizontal dropouts or a bike with track ends, the wheel end up in the same place: locked against the non-drive side chainstay, sending you into a uncontrollable skid.


Horizontal dropouts are actually way better and more functional than track ends.

Yeah, I think that actually makes more sense. I've even had that happen with a broken QR on a derailleur bike with horizontal drops, and that's exactly what happened - wheel hit the non-drive chainstay and I skidded, all confused.

I've always been on the horizontal dropouts are better functionally than track ends tip though.

Horizontal dropouts are only more functional with a rear brake so you never have to re-adjust the pads when changing chain tension.

How does a RD put more force on the axle? Because of the mechanical advantage of the gearing? I don't follow if that's why.

edit.

my ascii art didn't work... a geared bike will have the rear wheel dished while a proper track/ss wheel will be dished to center....



I ended up bending a couple axles when I converted to ss/fixed with a wheel like the one to the right.

Rear brake adjustment, if you ever want to run full fenders without hassle, versatility.

Track ends are only really useful if you want to jam the rear wheel 1/8" from the seat tube.

It's not the RD, it's the gearing that puts force on the chain/axle. Lower gears=more torque/force.

A weak 110# person spinning in a granny gear will generate more torque/force on the chain and on the qr/axle than any world champion track rider. This is why QRs can be used on fixed rear wheels- they are under way higher loads on geared bikes. Same thing with chains- they are under way higher stresses on geared bikes than on any fixed bike.