OK now. I got my first flat on my new road bike and had to take the wheel off to change the tube. My old bike was a mountain bike with vertical dropouts. So putting the wheel back in was simple, as gravity holds it in the correct position. New bike has horizontal dropouts which I didn't really think about before. I got the wheel back in fine and put it into the dropout as far as it would go and tightened it up. But wouldn't the position in the dropout influence how right the chain becomes and hence other factors?

Did I do the right thing?

Logic also says to me that with horizontal dropouts you need to be more careful with making sure you tighten the wheel back on nice and firm.

What are the advantages of hoizontal dropouts again?

Most road bikes have small screw adjusters that determine how far back the hub can go. If you have those then push the hub as far back as it can go and tighten there. Yes it does affect the chain tension to some degree and also affects the alignment of the wheel in the frame. If you don't have the adjusters you still should push it back as far as you can but make sure the wheel is straight in the frame before you tighten the lock.

I've no idea why the dropouts are horizontal. As someone who is pretty good at ripping back wheels out of them I sometimes wish they weren't.

Horizontal dropouts were around before vertical drops, and they allowed much looser production tolerances. They also allow for correct chain tensioning on one-speed and internal-hub gear bikes, which used to be much more popular before the advent of cheap, reliable derailleur systems.

When replacing the wheel on a derailleur-equipped bike with horizontal dropouts, you should try to place the axle directly above the derailleur mount. Exact positioning normally isn't super-critical.

With long horizontal dropouts, you do want to make sure that you have a set-screw or some other method of replacing the wheel to the same place or your brake alignment will be off. If you've adjusted a pair of rim brakes with the wheel in a forward position in the dropout, then move the wheel all the way back in the dropout, it's possible the brakes may cut the sidewall of the tire.

regarding the kind or horizontal dropouts where the wheel is removed by pulling it forward out of the dropouts, only:

I always found these horizontal dropouts easy to use, but i might think differently if I didn't use this process to put a wheel in:

1. put the axle in, and push the right side of the axle as far back as it will go, keeping the wheel reasonably straight. Tighten down the right axle nut, making sure the right side of the axle doesn't slip forward. don't make it super-tight.
2. tighten the left side of the axle; use one hand on the rim/tire to keep the wheel straight at the same time. look at the chainstays to verify that the wheel is reasonably straight.
3. tighten the right axle nut again, making sure not to change the axle position - the axle nut has to be tight enough to keep all of the force you put on the chain from pulling the axle out of position... don't break the axle nut though.
4. if this is your first time using this process on a particular bike, look at the brakes. if necessary, reposition the brake pads so they'll contact the rim properly.

.

I recommend the above process as a quick & easy way to put a wheel in.

On most horizontal dropouts, pulling the axle all the way back in the slot will result in poor positioning of the derailleur in relation to the freewheel. As I said before, the axle should be positioned directly above the main derailleur ("B") pivot.

Like this (yeah, it's a vertical dropout):



Not like this:

Yup, I beleive thats the reason most clamp on derailuers lock out part of the drop out so the wheel naturaly falls there. I've even been noticing dept store bikes (schwinns in the cases I've seen) where the drive side dropout doesn't run as far back (a really stupid system imo but much cheaper than getting good enough facilities for tighter tolerances alowing vertical dropouts)

That rear derailleur housing loop is also too short.

Yeah, my semi-old Schwinn LeTour has a blocked-off dropout like that:
https://home.comcast.net/~jeff_wills/...es/bike033.htm
Thankfully, it didn't prevent me from setting the bike up as a single-speed. I've since upgraded it to 7-speed with a Dura-Ace AX hub and a Ultegra derailleur.

Well thank Ghu it's not my bike!

It gave me alot of trouble setting up my friends bike as a singlespeed, I never could get the chain tension right but the chainline was good so theres never been any problems, maybe I'll file it out just a bit one of these days... or not as I'm building a new bike to replace the one I'm thinking about.

Probably didn't help that I was doing the conversion in the dark and it took me a good 5 minutes to even notice what was going on

Is this a 'new' new road bike with horizontal dropouts? Isn't that pretty unusual?

A little uncommon would be more accurate imho.

These fit most frames and make repeatable tensioning/positioning easy. I use them on my singlespeed moutain bike that has horizontal dropouts.

https://surlybikes.com/parts/tuggnut/