from Rookie’s keyboard
Hello, friends
Today, I will dissect horizontal and vertical dropouts. The short story is that vertical dropouts are the overall winner for most people, especially rookies. I am not saying that horizontal dropouts don’t have their place, but their niche is simply smaller.
The basic pros and overall feature of horizontal dropouts (HDs) are:
- Ideal For Single-speed and Fixed-gear Projects
The strongest pro of HDs is that you can slide the rear wheel forward and back.
Thus, it’s possible to increase or decrease the chain tension by changing the wheel’s position.
HDs are therefore a necessity for bicycles with one gear because those do not have a derailleur to tension the chain.
(Note: The only exception are one-speed bicycles that use a dedicated chain tensioner.)
- Seat Tube Clearance
HDs allow you to move the rear wheel ever so slightly away from the seat tube.
This option is beneficial for frames that have a tight rear wheel clearance and/or a cutout in the seat tube for the rear wheel.
If you change your rear tire, the new one may inflate to a greater volume than the previous one (even if they’re both the same size) and get too close to the seat tube. In that case, you can can slide the wheel backward to increase the clearance.
Meanwhile, if you switch from wide to narrow tires, there may be a needlessly large gap between the tire and the seat tube.
- Shorter Effective Chainstay Length
I forgot to mention that there are two versions of horizontal dropouts – rear and forward facing.
Nowadays rear-facing dropouts (the first image) are the more popular version.
They allow you to remove the wheel by pulling it back and away from the frame.
As a result, the frame can have shorter chainstays.
Forward-facing dropouts were the norm back in the days of steel road bikes. At the time, the frames had longer chainstays and it was possible to remove the rear wheel by sliding it forward and down. Today, this isn’t the case.
The position of the wheel affects effective chainstay length. By pushing the wheel closer to the seat tube, one is effectively shortening the chainstays because the axle which is the pivot point is getting closer to the bottom bracket.
That said, vertical dropouts (VDs) allow the use of very short chainstays too because the wheel moves vertically when removing and installing it.
What vertical dropouts don’t offer, however, is precise adjustment. They have a preset setting for the axle’s position which cannot be changed.
And now the downsides….
- Quick-release Skewers Could Be An Issue
HDs receive criticism when paired with a quick-release skewer.
The main predicament is that the skewer could fail to squeeze the dropouts sufficiently and the rear wheel could slide forward. The result is an uneven position and inadequate chain tension.
This more likely to happen when riding up a very steep hill and generating lots of torque.
The solution is to increase the friction between the quick-release and the dropouts.
Normally, the sides of the quick-release ends that come in contact with the dropouts are serrated.
The outer part of the hub’s locknut should also be serrated. If the areа is clean (no grease, dirt…etc.) the grip is often sufficient as long as the serrations are present.
Some people go a bit more extreme and even remove the paint on the dropout contact area to maximize friction.
This procedure has a downside – the area can corrode due to the absence of paint. Truth be told, however, if the ends and the locknuts are serrated, they will chew up the paint anyway.
This slippage issue is a lot more common for aluminum frames because the material is softer.
When you pedal hard, the chain could pull the rear wheel forward causing the quick-release ends to cut material from the dropouts over time.
Another solution to this problem is to switch to solid-axle hubs secured to the wheel via nuts. Nutted axles offer a superior clamping power to quick-release skewers. Hence track bikes continue to use solid-axles with nuts to this day.
- Rear Wheel Removal Is Trickier
In the case of forward-facing HDs, the chainstay bridge may prevent you from removing the wheel without deflating the tire. This is a common scenario for retro road bikes. The problem is more pronounced when running the maximum tire size that the frame can accommodate.
If the dropouts are rear-facing, the problem mentioned above is not present, but the removal of the rear wheel is still trickier than it is with vertical dropouts.
When the dropouts are vertical, the rear wheel will drop out as soon as you undo the quick-release and press the derailleur forward to create chain slack.
With rear-facing dropouts, you have to pull the wheel back and out, and if you’re not familiar with the proper technique, the process can be a bit annoying.
And if the bike has disc brakes, you may also have to loosen the caliper bolts to get the wheel out.
This is a common for bikes that have the caliper mounted on the seat stay. If the caliper is on the chainstay, the wheel should slide out without having to untighten the caliper bolts.
For the reasons above, if the bike is meant to have gears, vertical dropouts are the most logical choice as they save time and lots of tinkering.
Here are all their pros:
- Pre-determined Wheel Position
Vertical dropouts do not give the axle room to move. The wheel goes to the same bed, and you don’t have to adjust its horizontal position (apart from some lateral thinkering).
- Quick Release Skewers Always Hold
The quick-release skewers do not have to fight a wheel that wants to go forward. As a result, it takes less clamping force to keep the wheel in place.
- Simple Wheel Removal
To remove the rear wheel, you have to shift to the smallest sprocket at the back as well as to the smallest chainring, undo the quick release, and push the derailleur forward. Then, the wheel will drop out right away.
Some minor downsides…
- Chain Tensioners Are Needed For Single Speed
If you want a single-speed set-up on a bike with VDs, you will need a dedicated chain tensioner.
Another option would be to keep the rear derailleur which also serves as a chain tensioner.
- Reduced Control
VDs do not allow the rider to increase or decrease the space between the rear wheel and the seat tube. In some situations, this could result in poor clearance.
Removable Dropouts – The Best of Both Worlds?
Some frames allow you to remove the dropouts and switch from vertical to horizontal or vise versa. However, those models are usually pricy and therefore not rookie friendly.
Until next time,
Rookie
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