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Below you will find the main properties of sliding dropouts as well as the issues associated with this style of frame engineering.

Definitions

Dropouts. The parts of the frame/fork to which the front and rear axle attach via bolts, quick-release skewers, or thru-axles.

Sliding dropouts. Dropouts with a mechanism that allows the user to adjust their horizontal position.

Effective Chainstay Length

The main advantage of sliding dropouts is that they allow the user to adjust the effective length of the chainstays via the sliding mechanism.

• By positioning the dropout closer to the front wheel, the user shortens the effective chainstay length.

• By moving the dropouts away from the front wheel, the user maximizes the effective chainstay length.

A longer chainstay increases the wheelbase (the distance between the front and rear axle) and makes the bike more stable and better at climbing. Those changes happen at the expense of cornering and overall maneuverability.

Shorter chainstays offer snappier handling and facilitate the lifting of the front wheel – a beneficial property when performing tricks such as bunny hops and manuals on the rear wheel.

In short, sliding dropouts allow you to switch between aggressiveness and efficiency with ease.

Single-speed Friendly

Another advantage of sliding dropouts is the ability to tension the chain without a derailleur or a third-party accessory.

Sliding dropouts are horizontal and thus it’s possible to acquire optimal chain tension when running a single-speed system by sliding the rear wheel backward.

Multiple Configurations

Sliding dropouts could also be replaceable dropouts. In other words, the user can mount different dropout setups to the frame via bolts.

As a result, it’s possible to run a multitude of configurations such as:

• Standard geared drivetrain with a rear derailleur

• Geared hub with a chain or a belt
• Single-speed (or fixed gear)

It’s also worth mentioning that bolted dropouts allow you to switch between a thru-axle setup and quick-release skewers provided that you can find the needed adapter for your frame.

Sliding Dropouts vs. Eccentric Bottom Brackets

Eccentric bottom brackets allow you to increase or decrease the chain tension by offsetting the bottom bracket.

The principle is very similar to that of an eccentric hub except that the rotation happens inside the bottom bracket shell.

An eccentric bottom bracket is inferior to a set of sliding dropouts for the following reasons:

• An eccentric bottom bracket can only serve as a method to tension the chain. It offers no dropout diversity.

• An eccentric bottom bracket does not affect the bike’s wheelbase and thus cannot improve performance.

• Effective dropouts are easier and simpler to adjust. Eccentric bottom brackets are frustrating.

If the option exists, it’s wiser to go for sliding dropouts rather than an eccentric bottom bracket.

Brakes and Sliding Dropouts

From the perspective of braking, sliding dropouts are ideal in the following cases:

• The bike has disc brakes.

The disc brake caliper is mounted to the sliding dropout. Thus, it moves along with the wheel and the brake pads won’t rub against the rotor after changing the dropout setup.

• The bike has a fixed-gear drivetrain and doesn’t have brakes.

If you’re running rim brakes (V-brakes or cantilevers), you will have to realign the brake pads with the rim after you set the dropouts to a new location. Otherwise, the pads will rub against the rim and/or the tire due to the new position of the wheel.

Sliding Dropouts and Touring Bikes

Sliding dropouts are not all that common on touring rigs (apart from models with a belt drive) primarily because touring bicycles have gears and count on the derailleur to tension the chain.

However, frames with sliding dropouts have a secret benefit when it comes to touring – they allow you to go from multi-speed to single-speed without needing complex tools.

Imagine that your rear derailleur goes bad and can’t serve even as a chain tensioner. If you have sliding dropouts, you can simply shorten the chain with a chain-breaker and then use the sliding dropout to acquire sufficient chain tension in single-speed mode.

Without the sliding dropouts, it will be close to impossible to achieve a decent chain tension because you will have to rely solely on the chain tool.

– Frequently Asked Questions –

In what position should I put the dropouts?

It depends on the terrain and your riding style.

Maximally forward. If the dropouts are closer to the bottom bracket, you’re shortening the effective chainstay length. This property makes the front easier to lift and the bike more agile. For that reason, dirt jumpers and BMXs have fairly short chainstays.

The downside is that the bike becomes less stable during descents and ascents due to the shorter wheelbase. There’s also a higher chance of looping out (the bike sliding in front of you).

This position places more weight on the rear wheel and makes it harder to maintain a higher cadence uphill (rotations of the cranks per minute). A higher cadence is associated with better pedaling efficiency.

Middle position. The mid-position gives you the best of both worlds. The bike is very stable but still somewhat playful. For that reason, this is the default position on many bicycles with sliding dropouts.

Maximally away from the bike. In this position, the bike becomes a climbing and descending beast. If you’re after pedaling efficiency and commuting, this setup could work well. The downside is that the bike is now less suitable for aggressive riding and tricks.

Another benefit of this setting is the additional tire clearance that would allow you to run bigger tires and/or full fenders without issues. The maximally forward position has the opposite effect.

Are sliding dropouts as strong as standard dropouts?

One cannot definitively say that sliding dropouts are stronger or weaker.

Regardless of type, dropouts should be strong enough to handle the stresses that a particular bike will face. For instance, the sliding dropouts on a hardcore hardtail are expected to be much stronger than the standard dropouts found on a carbon road bike.

In other words, it’s more important to get the right frame/bike for your riding discipline than to obtain the strongest dropouts in the world.

Why are sliding dropouts less common and so expensive?

• Low Demand

The vast majority of cyclists are beginners and do not even know what a dropout is nor do they care.

Most people simply want to get on their bikes and ride away without worrying about technical stuff. The low demand results in a low incentive to implement similar features.

As a result, sliding dropouts are seen as a niche/premium feature. The absence of mass production caused by low demand naturally leads to higher prices and a small market share.

• No Need

Sliding dropouts are nice to have, but they aren’t a fundamental feature in most cases. If the bike model and its overall properties satisfy your needs on every other level, then the dropouts should not be a deal-breaker. I would never abandon a good frame just because it doesn’t have sliding dropouts.

• More Difficult To Make

Sliding dropouts require more machining and are therefore a more labor-intensive product. The higher the skill, the higher the price tag.

The tension bolt on my sliding dropouts bent. What’s the problem?

The tension bolt has two purposes:

• To tension the chain by pushing the rear wheel/
• To ensure that the rear wheel has an even and consistent lateral and horizontal position.

The tension bolt does not have a support function. If it’s bent, the most likely problems are:

1. The user has first tightened the dropout support bolts. Then the tension bolt has been overtightened against the support bolts.
2. The dropout is not secure and is pressuring the tension bolt.

In the first case, the fix is straightforward. Replace the tension bolt with a “healthy” one. Set the chain tension first. Tightend the dropout support bolts.

In the second case, it’s necessary to carefully examine the dropout bolts to find out why they are sliding.

It’s possible that washers are missing or maybe the support bolts have damaged threads.

In all cases, it’s not safe to ride a bike with a moving rear wheel. Skip training until the problem is fixed.

Are there 29″ hardtail frames with sliding dropouts?

Yes, there are quite a few models. Below is a short list:

1. Surly Karate Monkey
2. Canfield Nimble 9
3. Soma Juice
4. Kona Honzo
5. Panorama Taiga
6. Cotic Solaris
7. Pace RC29
8. Ragley Big Wig
9. Esker Hayduke

What Are The Downsides of Sliding Dropouts?

If the quality is decent, sliding dropouts don’t have major downsides. The main issue is the added complexity and the greater number of involved parts. In other words, sliding dropouts have more parts that can potentially break.

Sometimes it’s difficult to center the wheel laterally.

Lists Of Frames With Sliding Dropouts Divided By Type

Gravel Frames With Sliding Dropouts

Hardtails with Sliding Dropouts