How to choose a bottle cage for mounting under the downtube

“Dowel holes under the downtube” is a feature of gravel bikes

For road bikes, it is standard to have two dowel holes for bottle cages, one on the down tube and the other on the seat tube.

On the other hand, gravel bikes have additional dowel holes under the downtube and on the front fork, etc., to increase loading capacity.

Clearance is severe under the downtube depending on bike configuration.

It is nice to be able to make effective use of the normally dead space under the downtube, but since the downtube is where the drivetrain (front crank and chainring) turns, it is necessary to install the bike so that there are no problems with the drivetrain.

Gravel bikes with a single front configuration have relatively wide clearance, but cranks with a double front, especially those with a large inner chainring, such as semi-compact or normal cranks, may cause the bottle cage to hit the tuning ring or chain If the cranks are designed for MTB, the bottle cage may hit the tuning ring or chain.

For MTB cranks, the distance between cranks, called the Q-factor, is wide enough to allow a good clearance even with front multi-stage cranks, but when using double cranks for road use, the Q-factor is quite narrow, so the probability of the chain or chainring hitting the bottle cage is high. The probability of the chain or chainring hitting the bottle cage increases.

Also, because the dowel holes are located in different places on different bikes, some bikes may have a narrow Q-factor crank with a large inner chainring, which is not a problem.

How to choose a bottle cage that does not affect the front drive

Recommend a “slim” and “top holding” type.

The problem is a wide bottle cage, so choose a “slim” bottle cage with a narrow width. The shape of the bottle cage is also a key factor in choosing a bottle cage.

Bottle cages that have a ring that grows out from the bottom to hold the bottle in place are more likely to have the bottom part interfering with the cranks. In the image at the top of this article, the type on the right is the one that grows from the bottom.

On the other hand, the left type of bottle cage in the top image of this article, in which the holding portion grows from the top, has a wider width at the far side from the crank, so it is less likely to interfere with the chainring.

Choose a narrower bottle itself!

If you are using a crank with a narrow Q-factor, some bottles may be of a size where the bottle width interferes with the crank.

Even if the bottle cage is narrow, it is useless if the bottle is too thick, so it is a good idea to buy a slimmer bottle. However, bottles that are too narrow may pop out of the cage, so you will have to experiment in this area to find the best combination.

It is also important to choose a bottle cage that "does not fall out.

Bottle cages come in a variety of shapes and sizes. Some products are centered farther apart to make it easier to remove the bottle, while others have fewer areas to hold it.

When installing a bottle cage under the downtube, it is important to select a bottle cage of a shape and size that "holds the bottle securely and prevents it from falling out.

Particularly when riding on gravel, the vehicle body will be more violent than on paved roads, so care should be taken to ensure that the bottle does not pop out with the impact.

Use “Velocro straps” if you want to improve the fixation.

If you are concerned about the bottle popping out of the bottle cage, use a Velocro strap to secure the bottle to the bottle cage.

By putting the strap through the bottle cage and wrapping the Velocro around the bottle cage arm so that it is held inward from both sides, the bottle can be held in place considerably better.

Velocro straps sell for about $1 each, so this is a more cost-effective way to increase the holding power than going on a journey to find a bottle cage with a higher holding power that fits your bottle.