What's the difference between a road bike and a gravel bike? How to tell the difference between them

Fatter tire size

One of the features of gravel bikes is thick tires. While 25C or 28C at the thickest is the norm for regular road bikes, gravel bikes come standard with thicker tires such as 38C and 40C.

The tire size is clearly larger between 25C and 38C even at a quick glance in a photo, so if the bike “looks like a road bike but has thicker tires,” it is more likely to be a gravel bike.

Number and location of dowel holes

The characteristics of gravel bikes that match the characteristics of gravel bikes on unpaved roads are used for travel purposes, such as bicycle camping. For this reason, gravel bikes have more holes on the frame/fork, called dowel holes, for mounting accessories and other items in order to increase the load capacity.

Most regular road bikes have two dowel holes, one under the downtube and the other on the seat tube, for mounting drink holders, but gravel bikes have dowel holes in the following three locations (depending on the make and model) in addition to those two.

1. front fork
2. top tube
3. under the downtube

Two dowel holes are sufficient for normal cycling, but for travel use, they are very important for carrying a sleeping bag, change of clothes, tent, etc. Therefore, the number of dowel holes is very important.

Therefore, the number of dowel holes is one of the characteristics that distinguish a gravel bike.

Gravel-specific groupset

With the rise of gravel bike riding in the past few years, bicycle parts manufacturers have released gravel-specific group sets.

Therefore, it is possible to identify a bike as a gravel bike if it has a gravel-specific groupset.

The following three group sets for gravel from major composite makers are listed below.

1. Shimano: GRX
2. campagnolo: EKAR
3. SRAM: XPLR

However, gravel bikes are not necessarily equipped with a gravel groupset, as some gravel bikes are equipped with a groupset for road bikes or MTBs.

In this sense, the difficulty is that you can only distinguish “gravel bike if it has a gravel groupset”.

Smaller sized wheels

Road bikes are often equipped with wheels that are standardized as 700C, and most gravel bikes inherit this standard, but some gravel bikes are equipped with wheels that are one size smaller, 650B.

The advantage of the 650B wheel size is that the smaller inner diameter of the wheel allows larger tires to be mounted on the same frame.

For this reason, some “all-road” road bike models are designed to be enjoyed as either a road bike when fitted with 700C, or a gravel bike when swapped to 650B.

Since there is not much advantage to installing narrow 650B tires on a body that can accommodate 700C, if the bike is “a road bike but has thick tires on 650B wheels,” it may be a gravel bike.

However, there are some road bikes that dare to use 650B wheels if they are smaller size suitable for women, so “650B = gravel bike” is not necessarily true.