35 mm, 45 mm or 60 mm: Choosing the Right Rim Depth
A wheel can look fast in the shop and feel demanding on an exposed descent. Choosing between 35 mm, 45 mm and 60 mm rims means balancing aerodynamic potential, weight and handling against the roads you actually ride. For many cyclists, 45 mm is a sensible starting point for mixed road use. A shallower or deeper option becomes more attractive when your terrain, riding priorities and wind conditions point clearly in that direction.
The important detail: carbon wheel rim depth describes a dimension, not a performance rating. Rim shape, tyre choice and the complete wheel design can change the result substantially.
What rim depth changes
Rim depth is the distance from the rim’s outer edge towards the hub, measured across its profile. It is separate from internal rim width, which helps determine tyre compatibility and the shape of an inflated tyre.
A deeper rim gives designers more surface over which to manage airflow around the wheel. It also exposes more area to crosswinds. Cycling UK’s guide to bicycle wheels identifies this aerodynamic and handling trade-off as a basic consideration when choosing rims.
Deeper designs also often weigh more within an otherwise similar wheel range, although construction differences can reverse that comparison between brands.
Aerodynamic savings generally become more significant as riding speed increases. There is no universal speed at which deep section wheels suddenly start working, and depth alone cannot tell you how many watts a wheel will save.
Comparing 35 mm, 45 mm and 60 mm rims
These are useful starting points rather than guarantees about individual wheelsets.
| Rim depth | Riding that often suits it | Main attraction | Main consideration |
|---|---|---|---|
| 35 mm | Long climbs, exposed routes, varied endurance riding | Often lower weight and less demanding handling | May give up aerodynamic efficiency to a well-designed deeper wheel |
| 45 mm | Rolling roads, club rides, mixed terrain | A practical balance of aerodynamic potential and everyday usability | Still needs assessment for crosswind behaviour |
| 60 mm | Fast road riding, sustained solo efforts, flatter racing | Greater scope for aerodynamic optimisation | Wind handling and possible additional weight |
35 mm: climbing and exposed roads
A 35 mm wheelset makes sense when long climbs and windy descents feature heavily in your riding.
On slow, steep climbs, aerodynamic differences matter less than they do on fast roads. Lower total weight becomes more useful, so compare actual wheelset weights rather than assuming every shallow wheel is lighter.
Remember that the rider, bike and equipment all contribute to the mass travelling uphill. A modest wheel weight difference is only a small part of that total.
Shallower rims can also make exposed riding less demanding. That may be particularly valuable if gusts regularly interrupt your descending or leave you gripping the bars tightly. However, a 35 mm rim remains affected by wind; its depth does not guarantee calm handling.
45 mm: a practical choice for rolling terrain
Around 45 mm is a useful place to begin when buying one road wheelset for varied routes.
Rolling rides include plenty of time on flats, gentle gradients and descents, where aerodynamics remain relevant. Choosing solely around the steepest climb can overlook most of the ride.
A well-designed wheel at this depth can offer useful aerodynamic performance while remaining manageable across a broad range of conditions. Whether it suits you depends on the particular wheel, your tyres and your confidence in wind.
For a typical mix of solo rides, group outings and occasional events, compare several wheels around this depth before deciding that you need something shallower or deeper.
60 mm: sustained faster riding
A 60 mm rim deserves consideration when much of your riding involves maintaining speed on open roads.
Fast solo efforts and flatter events give aerodynamic improvements more opportunity to influence your ride. Short hills do not automatically make a deeper wheel unsuitable, particularly when speeds remain relatively high.
The qualification is handling. If a wheel makes you sit upright, brake frequently or hesitate on exposed sections, those responses can outweigh a small aerodynamic advantage.
Also check the evidence behind the upgrade. Moving from 45 mm to 60 mm does not guarantee a worthwhile improvement, especially when comparing different rim shapes and tyre combinations.
Crosswinds: steering response matters as well as sideways force
A crosswind can push the bicycle sideways and create a turning force at the steering. How abruptly those forces change matters to the rider.
The front wheel deserves particular attention because aerodynamic forces acting on it can influence steering directly. Rim shape and the tyre’s profile affect airflow, so two wheels of equal depth can behave differently in gusts.
Rider mass, bike geometry, experience and exposure also influence how manageable a setup feels. There is no reliable rider-weight cutoff or universal wind-speed limit for a given depth.
Consider where gusts reach you: gaps in hedges, bridge crossings, coastal roads and exposed descents can produce sudden changes even when much of a route feels sheltered.
A shallower front wheel paired with a deeper rear is one possible compromise—for example, 45 mm at the front and 60 mm at the rear. The rear still contributes to wind forces on the bicycle, so assess the complete setup.
What to compare beyond the depth number
The rim and tyre together
The tyre forms the leading part of the wheel’s aerodynamic profile. Its mounted width and shape affect how air meets the rim.
Check whether performance testing used a tyre similar to yours. A result obtained with a narrow road tyre may say little about the same wheel fitted with a much wider tyre.
Internal width affects tyre shape and compatibility; external width contributes to the aerodynamic profile. Neither measurement should be considered alone. Choose an approved tyre and rim combination that provides the grip and riding characteristics you need.
Test conditions
When assessing aerodynamic claims, look for:
- The test speed and tyre specification.
- A range of airflow angles, often called yaw angles.
- Whether testing used an isolated wheel, a complete bicycle or a bicycle with a rider.
- Comparable conditions for every wheel being compared.
A headline saving from unrelated tests is a weak basis for choosing between wheelsets. Drag measurements also do not fully describe how a wheel responds to sudden gusts.
Your surface and tyre priorities
For gravel riding, tyre volume, tread, pressure and durability can have a larger practical influence than a small change in rim depth. A 35 mm gravel wheel and a 35 mm road wheel may have very different widths, construction and intended use.
Aerodynamics can still matter on fast gravel routes, but road-wheel results should not be transferred directly to wide, treaded tyres.
Make the choice around your regular rides
Start with your usual terrain and the conditions you ride through most often. Then shortlist compatible wheels and compare their actual weights, aerodynamic evidence and reported handling.
If possible, test a similar front wheel on a familiar route in manageable wind. Notice whether you can hold your line comfortably and maintain your normal riding position.
Choose 35 mm when climbing and exposed-road handling lead your priorities. Start around 45 mm for varied road use. Consider 60 mm when sustained speed matters enough to justify closer attention to wind behaviour. Let the complete wheel and tyre setup earn the purchase, rather than choosing by depth alone.