Resources / Technical guides / 23.5 mm vs 25 mm inner width
Product Development News | July 2026
25 mm Inner-Width Option Enters Tooling for DeerCycles' 30 mm Carbon Rim Family
A second inner-width direction for OEM buyers who need a different route toward a lower rim-weight target while retaining the project's required strength level.
Development renders compare the two inner-width directions. Internal wall dimensions are intentionally omitted, and the 25 mm render is not a photograph of a finished sample.
What is changing?
DeerCycles is developing a 25 mm inner-width mold insert for the asymmetric, hooked carbon rim family currently offered with a 23.5 mm inner width. Both directions use the same nominal 30 mm outer-width target and 2.5 mm center offset.
The 25 mm tooling program covers 35, 40, 45, 50 and 55 mm depths. It adds a second engineering route; it does not replace the existing 23.5 mm platform.
Why we started the 25 mm option
The project began with a practical lightweight-development problem. On one requested construction, the 23.5 mm geometry could not reach the target weight and required strength level at the same time. Moving to a 25 mm internal geometry gave our engineering team a different cross-section and layup envelope: a wider range of profile and carbon-placement solutions for reaching that combination.
This result belongs to this rim platform. It does not mean every 25 mm rim is automatically lighter or stronger than every 23.5 mm rim.
Platform at a glance
What the mold insert changes
The insert is a production-tooling element that forms part of the rim's internal geometry. It is not an accessory fitted to the finished rim.
With the same outer-width target, changing the inner width changes the space available around the bead area, sidewalls and internal cavity. The 25 mm version is therefore not the 23.5 mm version with material simply removed. Profile and carbon layup have to be reviewed together for the selected depth, target weight and strength requirement.
Buyer rule: choose the development direction from the complete project brief, not from one width number.
Why keep both widths
The established 23.5 mm version remains useful for programs built around that geometry. The 25 mm route gives buyers another starting point when the brief places greater emphasis on a lower rim-weight target while retaining its required validation level.
The final choice depends on the tire system, depth, target weight, validation requirement and wheel-build inputs.
What buyers should review about tire fit
A tire's measured shape can change when it is mounted on a different inner rim width. The 1.5 mm difference can therefore affect mounted tire profile and clearance review even though the rim's nominal outer-width target is unchanged.
The exact tire model, bead format and permitted pressure must still follow the applicable tire and rim documentation. For general background, see the DeerCycles carbon rim inner-width guide and Schwalbe's official tire-dimension guidance.
What to send for an OEM review
For a useful 23.5 mm versus 25 mm discussion, send:
This lets DeerCycles review inner width together with profile and layup direction instead of treating it as an isolated specification.
Frequently asked questions
Is the 25 mm option replacing the 23.5 mm version?
No. The 23.5 mm platform remains available as the established direction. The 25 mm insert creates another engineering route for projects with a different weight-and-strength brief.
Is the 25 mm option available for samples now?
Not yet. Tooling is in progress, and the option is not sample-ready or production-ready. The next milestone is tooling completion, followed by project-specific sample planning and validation.
Which rim depths are included?
The 25 mm tooling program covers the 35, 40, 45, 50 and 55 mm family.
Do both options use the same basic platform direction?
Yes. Both use a nominal 30 mm outer-width target, an asymmetric hooked profile and a 2.5 mm center offset. The internal geometry and carbon construction are not identical.
Is the 25 mm version always lighter and stronger?
No. On this platform, the 25 mm geometry created a development route toward a requested lower weight while retaining the project's required strength level. Final performance belongs to the validated construction, not the width number alone.
Can the same tire be used on both versions?
Do not assume compatibility from the two width numbers alone. Review the exact tire model, mounted dimensions, bead format, pressure limits and the tire and rim makers' documentation.
What is an inner-width mold insert?
It is a tooling element used during molding to define part of the rim's internal geometry. It is not a removable component in the finished rim and it is not a tire insert.
Source Boundary
What this update does and does not claim
The platform geometry, depth family and tooling status are DeerCycles development information confirmed for this update. The tire-fit note is supported by Schwalbe's published guidance. No exact weight saving, wall thickness, production date, universal tire compatibility or final test result is published here.
Discuss the 23.5 mm / 25 mm platform
Share your project brief for an OEM development review, or ask to receive an update when the 25 mm option reaches sample-review status.