Head to head
Bontrager Aeolus RSL 51vsZipp 404 Firecrest
Both sections drawn to one scale, from each maker's published geometry. The differences you can see in the drawing are the differences that exist.
vs
Fig. — rim sections, one scale
Bontrager Aeolus RSL 51Zipp 404 Firecrest
- Depth
- 7 mm apart
- 51 vs 58 mm
- External
- 3.5 mm apart
- 31 vs 27.5 mm
- Internal
- Identical
- 23 vs 23 mm
- Claimed weight
- 66 g apart
- 1,450 vs 1,516 g
- UK RRP
- £200 apart
- £2,200 vs £2,000
Rim depth
51 mm
58 mm
7 mm apart. Deeper is faster on the flat; shallower is calmer in crosswind and lighter uphill. Neither is simply better.
Internal width
23 mm
23 mm
Identical — both suit the same tyre widths.
External width
31 mm
27.5 mm
Governs how the rim and tyre meet the air, and frame clearance.
Bontrager
Aeolus RSL 51
RRP £2,200
UCI mass-start road
Eligible — Eligible on the rules we assess
Zipp
404 Firecrest
RRP £2,000
UCI mass-start road
Eligible — Eligible on rim height; tyre choice is restricted