Head to head
Bontrager Aeolus RSL 37vsFulcrum Speed 42
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 37Fulcrum Speed 42
- Depth
- 5 mm apart
- 37 vs 42 mm
- External
- 4.5 mm apart
- 31 vs 26.5 mm
- Internal
- 4 mm apart
- 23 vs 19 mm
- Claimed weight
- 60 g apart
- 1,325 vs 1,385 g
- UK RRP
- £300 apart
- £2,100 vs £1,800
Rim depth
37 mm
42 mm
5 mm apart. Deeper is faster on the flat; shallower is calmer in crosswind and lighter uphill. Neither is simply better.
Internal width
23 mm
19 mm
The wider rim is built around a wider tyre. Match this to the tyre you actually run, not to the bigger number.
External width
31 mm
26.5 mm
Governs how the rim and tyre meet the air, and frame clearance.
Bontrager
Aeolus RSL 37
RRP £2,100
UCI mass-start road
Eligible — Eligible on the rules we assess
Fulcrum
Speed 42
RRP £1,800
UCI mass-start road
Eligible — Eligible on the rules we assess