Breezer Thunder Geometry: How the Four Frame Sizes Compare
Breezer Thunder geometry changes substantially across its four listed frame sizes: reach runs from 420 to 485 mm, and standover from 750 to 850 mm. A size choice therefore deserves more than matching a height to a familiar Small or Large label. The current chart provides several dimensions to compare together.
Breezer Thunder geometry across S to XL
| Size | Reach, mm | Stack, mm | Standover, mm |
|---|---|---|---|
| S | 420 | 647.4 | 750 |
| M | 440 | 656.6 | 783 |
| L | 460 | 665.8 | 817 |
| XL | 485 | 675.1 | 850 |
Small to Medium adds 20 mm of reach and 9.2 mm of stack. Large to XL adds 25 mm and 9.3 mm respectively. The horizontal and vertical changes are different, so moving up a size does not simply produce the same bicycle at a uniformly enlarged scale.
Some dimensions remain shared
All four columns list a 67.5-degree head angle, 450 mm chainstay and 29-inch wheels. Seat-tube angle changes from 75 degrees on Small through 74.5 on Medium to 74 on Large and XL. These entries describe the documented frames; they do not tell a rider exactly how another generation will feel.
Understand the labels beside the measurements
The Thunder listing groups 15IN, 17IN, 19IN and 20.5IN under Configuration. See the Breezer Thunder Bike — Heavy Skies listing alongside those details. Those are listing labels, not a promise that converting each number directly into millimetres reproduces the chart’s seat-tube measurement. The manufacturer’s C–T entries are 370, 420, 470 and 521 mm. Keeping nominal labels and actual listed dimensions separate avoids a false contradiction.
The dropper-post entry changes too: Small has 100 mm travel, Medium and Large 125 mm, and XL 150 mm. A decision between neighbouring sizes should therefore consider the complete riding position and installed post, rather than reach alone.
Use height guidance as a starting point
Breezer lists overlapping height bands: Small 5 ft 3 to 5 ft 7, Medium 5 ft 6 to 5 ft 10, Large 5 ft 9 to 6 ft, and XL 5 ft 11 to 6 ft 2. A rider in an overlap is not assigned one inevitable answer by that table. A fitting or demonstration can address the position that a height band cannot settle.
The old ThunderPRO photograph is useful for recognising a different generation before applying these numbers. It was captured in 2009; none of the current chart’s reach, stack or standover measurements is verified for that photographed bicycle.
FAQ
Do all four frames use the same head angle?
Yes. The current chart lists 67.5 degrees for each size.
Does a 17IN label mean a 431.8 mm seat tube here?
No. The chart lists Medium’s C–T measurement as 420 mm.
Can height alone settle a choice between two sizes?
No. The manufacturer’s overlapping bands leave further fitting questions to resolve.
The Breezer model topic keeps the Thunder separate from differently proportioned families. The company guide explains the wider riding categories before those dimensions are compared.
Sources: manufacturer specifications (https://www.breezerbikes.com/products/thunder-25).
Photograph credits and permissions
Photograph 1
Original title: 2010 Breezer Thunder
Creator: Richard Masoner / Cyclelicious; creator URI: https://www.flickr.com/photos/bike/; creator-requested attribution URI: http://www.cyclelicio.us/; creator profile: https://www.flickr.com/people/bike/
Original source URI: https://www.flickr.com/photos/bike/4079688150
License / permission: CC BY-SA 2.0
License / permission URI: https://creativecommons.org/licenses/by-sa/2.0/
Modification notice: Original source-hosted JPEG retained unchanged by this publisher. Earlier source modifications are unassessed.
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