Revelate Designs Terrapin System 14L vs Topeak BackLoader X 15L
Two seat packs, measured against each other on the figures that decide whether they work on a bike.
The short answer
The Terrapin System 14L takes how far it reaches back, tire clearance and weight; the BackLoader X 15L takes capacity, price and value per litre. Which of those you care about depends on the frame you are fitting it to.
Assembled from the differences below rather than written over them. Every figure is a published measurement or computed from one — nobody here has used either one.
Where they differ
6 of the 6 things we can measure come out differently.
Capacity
1L more in the BackLoader X 15LThe maker's own figure. Worth reading alongside the dimensions below rather than on its own — two bags of the same litreage can want very different frames.
Reach behind the saddle
5cm shorter on the Terrapin System 14LLength is the lever arm on the seatpost, and the longer lever is what makes a loaded pack sway. Shorter is easier to live with; longer usually means more volume. It is a trade, not a fault.
Depth
4cm shallower on the Terrapin System 14LDepth is what competes with the rear tire once the pack sags under load. On a small frame or a big tire this is the measurement that decides it.
Weight
38g lighter on the Terrapin System 14LEmpty weight as published. Worth holding against capacity rather than alone — the lighter bag is not the better one if it carries a third less.
Price
$89 between themManufacturer's price as we hold it.
Per litre
$6.97 per litre between themPrice divided by the maker's capacity. A crude measure that still catches the case where the dearer bag is also the bigger one, which the price alone hides.
Side by side
Including the rows where they are level.
| Revelate Designs Terrapin System 14L | Topeak BackLoader X 15L | |
|---|---|---|
| Capacity | 14L | 15L |
| Reach behind the saddle | 46cm | 51cm |
| Depth | 20cm | 24cm |
| Weight | 567g | 605g |
| Price | $219 | $130 |
| Per litre | $15.64 | $8.67 |