In our Tech Q&A series, we tackle cycling queries – big or small, complex or simple – with insights from the BikeRadar team and trusted industry experts. Next up, a reader wants to know about pedal-system stack heights
"Which road bike pedal system has the lowest stack height?"
Sam Palin-Mckee
Stack height for a pedal system is a determinant of pedalling efficiency, so a lower pedal stack height is, as a rule, better.
We wouldn't expect a huge jump in performance from lowering your pedal stack height by a few millimetres, but a lower figure is nevertheless 'nice to have' all else being equal.
Of course, it’s not only pedal stack height that matters for a clipless pedal – you also need to take account of the cleat’s contribution to the actual distance between the centre of the pedal axle and the bottom of your shoe.
The shoe itself adds yet more distance between your foot and the pedal, which is one reason why you’ll find carbon soles on top-flight cycling shoes; as well as being stiffer, they can also be made thinner.
Most – though not all – pedal manufacturers tend to quote the total stack height of the pedal plus cleat combination and not the two parts separately, so in the table below we've calculated some values of popular models.
Best road pedals for low stack height
Here’s a table of stack height for the pedal-plus-cleat combo and for the individual components.
| System | Pedal plus cleat | Pedal | Cleat |
|---|---|---|---|
| Shimano Dura-Ace PD-R9100 | 14.6 | 9.3 | 5.3 |
| Shimano Ultegra PD-R8000 | 15.8 | 10.5 | 5.3 |
| Shimano 105 PD-R7000 | 16.5 | 11.2 | 5.3 |
| Look Keo Blade | 14.8 | 8.5 | 6.3 |
| Look Keo 2 Max | 17.3 | 11 | 6.3 |
| Look Keo Classic | 17.8 | 11.5 | 6.3 |
| Wahoo Speedplay with baseplate | 11.5 | 11.5 | 0 |
| Wahoo Speedplay without baseplate | 8.5 | 8.5 | 0 |
| Time Xpro/Xpresso | 14.7 | 9.7 | 5 |
| Ekoi PW8 | 8 | 8 | 0 |
| Power meter pedals | |||
| Garmin Rally RS110/210 | 17.5 | 12.2 | 5.3 |
| Garmin Rally RK110/210 | 18.5 | 12.2 | 6.3 |
| Wahoo Powrlink Zero | 13 | 13 | 0 |
| Look Keo Blade Power | 17.1 | 10.8 | 6.3 |
| Favero Assioma PRO RS | 15.8 | 10.5 | 5.3 |
| Favero Assioma Duo | 16.8 | 10.5 | 6.3 |
All figures in mm
The best pedal for stack height is the Ekoi PW8. This has a quoted stack height of 8mm, but requires a specialist road cycling shoe designed to fit – currently only made by Ekoi and, at full price, costing more than £450.
The Wahoo Speedplay system is next best, particularly if you have shoes with four bolt holes and can mount the pedal without the baseplate, when the stack height is only 8.5mm. As with Ekoi’s shoes, such shoes are a rarity, though.
Even with the baseplate to convert the cleats to fit on shoes with three bolt holes, its stack height is only 11.5mm.
Stack height for power meter pedals is usually quoted without the cleat, making them appear to have a lower stack height than non-instrumented pedals. This usually isn't the case, though, so we've done the maths to show you the true pedal-plus-cleat stack height for all systems.
We reckon there might be a new pedal system on the way from Shimano, though, possibly with a lower stack height and including a power meter option, which might upset the apple cart.
