Specialized Tarmac SL9 vs Trek Madone Gen 8: geometry and fit comparison
Matched sizes, stack and reach deltas, and a fit check against your own body instead of guessing from two separate size charts.
The Specialized Tarmac SL9 is built as a race geometry frame, the Trek Madone Gen 8 as a race geometry frame. The Trek Madone Gen 8 cockpit is slightly shorter, by about 5 mm. Across matched sizes the Specialized Tarmac SL9 and Trek Madone Gen 8 front ends are within a few millimetres of each other, so posture will depend more on cockpit setup than on the frame.
Switching from a Specialized Tarmac SL9?
Your closest Trek Madone Gen 8 size, and what will still feel different about the position.
| You ride the Specialized Tarmac SL9 in | Take the Trek Madone Gen 8 in | The position will feel |
|---|---|---|
| 44 | XS | 6 mm taller · 4 mm longer |
| 49 | XS | 7 mm lower · 5 mm shorter |
| 52 | S | 3 mm taller · 2 mm shorter |
| 54 | M | 2 mm taller |
| 56 | ML | 3 mm lower · 6 mm shorter |
| 58 | L | 9 mm lower · 8 mm shorter |
| 61 | XL | 2 mm lower · 6 mm shorter |
Which one fits you better?
Run the same measurements through both frames. The likely size and the full fit report can differ more than the spec sheets suggest.
What Specialized Tarmac SL9 size fits you?
Get an instant frame estimate, then continue into the full fit report to check cockpit reach, bar drop, and setup risks before you buy.
No account needed for this check. The full report keeps this bike preselected.
What Trek Madone Gen 8 size fits you?
Get an instant frame estimate, then continue into the full fit report to check cockpit reach, bar drop, and setup risks before you buy.
No account needed for this check. The full report keeps this bike preselected.
FAQ
Which has the taller front end: Specialized Tarmac SL9 or Trek Madone Gen 8?
Across matched sizes the Specialized Tarmac SL9 and Trek Madone Gen 8 front ends are within a few millimetres of each other, so posture will depend more on cockpit setup than on the frame.
Can the same rider take different sizes on these two bikes?
Yes, and it happens often: frame labels are not standardized. Use the matched-size table for geometry, then run the fit check below with your own measurements for each bike.
Free tools are just the start
TrainCraft builds structured training plans and adapts them when life gets in the way — powered by real fatigue science (CTL/ATL/TSB). Free to start.