Specialized Tarmac SL9 vs Trek Madone Gen 8: which bike is right for you?

Compare ride character, intended rider, geometry, and fit. Add your measurements to see which bike suits you better and which size to choose on each.

Fit verdict: the frame positions differ enough to matter. Compare the geometry below, then use your measurements to identify the safer size and setup.

Compare them for meCompare geometry and sizes

In one look

Specialized Tarmac SL9: race geometry. Trek Madone Gen 8: race geometry.

  • 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.
  • The Trek Madone Gen 8 cockpit is slightly shorter, by about 5 mm.

We compare differences at frame and model level. Components, current price, and availability depend on the exact build and seller.

2026 • race geometry
Specialized Tarmac SL9
Full size guide
2025 • race geometry
Trek Madone Gen 8
Full size guide

Fit and size differences

Geometry can separate these bikes: matched sizes create a meaningfully different position.

Median difference across matched sizes: stack 2 mm, reach 5 mm.

For a personal answer, the fit-and-size path uses your measurements to show only the relevant frame sizes. The full chart remains available as a reference.

View geometry for every size

How do Specialized Tarmac SL9 and Trek Madone Gen 8 sizes compare?

See the closest size matches and the differences in stack, reach, and riding position.

Specialized Tarmac SL9
44
Stack 501, Reach 366
Trek Madone Gen 8
XS
Stack 507, Reach 370

Stack: 6 mm taller

Reach: 4 mm longer

Specialized Tarmac SL9
49
Stack 514, Reach 375
Trek Madone Gen 8
XS
Stack 507, Reach 370

Stack: 7 mm lower

Reach: 5 mm shorter

Specialized Tarmac SL9
52
Stack 527, Reach 380
Trek Madone Gen 8
S
Stack 530, Reach 378

Stack: 3 mm taller

Reach: practically identical

Specialized Tarmac SL9
54
Stack 544, Reach 384
Trek Madone Gen 8
M
Stack 546, Reach 384

Stack: practically identical

Reach: practically identical

Specialized Tarmac SL9
56
Stack 565, Reach 395
Trek Madone Gen 8
ML
Stack 562, Reach 389

Stack: 3 mm lower

Reach: 6 mm shorter

Specialized Tarmac SL9
58
Stack 591, Reach 402
Trek Madone Gen 8
L
Stack 582, Reach 394

Stack: 9 mm lower

Reach: 8 mm shorter

Specialized Tarmac SL9
61
Stack 612, Reach 408
Trek Madone Gen 8
XL
Stack 610, Reach 402

Stack: practically identical

Reach: 6 mm shorter

The same size label can create a different position on each frame. Stack and reach are one part of the decision; the personalized comparison connects them to your body and each bike’s ride character.

FAQ

Can the same rider take different sizes on these two bikes?
Yes. Frame labels are not standardized, so the same rider may need different sizes. This comparison deliberately avoids a generic matched-size answer and hands your measurements to Bike Fit instead.
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.

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