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Geometry cluster · Practical

How to compare two bikes by geometry (in the right order)

Quick answer

Compare in this order: 1) reach and stack (where your body sits); 2) head angle and trail together (stability comes from trail, not the angle alone); 3) the wheelbase split into front center and chainstay; 4) the seat angle corrected to effective; 5) BB, standover and ETT last. Never compare by S/M/L size.

Putting two geometry charts side by side and not knowing where to start is normal. The trick isn't to look at every number, it's to read them in order of impact and know which ones lie when read alone.

Two bikes can share the same reach and feel completely different. And two with different reach can fit you the same. The chart doesn't fool you; reading it out of order does.

The order that matters

1 · Reach and stackThese are the two coordinates of your cockpit: how much room you have standing (reach) and at what height (stack). They compare bikes better than any size label. For a single figure, use the stack-to-reach ratio to see which is more aggressive.
2 · Head angle + trailHere's the classic mistake: comparing the angle alone. Two bikes with the same head angle can have different trail depending on fork offset, and trail is what governs stability. Read them as a pair.
3 · The wheelbase, in partsAn equal wheelbase can split very differently. Separate front center (front half, front-wheel grip) and chainstay (agility and rear traction). The sum doesn't tell you where the feel comes from.
4 · Seat angle, correctedThe catalogue figure is effective and measured at a specific height; raise the saddle and it slackens. To compare for real, check the reference height, or use the actual angle. It affects how much weight you carry over the rear when climbing.
5 · The rest, lastBB drop, standover and ETT fine-tune, but rarely decide between two good candidates. Check them once everything else has tied.
Common mistake: comparing two bikes by their size (S/M/L) or by a single "headline" number. Size isn't standardised across brands, and equal reach with different stack already changes your posture. Compare coordinates and pairs, not labels.

A mental shortcut

If you only have 30 seconds: look at reach, stack and trail. Those three figures tell you where you sit and how the steering will behave — 80% of the feel. Everything else is fine-tuning. For the detail of what each number produces, the number-to-feel table is the full map.

Torn between two bikes?

Send us both geometry charts and we'll tell you, number by number, how they really differ and which fits you better for how you ride. Message us on WhatsApp

Related

Bike geometry explained → Reach vs frame size → Number-to-feel table → Sensitivity ranking →

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BikeLab-pedia · Geometry cluster / Bike geometry explained / Carlos Eduardo Ravello Joo · BikeLab Studio · Trujillo, Peru