29 inch bike gears: keep BERG 3.0 three-by-seven and TZ500 together
29 inch bike gears are not counted by wheel diameter. The BERG 3.0 product page describes its transmission as 3X7 and also lists 21 in the gear-count field. For a buyer comparing specifications, the rear component names and tooth range add information that the headline total leaves out.
Put the 29 inch bike gears count beside the rear range
Kross names Shimano TZ500 in a combined cassette/freewheel field and gives 14–34T in the separate range field. Copy both entries when asking about the advertised rear cluster. The combined heading should not be treated as proof that cassette and freewheel attachments are interchangeable.
The rear derailleur is listed as Shimano Altus M310. That identifies a different component from the rear cluster. Someone asking about worn teeth, a damaged derailleur or an unfamiliar control may need different information, even though all three questions begin with the bicycle's gears.
Understand what three-by-seven does not measure
Three front selections multiplied by seven rear selections explain the nominal twenty-one combinations. That arithmetic does not establish twenty-one distinct ratios, equal steps between gears or a measured climbing result. The crank row does not give the chainring tooth counts needed for a complete numerical ratio comparison.
Use the Black Glossy BERG 3.0 listing to keep the exact bicycle in view. Its parent contains both 27.5-inch and 29-inch configurations. A wheel-format label alone supplies neither the rear range nor a reason to import gearing from a different Kross family.
Look at the drivetrain without identifying invisible parts
The historical FOCUS photograph shows exposed front and rear transmission hardware. Its visible 50-559 tyre marking belongs to a different, 26-inch comparison bicycle. The image helps locate the components being discussed; it does not verify TZ500, M310 or any tooth count for the BERG.
When comparing an actual offer, retain the advertised component list and request readable markings from the installed parts. Record changes separately if a previous owner replaced the transmission. This prevents an original specification and a seller's fitted equipment from being merged into one unsupported description.
The 29-inch bike topic is a useful browsing category, while the Kross introduction distinguishes its broader model families. Neither should replace the detailed transmission entries when a particular range or part matters to the purchase.
FAQ: Count, range and component names
Why do 3X7 and 21 appear together?
They describe the nominal three-front by seven-rear arrangement and its combination count.
What rear tooth range is published?
The inspected BERG 3.0 range field gives 14–34T.
Is M310 the name of the rear cluster?
No. Kross uses M310 for the rear derailleur and TZ500 in the cluster field.
Reference: BERG 3.0 drivetrain specification (https://kross.pl/berg-3-0-czarny-szary-polysk).
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