When you think German trail hardtails, one imagines gorgeous aluminium welds and industrial design. But not everything about the German metal bike industry starts and ends with Nicolai.

Founded in 2018, Sour is a Dresden bike brand with steel sensibility in terms of frame material.

The brand has updated its Crumble hardtail for 2021 and if you want something with an elegant steel appearance and contemporary design details, this is certainly a frame worth considering.

Read more: these are the best hardtail mountain bikes 

Modern trail geometry – instead of a hardcore hardtail

The Crumble is constructed with double-butted chromoly and Sour’s designers have updated its geometry, increasing the bike’s reach.

As a reference guide, the size large Crumble stretched to 467mm of reach and balances its rear triangle geometry with 425mm chainstays.

Intended to run forks in the 120-140mm travel range, the Crumble sits at a 66.5° head angle and is offered in four frame sizes. The extra-small option runs 27.5” wheels, whilst the remaining three sizes (medium-through-extra-large) are configured for the 29” wheel diameter.

Overall geometry is comfortably between that of a trail and light-enduro hardtail.

Tidy detailing

The 31.6mm seat tube has stealth routing and is large enough in diameter to accommodate most of the latest long-travel droppers. A neat design touch is Crumble’s integrated seat clamp.

Internal cable routing also ports into the frame’s downtube, just aft of its headtube junction and exits ahead of the bottom bracket.

Like all proper trail hardtails, the Crumble uses a threaded bottom bracket to lessen the annoyance of creaking. If you feel the need to fit a chain device, in anticipation of rushing the rootiest and rockiest of trails, there are mounting tabs.

The slightly repackaged 2021 frame geometry has allowed Sour to add a second hydration bottle mounting position inside the main triangle.

Sour says that a size medium Crumble weighs 2710g and frames are now available for order at €799.