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by James Huang
April 30, 2020
Photography by DT Swiss
DT Swiss debuted its new Ratchet EXP freehub architecture on the 180 flagship range back in May 2019, and as expected, that update has now made its way into the extremely popular 240 collection. This isn’t just some minor tweak; it’s a major redesign of a system that has been mostly unchanged for decades.
The core of DT’s legendary driver mechanism has been two identical ratchet rings that are each pushed together by a conical spring. It’s been simple, reliable, and with so much contact area between the two rings, the system can handle impressive amounts of load (assuming proper maintenance and the correct lubricant is used, of course).
That new Ratchet EXP mechanism technically still uses the same interface, but DT Swiss reverts back to the old Hügi days by only having one of those rings moving back and forth along the axle; the other one is fixed in place inside the hub shell. DT Swiss claims this simplified arrangement yields reduced wear and even better reliability, while also slightly reducing the time it takes for the ratchets to engage.
The new EXP system (top) requires fewer parts than the existing design, which generally bodes well for long-term reliability.
Fixing the inner ratchet inside the hub shell also allows DT Swiss to hollow out that ratchet ring and tuck the driveside axle bearing inside. This moves the bearing outboard on the axle and spreads the two main bearings further apart for what DT Swiss claims is a “15% improvement” in axle stiffness. More importantly for end users, however, is reduced stress on those bearings and a resultant increase in bearing lifespan.
The new configuration uses fewer parts and shaves off a few grams, too.
As nice as the new Ratchet EXP system sounds, though, professional shop and amateur home mechanics are likely to be most excited about one of the more mundane — but yet absolutely brilliant — improvements on the new 240 hubs. New machining on the hub end caps now leaves a raised ring at the end that can be easily grabbed (and removed) with bare hands, greatly simplifying configuration changes and basic maintenance.
In fact, it’s something I’d love to see made standard on every hub with press-fit end caps, regardless of brand.
The wider bearing spacing on the new EXP architecture (top) should yield better bearing life than the old design (bottom).
DT Swiss will offer the new 240 in four different variants for riders that wish to build their own wheels from scratch: the 240 EXP Classic Road (116 g front; 212 g rear) with conventional spoke flanges for bikes with rim brakes; the 240 EXP Straightpull Road (102 g front; 191 g rear) for use with rim brakes and straight-pull spokes; the 240 EXP Classic MTB 113 g front; 208 g rear) with conventional spoke flanges for disc-brake bikes; and the 240 EXP Straightpull MTB (104 g front; 199 g rear) for disc-brake bikes and straight-pull spokes.
Most of the hub models are offered in a range of spoke drillings and axle end cap dimensions, and all are offered with a variety of aluminum freehub bodies as well. Ratchet tooth configurations, however, are limited to 36-teeth (10-degree engagement) and 54-teeth (6.67-degree engagement), which might disappoint some trail riders.
Retail prices for all variants are US$221 / €150 for the front, and US$434 / €294 for the rear.
At some point soon, too, DT Swiss will also begin incorporating the new internals into its own complete wheelsets, and third-party brands that utilize DT Swiss internals will soon start featuring the new Ratchet EXP design as well.
DT Swiss will offer the new 240 EXP in the usual variety of styles, including both rim-brake and disc-brake (the latter in six-bolt or Center Lock), traditional or straight-pull spoke flanges, and a wide range of axle fitments, freehub bodies, and spoke drillings.
The simplified layout should make for easier maintenance, too.
One of the hallmarks of DT Swiss’s Star Ratchet driver design is the enviable reliability, partially owing to the relatively large amount of surface contact between the mating surfaces as compared to traditional pawl-type ratchets.
Ratchet rings are available with either 36 or 54 teeth depending on your preferences for engagement speed, noise, and friction.
The raised ring on the end caps is brilliantly simple in that it allows for much easier removal than the old smooth-walled design.
All the usual bases are covered in terms of freehub body styles.
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