May 2026<\/a>. At that time, the feature was reserved for the eMTB+ and Race riding modes on the Performance Line CX and Performance Line CX-R. It was a targeted tool for riders pushing hard on aggressive terrain. In update 1.38, Bosch has made the technology far more accessible.<\/p>\nDrivetrain Tensioner is now available across all riding modes on the Performance Line CX, the Performance Line CX-R, and the Cargo Line. That means a rider using a tour mode on a long gravel ride, or a commuter running a custom eco mode, can enjoy the same chain management benefits as someone sprinting in Race mode.<\/p>\n
What Drivetrain Tensioner actually does<\/h3>\n
The system applies a very small preload to the motor. This preload is just enough to keep the bike chain taut, but it does not generate any rotational movement. When you begin to pedal, the chain is already in full contact with the chainring and sprocket. The motor does not have to wait for the slack to be taken up before delivering power, and you do not have to hear that familiar metallic \u201cclink\u201d of a chain snapping tight.<\/p>\n
Without Drivetrain Tensioner, the first impulse of pedalling is spent tensioning the chain between the chainring and the rear sprocket. That process eats a tiny amount of your pedal power, and it causes the chain to rub against the teeth with every stroke. With the feature engaged, the chain is held ready, power transfer is more direct, and drivetrain wear is slightly reduced over time.<\/p>\n
The benefit is subtle on a casual ride, but it becomes meaningful in situations that demand instant response. A race start, a steep technical climb, or a quick pedal out of a corner all feel snappier when the drivetrain is already under tension.<\/p>\n
Why Bosch turned the feature off by default<\/h3>\n
Here is where the update gets complicated. Although Drivetrain Tensioner is clearly beneficial for many riders, Bosch has deactivated it by default across all riding modes. In earlier versions, the checkbox was automatically selected when the feature was available. With 1.38, riders will have to enable it manually in the advanced settings if they want it.<\/p>\n
The explanation lies in how the feature interacts with full-suspension bikes. A full-suspension frame is designed to allow the rear wheel to absorb impacts, and the drivetrain should ideally play as little part in that movement as possible. Drivetrain Tensioner applies a constant preload to the motor, which in turn resists the chain\u2019s natural tendency to move with the suspension. The effect is not as violent as strong pedal kickback, but it moves in the same direction: it reduces the responsiveness, sensitivity, and available travel of the rear suspension.<\/p>\n
On a hardtail, a commuter bike, or a cargo bike, there is no suspension trade-off to worry about. The feature should be completely benign, and riders on those bikes are unlikely to notice any downside. On a full-suspension mountain bike, however, Drivetrain Tensioner can dull the feel of the bike\u2019s rear end, which is why the default-off decision is a sensible compromise.<\/p>\n
Riders can still enable it for every riding mode via the advanced settings if they prefer a taut chain and are willing to accept the suspension character change. But the fact that Bosch has switched the default to off suggests the company is being cautious about applying a technology that is not universally beneficial.<\/p>\n
Trick Check gets a dedicated Ride Screen in update 1.38<\/h2>\n
Trick Check has been part of the Bosch Smart System since the 1.34 update, which arrived in April 2026. It was a playful but genuinely useful feature for mountain bikers who wanted to analyse their technique. The system can recognise jumps, wheelies, manuals, and stoppies, then report specific details about each manoeuvre while you ride.<\/p>\n
At first, that information appeared only briefly. After each trick, the display or smartphone screen would show the relevant data for eight seconds, accompanied by a short beep, before returning to the normal ride screen. That was enough for a quick glance, but not enough for riders who wanted to study their form mid-ride or share their numbers with friends at the trailhead.<\/p>\n
Update 1.38 gives Trick Check its own Ride Screen. Once activated, the dedicated screen stays in place until the system detects the next trick. That change makes the feature dramatically more practical: instead of racing to read data before it disappears, riders can keep the trick screen up and watch their wheelie or jump metrics update in real time.<\/p>\n
How to set up the Trick Check Ride Screen<\/h3>\n
Setting it up requires a specific display configuration. In the eBike Flow app, go to the display configuration settings and add the \u201cTrick Check\u201d Ride Screen. The key limitation is that Trick Check only works as a full-screen layout. If you want to combine it with other data fields on the same screen, the option will not appear in the selection list at all.<\/p>\n
That is a meaningful trade-off. Riders who like to keep speed, battery level, and heart rate visible at all times will have to choose between a dedicated Trick Check screen and their usual data dashboard. For trick-focused riders, the dedicated screen is likely worth it; for everyone else, the old eight-second pop-up may have been enough.<\/p>\n
What eBike Flow 1.38 says about Bosch\u2019s software strategy<\/h2>\n
The timing and shape of these updates reveal more than just new features. Bosch is treating the motor as an intelligent platform, not a fixed piece of hardware. Traction control, Drivetrain Tensioner, and Trick Check were all introduced across multiple app versions, and 1.38 is the moment where those separate threads start to feel like a cohesive package.<\/p>\n
Expanding both traction control and Drivetrain Tensioner to the Cargo Line is particularly telling. It shows that Bosch is not building software exclusively for performance mountain bikers. The same motor technology that helps a rider race an enduro stage can also help a cargo bike maintain grip while hauling a week\u2019s worth of groceries up a wet driveway.<\/p>\n
For riders, the practical takeaway is simple: update the eBike Flow app to version 1.38, run through the new settings, and decide which features suit your bike. On a hardtail or cargo bike, enabling Drivetrain Tensioner is a low-risk performance upgrade. On a full-suspension bike, leave it off unless you are willing to trade some suspension compliance for directness. Traction control is worth testing on familiar terrain so you understand how the different levels feel before you need<\/a> them in an emergency.<\/p>\nThe longer arc is even more promising. With every update, Bosch is making the riding experience more customisable, more responsive, and more measurable. The hardware in the Smart System is already excellent. Update 1.38 is another step toward making the software the reason to choose one e-bike platform over another.<\/p>\n","protected":false},"excerpt":{"rendered":"
Bosch has turned its eBike Flow app into the control centre for the entire Smart System ecosystem, and version 1.38 is arguably the most rider-focused release yet. The update finally brings adjustable traction control to compatible motors, expands Drivetrain Tensioner beyond the sportiest assistance modes, and gives Trick Check a persistent home on the display. […]<\/p>\n","protected":false},"author":7,"featured_media":100413,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"fifu_image_url":"https:\/\/cards.overcentral.com\/cards\/en\/100407.png","fifu_image_alt":"Bosch eBike Flow 1.38 gains traction control and Drivetrain Tensioner","footnotes":""},"categories":[31],"tags":[],"class_list":["post-100407","post","type-post","status-publish","format-standard","has-post-thumbnail","category-technology"],"fifu_image_url":"https:\/\/cards.overcentral.com\/cards\/en\/100407.png","fifu_image_alt":"Bosch eBike Flow 1.38 gains traction control and Drivetrain Tensioner","_links":{"self":[{"href":"https:\/\/overcentral.com\/en\/wp-json\/wp\/v2\/posts\/100407","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/overcentral.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/overcentral.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/overcentral.com\/en\/wp-json\/wp\/v2\/users\/7"}],"replies":[{"embeddable":true,"href":"https:\/\/overcentral.com\/en\/wp-json\/wp\/v2\/comments?post=100407"}],"version-history":[{"count":1,"href":"https:\/\/overcentral.com\/en\/wp-json\/wp\/v2\/posts\/100407\/revisions"}],"predecessor-version":[{"id":100411,"href":"https:\/\/overcentral.com\/en\/wp-json\/wp\/v2\/posts\/100407\/revisions\/100411"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/overcentral.com\/en\/wp-json\/wp\/v2\/media\/100413"}],"wp:attachment":[{"href":"https:\/\/overcentral.com\/en\/wp-json\/wp\/v2\/media?parent=100407"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/overcentral.com\/en\/wp-json\/wp\/v2\/categories?post=100407"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/overcentral.com\/en\/wp-json\/wp\/v2\/tags?post=100407"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}