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Shimano Dura-Ace 9150 Di2 Synchro Shift: All you need to know

Stu Bowers
7 Feb 2017

Fully programmable Synchro Shift will appeal to a huge range of cyclists

Shimano has borrowed technology from its mountain bike – XTR Di2 – shift system to influence the development of its new Shimano Dura-Ace 9150 Di2. 

E-Tube (the name Shimano gives to its system platform) is the heart of the Di2 shifting, and whilst there are a few external/visual modifications that neaten things up a bit, really it’s inside, in the brains of the system, where the big changes have been made.

Synchro Shift is the most notable new feature. It’s a completely new direction, handing over the control of the shift pattern to the programmable algorithms within the system. But only if you want it to. The key message is Shimano has left everything up to the user to be able to customise the system to work optimally for their own needs.

No longer does programming entail a trip to your local bike shop either. A new wireless connection allows the user to access the system via an app (ANT private network or Bluetooth). The app software is built to be a consumer-facing product, so is simple and easy to navigate, taking you through each process in step-by-step fashion.

It allows personalisation in minutes, you can even do it mid-ride (not recommended whilst riding!) if you so desire.

Shimano Dura-Ace 9150 Di2 Synchro Shift explained 

So called ‘fully-syncro’ shifting means that a single shift lever takes control of the entire drivetrain (you can chose which buttons make the necessary operations). In this way you’re simply selecting either an easier gear or a harder gear. As you do so the system will follow a sequential shifting pattern, according to a predetermined (also user definable) configuration.

It will decide for you when it is best to make a shift between front chainrings according to the preferences you set, based on gear ratios and maintaining cadence, but will also keep you from cross-chaining unnecessarily.

It’s clearly a development aimed more at the masses than the experienced rider/racer, to take the guesswork out of what can seem like complex shifting mechanisms. Pros are not likely to be overly interested in the fully syncro mode, but the ‘semi-syncro’ might be a different story.

This will have a wider appeal to many more levels of riders. In this mode when you make a front chainring shift, the rear derailleur will automatically make a simultaneous shift (one or two sprockets, depending on your setting), in order to make the gear shift less dramatic in terms of its immediate effect on cadence/power etc.

For example, you won’t suddenly find you've spun out and scrabbling for a few extra gears if you shift from big to small chainring; the system will pre-empt this and adjust for you accordingly.

Synchro Shift: First impressions

There will no doubt be naysayers quick to lambast this kind of technology as too high tech and an unnecessary innovation for bicycles. But I would rather praise Shimano for thinking first of the mass market and the people who will really benefit from this kind of shifting assistance, and not the pros for once.

After all, they aren’t the ones buying it.

My first experiences, riding in the mountains close to Calpe, Spain, revealed that the semi syncro shifting mode appealed most of all. At first it required a conscious effort to override my own brain.

It seemed I already had an automated response to compensate for my front mech shifts with a simultaneous rear gear adjustment, such that with the system also making its own correction I was actually ending up overcompensating each time.

But once I’d re-trained that neural pathway to leave the right hand lever alone as I made a front derailleur shift, the Shimano Dura-Ace 9150 Di2 Synchro Shift system worked very well for me.

Other user definable aspects of the software include adjusting the number of sprockets the mech will shift through when you multishift (press and hold the shift button) plus the speed of shifts, and so on.

The software is really easy to navigate, and the handy part is once you’ve finished playing with your settings and found your ideals, these preferences are stored in the App so you can keep them to download to other bikes in a matter of seconds.

All that said, if this does indeed sound a bit too much, Shimano has also built in a get out clause, so users can opt to disable all Synchro Shift functions (simply select manual mode) and carry on using the gears in the way we always have.

It’s a 10 second process (that you can do from the mode button on the junction box) to switch between modes.

While we’re on the subject of the junction box….the new bar end plug version is incredibly neat. This completely does away with the old junction box (which was always a little unsightly) hanging under the stem.

With a compatible bar (i.e. one with appropriate cable ports built in) it is now possible to have all the Di2 wiring within the handlebar. The bar plug becomes the charge point too. Shimano has even thought to make a dummy plug the same to match on the other side – you can’t deny they have got the details spot on.

Garmin partnered with Shimano in the development of the new firmware, and so also has new on-screen features, such as a battery life indicator, a visual display of your gear ratios and more.

A really nice addition to the Shimano Dura-Ace 9150 shift levers is an additional button on top of the lever hood that can be used to change the modes, page swipe, stop/start Gamin etc.

But again, you decide, as every single button is programmable for whatever operation you want it to perform.

Basically it’s all about options – nothing is mandatory, so Shimano should in theory be catering for everyone and all different levels of riding experience.

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