Like this site? Help us to make it better.


Is Shimano 105 Di2 a good gravel groupset?

Shimano recently launched its first 105 Di2 groupset. But is it any good for a gravel bike? Let’s find out

Gravel bikes are quite capable machines and people use them in many different ways. That leads to some people fitting road components to their gravel bikes and if that suits your needs then that’s fine with us. But what about using a road groupset on a gravel bike? Would 105 Di2 be any good, for example? 

Is the system robust enough?

Matthieu van der Poel Canyon Inflite Worlds 2-2

As soon as Shimano’s electronic Di2 gears were introduced back in 2009, there were fears that the groupset would fall to pieces at the mere sight of a bit of water or mud. But Dura-Ace quickly gained popularity among the pro peloton and cyclocross riders put it to the ultimate test with a combination of mud, sand, snow and jet washes. It survived and Di2 has been perfectly happy to tough it out in the harshest conditions ever since.

The latest 105 Di2 is no different, surviving Dave’s rigorous testing as part of his Orro Terra C review which will be on the site very soon. 

In fact, we find that Di2 is absolutely brilliant in the muddiest conditions as the motor is pushing the derailleur equally in both directions, rather than relying on spring tension as you’d get with a mechanical derailleur.

So we’d have no second thoughts about using this groupset in typical gravel conditions.

Brains in an un-brainy place

Moda Finale Shimano 105 Di2 - rear mech rear.jpg

One thing we would say, however, and this is a complaint to level at all of Shimano’s 12-speed Di2 road groupsets, is that the brains of the system are housed in the rear derailleur. 

Essentially, Shimano has made the rear derailleur the control centre for the new groupset, packing the shift signal receiver, Bluetooth communicator and a few other bits into the derailleur body. This then connects, via a wire, to the battery and then runs to the front derailleur.

> 33 bikes that feature Shimano’s new 105 Di2 groupset

But derailleurs have always been an exposed part of the bicycle and they are generally the 1st to take a hit in a crash so what's the problem? With all of the brains of the system being packed into the rear derailleur, it has become the most expensive component within the groupset. That means that if you slide out in a corner, come down in a sprint finish or simply get ridden into by another rider, you could have a very expensive repair bill.

We do wonder why the clever bits weren’t simply bolted onto the battery which are, these days, hidden away inside the frame or seatpost. Anyway, if you wreck a rear derailleur, be prepared for it to be a very costly day on the bike.

Will it fit on my gravel frameset?

2020 Specialized Diverge chainstay skinny - 1

There is one slight potential issue that you might run into if you decided to slap this groupset onto your gravel bike and that is that it might not actually fit. Take a gravel bike like the Specialized Crux. It isn’t unique in being designed to accept only certain chainsets and there’s a very good reason for that.

The Crux uses a solid section in the driveside chainstay to maximise tyre clearance, which adds versatility to the bike. Doing this means that there is a limit to the size and position of the chainrings that you can use.

For 2 X systems, you might need to use a gravel-specific chainset as these are spaced wider and come with smaller chainrings. As the 105 chainset is only available in a 50/34 combination, it might not fit, so check with the frameset manufacturer before you go buying this groupset.


2022 Shimano GRX silver - rear mech detail.jpg

One key feature that you won’t get on the 105 Di2 rear derailleur is a clutch system. This is something that you’ll find on Shimano’s gravel and mountain bike rear derailleurs and they’re very useful for limiting chain slap.

Aside from the noise reduction, preventing chain slap can also help to protect your poor chainstay from damage and it is said to reduce the likelihood of dropping a chain.

Gearing is the deciding factor

Really though, the deciding factor will be whether the gearing is suitable for the riding that you want to do. Gravel bikes generally come equipped with some very easy gearing to help you ride up steep slopes on loose surfaces.

> Shimano 105 R7100 Di2 Groupset

Take that Crux. On it, you’ll find a 10-44T cassette and a 40T chainring. The easiest gear that creates is a 25.44 inch while the largest is a 111.81 inch gear. If you installed Shimano’s 105 Di2 system, with the 11-36T cassette and the 50/34T chainset, you’d have an easiest gear of 26.28 inches and a hardest gear of 127.19 inches.

If you haven’t nodded off, that means the gravel groupset on the Crux is going to give you an easier gear to turn while you try to pick your way up the technical climb that has always given you trouble.

At the other end, you’re getting a much bigger hardest gear which will allow you to go faster when the situation allows. 

Which one is best for you?

Moda Finale

That largely depends on the riding that you’re intending to do. If you plan on riding some very chunky gravel with steep, technical climbs and tracks that aren’t that fast, then you’re going to be better off with a gravel-specific groupset. Dave says that 105 Di2 would really benefit from a sub-compact chainset offering, though we’re unlikely to ever see one.

But if your gravel riding takes place on large gravel fire roads, places like Salisbury plain or you’ve got a lot of road riding to do to take in your gravel, then 105 Di2, with the relatively close spacing on the cassette, is going to give you the top-end gears and small cadence changes that you’ll need.

> Shimano 105 Di2 vs SRAM Rival eTap - Which is better?

So, would we go out and buy Shimano’s 105 Di2 groupset for a gravel bike? For an all-road bike, it’d be fine, but due to the lack of truly low gears, we’d stick with GRX for an adventure gravel machine.

Add new comment


Nixster | 1 year ago

The lack of a sub compact chainset option could be readily solved by binning the lardy 105 item and going with either Rotor or Praxis. Not so cheap but definitely more cheerful.


HaveLegsWillRide | 1 year ago

I had old 5800 105 on a commuter I also used for "soft-roading". I ended up swapping to a gravel frame as I really needed some extra tyre clearance to stop me killing my rims. Apart from front mech & caliper mounts it was a straight swap, but I started suffering loads of dropped chains. Frame manufacturer recommended trying a GRX rear mech for the clutch feature (even though the 105 had previously been fine), which didn't solve it. I ended up going down the wider GRX front mech/chainset route, and it's worked perfectly since. Short version, the chain line a frame is designed around was an issue for 105 working for "gravel". If my old frame had wider tyre clearances this could have been a very different post! Saying that, the 46/30 gearing (especially with a 34 cassette) is awesome for border line MTB terrain & with a 30 it's fine as a road bike still.

kil0ran | 1 year ago
1 like

I know 12sp chains are thinner but is there that much of a difference between 11 & 12sp when it comes to chainrings? I think I'd be tempted to try it with the GRX 46/30 (or one of the subcompacts from Miche or FSA)

mark1a replied to kil0ran | 1 year ago

The compatibility issue I found with GRX was chainline related. My gravel bike (2018 Diverge) came with 5800 105, predating GRX. I wanted more flexible gearing as it was too road focussed, great for New Forest fire trails but not so much in West Dorset closer to home. The GRX chainrings are IIRC 2.5mm further outboard, so I ended up changing both mechs to get 46/30 on the front and 11/34 on the back. Good news was of course that GRX is compatible with road shifters so saved money keeping the cockpit intact. 

Xenophon2 | 1 year ago

I've never been a fan of Shimano's Di2 solution.  It's wireless...with a wire.  Dunno, never could get over that.

Went from 11-sp mechanical shifting to SRAM 12 sp etap-axs rival.  Which I of course don't really need nor can fully exploit but that's another issue.  OK, so you need to click out the battery from the derailer once every 800 km and recharge it.  Not a big deal, keep a loaded spare in the toolkit and you're safe.  Shifting is simply perfect, a lot smoother and faster than mechanical.

I ride mixed road/gravel, didn't want a 2x solution and found the jumps on a 10-44 too large, on the road I had the feeling of never being in quite the right gear.  My solution was to stay with a 11-34 cassette and throw down a healthy chunk of cash for a Classified internally geared hub that gives me (with a 42 T chainring) the equivalent of a 29.  All I ever needed.

IanMSpencer replied to Xenophon2 | 1 year ago

I was exploring the tech specs and parts, because I was surprised to see a junction box in the handlebar end of a GRX 1x12 Di2 setup.

The wireless bit is optional, 12 speed can still be fully wired with alternate shifters.

Your post suggests that Di2 was half wireless for some time, wireless was only introduced with the 12 speed. With battery in seat tube and access along the chain stay, the wiring remaining is simple and allows for reliable connection between front and rear derailleur which allows for trimming and reliable power supply. Those SRAM batteries are quite expensive and also prone to damage, the clips snap off.

kil0ran replied to IanMSpencer | 1 year ago

The problem though is that on some bikes the driveside chainstay is solid or a welded in plate to avoid having a dropped chainstay there, so routing would need to be external. Have a look at the Planet X Tempest as an example.

IanMSpencer | 1 year ago
1 like

I've suggested an answer as to why the brains are in the derailleur before.

The wireless receiver needs to be designed to be outside the frame because Shimano cannot guarantee that the frame will not interfere with the signal. As soon as you need some chips on a PCB in a component outside the frame, you are looking at front or rear mech or an extra device. An extra device to hold the brains would need somewhere to live - previously, add-ons were up in the handlebar area (a place we are trying to avoid wires to), there aren't any obvious places elsewhere, so avoiding frame design changes to accomodate the groupset it end up being front or rear derailleur.

Front derailleur is a no-go because... not all groupsets will have a front derailleur. So rear derailleur it is, and there is no benefit in splitting the electronics, the manufacturing cost of putting just the receiver in the deralleur and then having some transmission through to the computer in the battery would require additional electronics, so the manufacturing cost of sticking it in the rear derailleur is going to be the cheapest solution (especially given that there is already a need for electronics there to operate the motor)..

Looking at Di2 prices for RDs, the old 11 speed derailleurs without control electronics were still pretty pricey, it is hard to say just how much of the price increase is due to additional electronics and how much is just inflation. Compared with a dumb Di2 rear changer, they are just horribly expensive parts compared with a cable operated RD. Front derailleur prices are similarly inflated between 11 and 12 speed, so I don't think that the electronics are really part of the price problem, given that the front derailleur is essentially the same with both 11 and 12 speed.

pmurden | 1 year ago

I've got 105 on my 2015 Cube cross bike and it's pretty much survived all kinds of off roading thoughout this time.

Adam Sutton replied to pmurden | 1 year ago

Same, though the chain does slap about a fair bit on the rough. Never had the chain actually come off due to this though.

Secret_squirrel replied to Adam Sutton | 1 year ago

For an alternative view. I had the misfortune to bin my GRX DI2 equipped bike  with just scuffs to shifters and bruises to me and 3 weeks later the rear mech packed up..... 200+ quid later.....

OnYerBike replied to pmurden | 1 year ago

The "robustness" in this article refers primarily to the fact that the Di2, being electronic, might be more susceptible to issues arising from water ingress etc.

Secret_squirrel | 1 year ago

Its worth noting that if Shimano allowed you to mix 11 speed and 12 speed DI2 (at least for GRX shifters and front mech - which would be eminently possible) you could run with a GRX front mech, rings and crank and get 30x36 as your lowest gear with the 46/30 chainset.  Not sure how much narrower the 12 speed chains are though....

Latest Comments