Shimano GRX 400 vs 600 vs 820: Which Gravel Groupset (and Sandman Bike) Is Right for You?

Gravel biking has its own special demands, and Shimano answered with the GRX series of gravel-specific components. If you’re shopping for a gravel bike like our Sandman models, you’ve probably seen labels like GRX400, GRX600, or GRX820. What do these numbers mean, and how do they affect your ride? In this article, we’ll break down the technical differences in plain language and connect each groupset to the Sandman 4, Sandman 6, and Sandman 7 bikes (with handy links to their product pages). By the end, you’ll know which bike is ideal for your riding style, and we’ll even include a comparison table for easy reference. Let’s dive in!

Understanding Shimano GRX Groupsets

  

 

 

Shimano’s GRX family is built specifically for gravel and adventure riding, with features tailored for rough terrain. The numbers 400, 600, 800/820 indicate different levels (think of them like tiers of performance and price). In fact, they roughly correspond to Shimano’s road lineup levels:

 

 

 

GRX 400 series – 10-speed, comparable to the Tiagra level (entry-level, but very capable).

GRX 600 series – 11-speed, roughly equivalent to 105 (the popular mid-range).

GRX 800/810/820 series – 11-speed in the original RX800, now updated to 12-speed with RX820; comparable to Ultegra (high-end performance).

All GRX components are designed to work together and even mix with Shimano’s road parts to a degree. It’s not uncommon to see a bike mix, say, GRX600 shifters with a GRX800 derailleur. The key takeaway is that a higher number means lighter materials, more gears, and often extra features. But even the entry GRX400 delivers “outstanding performance across the range” according to reviews – so you’re getting quality at every level.

How does this tie to our bikes? We’ve matched each Sandman model with a GRX level to suit different riders:

Sandman 4 – Built on Shimano GRX400-based components (entry-level reliability), with a GRX600 crankset upgrade for wider gearing.

Sandman 6 – Equipped with a full Shimano GRX600 groupset, for smoother shifting and hydraulic brakes that elevate performance.

Sandman 7 – Top-of-the-line, featuring Shimano’s GRX820 12-speed groupset, delivering the widest gear range, premium shifting/braking, and the lightest setup.

Now, let’s look at each in detail: what technical specs do they have, and what type of rider are they best for?

Sandman 4 – GRX400 (Entry-Level Gravel Adventurer)

 

 

The Sandman 4 is our solid entry into gravel biking, and it centers around the Shimano GRX400 groupset. This gives you a highly reliable 10-speed drivetrain and proven technology trickled down from Shimano’s higher-end lines. Here’s what that means in practice:

 

 

• Speeds & Gear Range: 20 total gears (2×10 setup). The GRX400 rear derailleur (RD-RX400) manages a wide-range 10-speed cassette (we spec an 11–34T, giving easy climbing gears). Up front, we’ve paired the Sandman 4 with a Shimano GRX600 crankset in 46/30T. This 2x crank gives a 46-tooth big ring for decent speed on flats, and a 30-tooth small ring for tackling hills. The combination yields a broad range without overwhelming a newcomer. (Why a GRX600 crank on a GRX400 bike?) The GRX600 crank is compatible with the 10-speed setup and offers optimum gearing plus stiffness. It’s a small upgrade to benefit the rider with better climbing and smooth power transfer.

 

• Brakes: Mechanical disc brakes (cable-actuated). To keep the Sandman 4 affordable yet capable, it uses mechanical disc brake calipers operated by the levers. Mechanical discs are simpler—pulling a cable that squeezes the brake pads. The downside is you need a bit more hand effort and occasional adjustment as pads wear. The upside: easier maintenance (no hydraulic fluid) and lower cost. These brakes will still stop you reliably on dirt and pavement, and they out-perform old rim brakes. However, as cycling experts note, hydraulic disc brakes outperform mechanical in power and control. That’s why our higher models go fully hydraulic. For a recreational rider, the mechanical discs on the Sandman 4 are sufficient and safe, just requiring a bit more squeeze on long descents.

 

• Shifting Performance: GRX400 shifting is impressively smooth and precise, considering it’s the entry tier. You get Shimano’s proven indexed shifting with levers on the drops: click to change gears, and the derailleur quickly moves the chain onto the next sprocket. The feel is slightly more “mechanical” or solid (in a good way) compared to some pricier units which might be a touch lighter. Because it’s 10-speed, the jumps between gears are a tad larger than an 11 or 12-speed, but most riders won’t mind – it actually can make shifting choices simpler for beginners. Importantly, the GRX400 rear derailleur includes a clutch (Shimano calls it Shadow RD+), which keeps the chain taut on bumpy rides so you don’t drop your chain on gravel. This feature is shared across all GRX levels and is a huge perk for off-road stability.

 

• Weight: GRX400 parts are built a bit more burly. While we won’t bog you down with every gram, know that a GRX400 groupset might weigh a couple hundred grams more than GRX600/820. For example, the rear derailleur and shifters at the 400 level are a bit heavier (the RX400 rear mech is ~30g heavier than the 600’s). Overall, the Sandman 4 bike comes in around 9.8 kg total. It’s still very light for a gravel bike (thanks to the carbon frame), and only marginally heavier than its pricier siblings – great for long journeys without breaking the bank.

 

• Who It’s For: The Sandman 4 with GRX400 is ideal for newcomers to gravel or budget-conscious riders who still want a capable bike. If you plan to ride mixed terrain, explore dirt roads on weekends, or even commute, this bike will serve you reliably. You get trickle-down tech from Shimano’s higher groups, so you’re not missing out on functionality. As one review noted, Shimano’s mechanical GRX line offers outstanding performance even at the lower tiers – so you can confidently tackle adventures without feeling you need an upgrade. The trade-off is just slightly less refinement: the brakes require a bit more muscle and the shifting has one less gear at each end. But for many riders, especially starting out, those differences are minor. In short, Sandman 4 is your dependable gravel partner that “does it all” without frills, perfect for getting hooked on gravel riding.

Sandman 6 – GRX600 (Enthusiast-Level Performance and Hydraulics)

 

 

Stepping up to the Sandman 6, you move into the Shimano GRX600 groupset – the 11-speed, 105-level components. This bike is for the rider who wants a bit more: more gears, more refined shifting, and notably the power of hydraulic brakes. Here’s what defines the Sandman 6 experience:

 

 

• Speeds & Gear Range: 22 total gears (2×11 setup). That extra gear might not sound like much, but it gives you tighter spacing between shifts and a slightly wider range. We spec a similar gearing setup: an 11–34T cassette in back, and a GRX600 46/30T crankset in front (the same gear range as the Sandman 4, but with one extra intermediate gear in between thanks to 11-speed). The smaller steps between gears mean you can fine-tune your cadence – you’re more likely to find that “just right” gear when terrain or speed changes. Riders doing longer or faster rides will appreciate this, as you can maintain an optimal rhythm. Also, GRX600 can support even larger cassettes (up to 36T with the stock derailleur, or even 40T+ if using the long-cage variant), so it’s versatile if you ever wanted to tweak the range for big mountain days.

 

• Brakes: Hydraulic disc brakes – a major upgrade in this tier. The Sandman 6’s levers and calipers form a sealed hydraulic system. When you squeeze the lever, it pushes fluid to the caliper, pressing the pads to the rotor with greater force and modulation. The result is stronger stopping power and more nuanced control compared to mechanical brakes. On fast gravel descents or in wet/muddy conditions, you’ll feel the difference: braking requires less effort and you get a better feel for how much grip you have. Another benefit is reduced maintenance duringrides – hydraulics self-adjust as pads wear, so the brake feel remains consistent (no need to tighten cables on the fly). Shimano’s GRX hydraulic brakes are known to be excellent – they’re essentially using Shimano’s proven road disc brake tech, which earned high praise for power and reliability. One small note: only the top-tier GRX levers get a feature called Servo Wave (borrowed from mountain bike tech) which changes leverage for even more bite early in the pull. The GRX600 brakes don’t have Servo Wave, but in practice you still get terrific braking and most riders won’t miss that extra bit of tech in day-to-day riding. In short, on the Sandman 6 you can charge downhills or corner with confidence knowing you have ample, controllable braking power at your fingertips.

 

• Shifting Performance: GRX600 brings 11-speed mechanical shifting that’s incredibly reliable and crisp. Many compare GRX600 to the Shimano 105 road groupset (which is famed as the workhorse of cycling). The shift levers on Sandman 6 are GRX ST-RX600 units, which have a very similar shape and feel to 105 levers but are tuned for gravel use. They have a textured surface and a curve designed for better grip when you’re bouncing on rough roads. Shifts with GRX600 are a tad lighter and faster than GRX400, thanks to improved derailleurs and shifter internals. It’s not an electronic shift or anything fancy – it’s still cable-actuated – but it feels refined. Under load (like climbing while shifting), 11-speed Shimano has a reputation for smooth gear changes with minimal clunk. And remember, you still have the chain stabilizer clutch in the rear derailleur, same as GRX400, keeping things quiet and secure. In essence, GRX600 shifting gives you that “buttery” feeling people love about Shimano 105: you click, it obeys, no fuss. This level is often favored by avid riders because it offers nearly the same performance as the top-tier, with only minor weight penalties.

 

• Weight: With GRX600, the bike sheds a little weight in components. The crankset, for example, is slightly lighter and the rear derailleur uses some lighter materials than the GRX400 equivalent. While the difference is not night-and-day, you might save on the order of 100–200 grams going from 400 to 600 level parts. The Sandman 6 complete bike still comes in around 9.8 kg (similar to the 4, since we share the crank and other parts). Where you really save weight is compared to bikes that might have alloy frames – our carbon frame plus GRX600 keeps it very competitive. Also, losing that extra gear cable and gaining hydraulics doesn’t change much weight-wise (the hydraulic fluid and hoses are about the same as cable and housing). The bottom line: weight isn’t the primary reason to choose GRX600; it’s chosen for performance, but it still keeps the bike nice and light for its class.

 

• Who It’s For: The Sandman 6 is great for enthusiast gravel riders and those who plan to tackle more demanding terrain or longer rides. If you’re the kind of rider who is out every weekend exploring backroads, signing up for gravel events, or you simply know you appreciate quality gear, the GRX600 level is a sweet spot. It gives you a taste of high-end performance without the premium price of top-tier. The hydraulic brakes alone are a big reason to move up to the 6 if you’re serious about mixed-terrain riding – you’ll appreciate the extra assurance on technical sections. Also, if you’re an all-weather rider, hydraulics tend to perform better in mud and rain. The shifting and extra gear make the Sandman 6 feel a bit more “expert”, allowing you to maintain cadence on varied terrain efficiently. However, it’s still user-friendly and not overly finicky. In short, the Sandman 6 is for the rider who’s committed to gravel adventures or bikepacking, and wants a bike that can keep up as their skills and ambitions grow. It’s reliable enough for daily use, yet capable enough for the occasional race or endurance challenge.

Sandman 7 – GRX820 (Premium 12-Speed Gravel Racer)

 

At the top of the lineup sits the Sandman 7, featuring Shimano’s flagship GRX820 groupset. This is Shimano’s latest 12-speed mechanical gravel group, analogous to a high-end Ultegra-level system but tuned for gravel. The Sandman 7 is all about delivering the best performance: the most gears, the lightest weight, and the most refined feel. Let’s break down what you get:

 

 

• Speeds & Gear Range: 24 total gears (2×12 setup). Yes, you read that right – the GRX820 brings 12-speed gearing to gravel. On the Sandman 7 we’ve configured it as a 2x, with a 48/31T GRX820 crankset paired to an 12-speed 11–34T cassette. This setup provides the widest range and the smallest steps between gears of any Sandman model. You get a high gear (48×11) suitable for sprinting on pavement and a very low gear (31×34) for winching up steep gravel climbs. The jumps between cogs are very smooth, meaning you can always find an ideal cadence. Going from 11-speed to 12-speed doesn’t dramatically expand the range (we kept similar end points) but it sneaks an extra gear in, so you rarely feel “I wish I had an in-between gear.” Riders who are sensitive to cadence or do a lot of varied terrain in one ride will love this. Moreover, the GRX820 drivetrain benefits from Shimano’s latest Hyperglide+ technology (inherited from their top MTB groups). This means shifting, especially to an easier gear under power, is remarkably smooth and quick – the chain and cassette are engineered to mesh in a way that reduces the hesitation or clunk when you shift while pedaling hard. In short, the GRX820 gives you pro-level gearing: race-ready and adventure-ready at the same time.

 

• Brakes: Hydraulic disc brakes (Servo Wave-equipped). At the GRX820 level, Shimano includes all the bells and whistles in the brake system. The ST-RX820 brake levers have Servo Wave action, which means the brake pads engage quickly with a light pull, and then the leverage increases for greater power as you pull further. This yields outstanding modulation – gentle feathering or hard stops on demand. The calipers (BR-RX820) use Shimano’s top-grade materials (like ceramic pistons for heat resistance, a step up from the resin pistons in lower tiers) and come stock with Ice-Tech finned brake pads for heat dissipation. The result is brakes that can handle long mountain descents without fading and offer a very consistent feel. On a gravel bike, this is confidence-inspiring, especially if you’re tackling alpine passes or riding with bikepacking gear downhill. Even if you’re not pushing those extremes, the GRX820 brakes just feel nice – a touch more crisp and powerful than the GRX600 set, though both are excellent. Essentially, you get the same level of braking performance that a high-end road racer or mountain biker would expect: maximum power, minimal weight, and high durability. For the rider, it simply translates to no worries about your stopping power in any conditions.

 

• Shifting Performance: GRX820’s shifting is as good as it gets for mechanical drivetrains. With 12-speed, the tolerances are tighter, and Shimano engineered the new levers and derailleurs to handle that precision under rough use. Reviewers have noted that the shifting action on the 12-speed GRX feels “smooth through the dozen gears” with a reassuring, high-quality mechanical feel (no cheap clacking). It’s the kind of crispness that one expects from top-tier components – each shift is quick and positive. The front shifting (moving between the 48T and 31T rings) is also very good; Shimano has a long history of making the best front derailleurs in the business. Even though 17 teeth is a big jump, the GRX front derailleur handles it without complaint, trimming as needed to avoid chain rub. If you’re coming from an 11-speed setup, you might not notice a huge difference in how the shifting feels (Shimano was already great), but you’ll notice it never misses and it’s slightly quieter and more precise under load. The levers on GRX820 are nicely textured and ergonomically shaped for gravel. And as mentioned, they also have an extra feature: on GRX800/820, Shimano allows you to adjust the “free stroke” (basically the idle gap) of the brake lever a bit – this is a small tweak for personal preference on brake feel, which the 600-level levers lack. It’s not a game-changer, but it shows the level of fine-tuning available at the top end. All in all, if you want the pinnacle of traditional (non-electric) shifting on a gravel bike, GRX820 delivers. Many riders describe it as “set and forget” – once tuned, it stays crisp for a long time with minimal adjustment, even after rough rides, thanks to high-grade sealed cables/housing and that chain stabilizer keeping things orderly.

 

• Weight: One advantage of GRX820 being the premium tier is lighter weight components. The crankset, for example, uses Hollowtech II construction with lighter alloy – it weighs significantly less than the GRX600 crank (the previous GRX810 crank was ~100g lighter than the 600, and the new one continues that trend). The shifters and derailleurs also shave some grams with composite or alloy pieces. All told, a full GRX820 2x groupset will weigh a few hundred grams less than the GRX600 equivalent. On our Sandman 7, the total bike weight is around 9.6 kg, the lightest of the trio. That’s partially due to the groupset and also a few other upscale touches. A couple hundred grams may not be hugely noticeable in riding, but if you’re lifting the bike over gates or shouldering it on a run-up, you’ll appreciate any savings. More importantly, less weight in the components often contributes to a snappier, responsive feel when you pedal or flick the bike around. The Sandman 7 feels almost effortless when accelerating, thanks to both the light frame and the light drivetrain parts. For riders eyeing competition or long-distance events, this weight savings can add up over hours of pedaling.

 

• Who It’s For: The Sandman 7 is aimed at serious riders, racers, or anyone who wants the very best and is willing to invest in it. If you’re the rider doing epic gravel races (like Unbound, Belgian Waffle Ride, etc.), or you simply demand top performance on your weekend rides, the GRX820-equipped Sandman 7 is your dream build. It’s also the bike for the tech enthusiast – the one who appreciates having cutting-edge features (12-speed drivetrain, advanced brakes) and maybe has an eye on future upgrades (the GRX820 is so high-end that the only “upgrade” path Shimano offers above it would be electronic shifting, which is a whole different level of expense). That said, you don’t have to be a racer to enjoy the Sandman 7. Even if you’re a recreational rider, you might prefer the premium feel – the light action of the controls, the refined ergonomics, and knowing that the bike will not be the limiting factor in your adventures. It’s a bike that can do it all: fast group rides, multi-day bikepacking, or rugged gravel grinding, all with a smile. The honest truth about trade-offs: aside from higher cost, there aren’t many downsides to GRX820. It’s as close as it gets to “no compromise.” The only caveat we’d note is that a 12-speed system can be a tad more finicky to adjust if it gets out of tune (simply because more cogs packed in means less margin for error), but Shimano has engineered this so well that it’s rarely an issue once set up. In summary, choose Sandman 7 if you want top-tier performance and plan to push your gravel riding to the limits – or if you simply love having the best gear and the confidence that comes with it.

Which Sandman to Choose? Making Your Decision

Now that we’ve detailed each model, let’s step back and compare. All three Sandman bikes share the same core: a lightweight carbon frame, gravel-optimized geometry, and quality components. No matter which you choose, you’re getting a capable gravel machine. The differences come down to the groupset level – and thus the ride experience and long-term ownership experience. Here are some pointers to help you decide:

• Budget vs. Performance: If budget is a big factor, the Sandman 4 (GRX400) offers tremendous value. You get essentially 80-90% of the performance of the higher models in terms of functionality, with cost-saving in the brakes and a bit less high-tech finish. It’s perfect if you’re just getting into the sport or don’t feel the need for bells and whistles. However, if you can stretch a bit, the Sandman 6 gives you hydraulic brakes and a more polished drivetrain, which are worth it for frequent riders – it’s the sweet spot for most enthusiasts. The Sandman 7 is for when only the best will do (and naturally comes at a higher price); it’s an investment in a bike that likely won’t need any upgrades for a long time.

 

• Your Riding Terrain and Style: Think about where and how you ride. Do you ride lots of steep hills or carry gear? All three have low gearing, but the 11-speed and 12-speed will give you more options to maintain cadence on climbs. Do you ride fast group rides on gravel or mixed surfaces? The tighter gear steps and extra high-end gear of the Sandman 7 might appeal if you’re trying to keep up on flats or sprints. If you ride in a lot of mud or dust, hydraulic brakes (Sandman 6 and 7) cope better as they’re sealed – mechanical brakes might need more cleaning and adjusting in between. If your rides are more leisurely explorations on rail-trails or mellow dirt roads, the Sandman 4 is probably all you need; but if you seek out technical trails or long alpine descents, the Sandman 6 or 7’s superior braking and ultra-stable shifting will shine.

 

• Future Plans: Are you the type who upgrades components or keeps a bike for many years? The Sandman 6 and 7 give you a bit more future-proofing. For instance, 12-speed is the new standard Shimano is moving toward; with Sandman 7, you’re on the cutting edge. With Sandman 6’s 11-speed, you’re on a standard that will be common and supported for years (105 and older Ultegra are 11-speed). The Sandman 4’s 10-speed is still very common (Tiagra-level) and perfectly fine, but it is one generation behind what new higher-end bikes are using. All will be serviceable long-term, but these are considerations. Also, if you think you might want to go electronic shifting eventually, starting at a higher level might make that switch easier down the road (though it would be a big change). On the flip side, if you’re not sure gravel riding is for you, it might make sense to start with the Sandman 4 and upgrade later once you’ve fallen in love with the sport – the frame is the same high quality, so you could conceivably install a hydraulic brake set or 11-speed shifters later on as a project.

 

• Ride Feel: It’s worth noting the intangible: the higher-tier bikes have a slightly “snappier” feel. Test riding them back-to-back, an experienced rider would notice the Sandman 7 feels the most refined – almost like the bike disappears beneath you, reacting instantly to input. The Sandman 4 might feel a little more utilitarian – not in a bad way, but you feel the mechanical nature a touch more (e.g., a bit more lever effort here, a bit more chain noise there). The Sandman 6 is right in between, balancing smoothness and feedback. None of these bikes are “sloppy” by any means; they all benefit from the stiff carbon frame and quality wheels. It’s just that as you upgrade, the components polish off more of the rough edges. This can contribute to overall comfort and confidence on long rides – less effort to shift and brake means less fatigue.

To summarize, Sandman 4 is best for beginners or casual riders, Sandman 6 suits regular riders who crave better brakes and shifts, and Sandman 7 is for devoted gravel grinders and racers. Whichever you pick, you’re getting a bike that can handle the chaos of gravel and keep you smiling.

Below is a quick comparison table to highlight the key differences and help you make a final decision at a glance:

(All models share: Carbon frame & fork (Toray T800), Rinos carbon handlebar, carbon seatpost, 700×40c gravel tires, and thru-axle disc wheels. So the core difference is in the Shimano groupset components and what they bring to the ride.)

We hope this breakdown of Shimano GRX400 vs 600 vs 820 (and our Sandman models) helped clear up the differences. Gravel biking is about freedom and adventure, and whichever model you choose, you’ll be well-equipped to “leave the smooth pavement behind” and embrace the gravel grind with confidence. If you have more questions or want to test ride these bikes, don’t hesitate to reach out or visit us – we’re here to help you find your perfect gravel companion. Now, it’s time to gear up and hit those dusty roads. See you out there on the gravel!