Road Cycling

2023 Trek Domane+ e-road bike review: Ultra-quiet, ultra-stealthy – CyclingTips

Trek has today announced the third generation of its Domane+ e-assist road bike, and it’s quite the change from the one that came before. There’s a new motor from German company TQ, a brand-new carbon fiber frame with more advanced carbon fiber content and construction, more tire clearance, and in general, a sleeker and lighter total package that looks and feels more like a “regular” road bike.

It sounds like quite the complete package on paper, and it mostly is in reality – with some caveats, of course. 

The lightning pace of e-bike motor development 

Trek clearly isn’t shy about switching motor suppliers. Each generation of the Domane+ has used a different brand of motor: Bosch on the first generation one, Fazua on the second iteration, and now TQ on this latest third-generation model. 

Why the switch, you wonder? Because it seems like quite the advancement in a number of key areas.

First and foremost, the TQ HPR-50 motor is legitimately tiny, so much so that in profile, you almost wouldn’t guess at all that the Domane+ is an e-bike. Unlike the previous Bosch and Fazua units, the TQ is hidden completely inside a painted-to-match shroud at the bottom bracket with little on the outside to give anything away. Of course, a closer look reveals clues such as the cooling port on the underside of the cover, but even the battery is fully integrated inside the down tube.

The TQ HPR-50 motor is shockingly small, and remarkably quiet.

Trek is also touting the HPR-50’s unusually quiet operation, which comes about thanks to a unique interior configuration that does away with the usual array of reduction gears and/or belts, and is claimed to reduce internal friction, too. Trek’s official press materials also make mention of the lower Q-factor as compared to the Fazua unit, but don’t get too excited; it’s only down 2 mm in total, and the 163 mm figure is still about 12 mm wider than what you get with Shimano GRX, or 17 mm wider than most dedicated road cranks. 

Be that as it may, the specs of the TQ HPR-50 motor are impressive. The official maximum power output is 300 W (or 50 Nm of torque), and it’s powered by a 360 Wh Li-ion battery in the down tube that Trek claims is good for “up to” 145 km (90 miles) in Eco mode. An optional range extender battery tucks into a water bottle cage for another 160 Wh, and the system can even run on just the range extender battery alone should you want to fly with your new Domane+ and need to tuck in under typical airline battery size restrictions.

Three levels of e-assist are available, each of which can be customized using the Trek Central smartphone app. Switching between the three assist levels is literally at your fingertips thanks to convenient remote buttons positioned next to the brake lever hoods, while the various mode screens on the high-resolution LCD panel on the top tube are accessed directly on that panel. Among the available screen pages are windows for remaining battery life (expressed numerically as both a percentage and time to empty, and visually with bars), current power output, speed, and distance – and when you’re charging the system, the display even gives you a precise countdown to when the battery is full. 

Frame design implications

The bigger benefit of switching to the TQ HPR-50 motor is arguably how it affects the latest Domane+’s frame design. Trek sought to have this version look as much like a non-powered bike as possible, and aside from some generally inflated proportions, that goal seems to have been met.

The motor’s smaller form factor makes for a more normal-looking bottom bracket area, and although the down tube is notably bulbous given the internally housed battery, the whole frame looks surprisingly proportional. The Q-factor may not have changed much, but the more typical chainline has allowed Trek to switch to a standard 142 mm-wide rear hub in place of the “Road Boost” 148 mm one on the previous-generation Domane+, which is a great move for wheel compatibility.

The down tube may be enormous, but it looks less out of place nowadays given how big they’ve gotten on modern aero bikes.

The 2023 Domane+ marks the first time Trek has used its top-end OCLV 800 carbon fiber content. Combined with the integrated down tube battery – meaning there’s no need for a large hatch – Trek claims to have lopped 450 g from the previous Domane+ chassis. Claimed weight for an unpainted 56 cm frame is around 1,250 g. Adding to that is 1,850 g for the motor, 1,835 g for the 360-Wh battery, plus a few more grams for mounting hardware.

That claimed frame weight includes the latest version of Trek’s IsoSpeed pivoting seat cluster concept. This incarnation isn’t adjustable, but it does use a conventional (albeit proprietary) telescoping carbon fiber seatpost instead of the integrated seatmast of previous IsoSpeed-equipped bikes. 

All in, my 52 cm flagship sample with a SRAM Red eTap AXS wireless electronic 1×12 groupset and Bontrager Aeolus RSL 37V carbon clinchers tips the scales at a comparatively svelte 12.21 kg (26.92 lb).

Trek isn’t touting the new Domane+ as an aero bike, but it still bears a lot of aero cues.

Save for a 10 mm increase in chainstay length – a consequence of the TQ HPR-50’s motor casing size – frame geometry is the same as the non-powered Domane, down to the millimeter. Stack and reach figures are more upright and relaxed as compared to the Madone or Emonda, but both are still pretty sporty overall, and trail figures in the low-60s across the board are intended to provide fairly nimble handling manners. 

Despite those virtually identical dimensions, the Domane+ is approved for tires up to 40 mm-wide, whereas the non-powered Domane tops out at 35 mm. Keep in mind those are Trek’s official ratings, which account for a minimum of 6 mm of space all around. Actual maximum tire sizes will almost certainly be bigger, though that’ll depend on your comfort level for potential frame rub. 

Frame geometry of the new Domane+ is virtually identical to the standard Domane, almost down to the millimeter. The only exception is the chainstays, which are 10 mm longer on the e-bike version. Photo: Trek Bicycle Corporation.

Either way, adding fenders to the hidden front and rear mounts will drop that maximum tire size by 5 mm. 

Naturally, cabling is fully hidden, although the manner in which Trek has gone about it for the new Domane+ isn’t nearly as maddening as it could have been. Lines are run externally on the handlebar before being routing alongside the underside of (not through) the stem and then into ports in the dedicated upper headset cover. Keeping things visually tidy are a cosmetic cover bolted to the bottom of the stem and profiled headset spacers that are also split for easier bar height adjustment. 

Models, availability, and pricing

Trek will offer the new Domane+ in six different build kits, all using the same frame and motor package. There are only three price points, though, with each one offering a SRAM and Shimano variant. Interestingly, all SRAM-equipped bikes will come with 1×12 drivetrains and 40 mm-wide Bontrager gravel tires, while Shimano bikes are set up with 2×12 drivetrains and more tarmac-oriented 32 mm-wide slicks. As usual for Trek’s premium models, Project One custom builds are available in most models, although whichever way you slice it, the prices are awfully high.

Topping the list is the Domane+ SLR 9 eTap P1 (US$13,000 / AU$n/a / £12,900 / €14,500), built with a SRAM Red eTap AXS 1×12 electronic groupset, 25 mm-wide Bontrager Aeolus RSL 37V carbon clinchers, and 40 mm-wide Bontrager GR1 Team Issue gravel tires. Claimed weight is 12.15 kg (26.79 lb).

Sitting alongside that is the Domane+ SLR 9 P1 (US$13,000 / AU$n/a / £12,500 / €14,000), equipped with a Shimano Dura-Ace Di2 2×12 electronic groupset, 21 mm-wide Bontrager Aeolus RSL 37 carbon clinchers, and 32 mm-wide Bontrager R3 Hard-Case Lite slicks. Claimed weight is 11.75 kg (25.90 lb).

The middle child is the Domane+ SLR 7 eTap P1 (US$10,000 / AU$n/a / £9,750 / €11,000) with a SRAM Force eTap AXS 1×12 electronic groupset, 25 mm-wide Bontrager Aeolus Pro 3V carbon clinchers, and 40 mm-wide Bontrager GR1 Team Issue gravel tires. Claimed weight is 12.50 kg (27.56 lb).

Alternatively, the Domane+ SLR 7 P1 (US$10,000 / AU$n/a / £9,450 / €10,600) comes with a Shimano Ultegra Di2 2×12 electronic groupset and the same wheel-and-tire package. Claimed weight is 12.20 kg (26.90 lb).

There’s also a slightly less expensive non-Project One Domane+ SLR 7 (US$9,500 / AU$14,500 / £8,900 / €10,000).

Looking for the fancy TQ motor on a “budget”? The Domane+ SLR 6 eTap P1 (US$9,000 / AU$n/a / £8,900 / €10,000) is equipped with SRAM’s Rival eTap AXS 1×12 electronic groupset, 25 mm-wide Bontrager Aeolus Pro 3V carbon clinchers, and 40 mm-wide Bontrager GR1 Team Issue gravel tires. Claimed weight is 12.60 kg (27.78 lb).

If you prefer Shimano, there’s the Domane+ SLR 6 P1 (US$9,000 / AU$n/a / £8,890 / €9,600) with the same wheel-and-tire package, but Shimano’s latest 105 Di2 2×12 electronic groupset. Claimed weight is 12.40 kg (27.34 lb).

Finally, there’s the non-P1 Domane+ SLR 6 (US$8,500 / AU$13,000 / £8,340 / €9,000).

All of the new Domane+ models are supposedly available for ordering and/or purchase starting today.

Like an ever-present hand on your back

I should first point out in this review that your own experience on the new Domane+ will vary greatly depending on where you are. In the US, the TQ HPR-50 motor is allowed to operate at full power up to 45 km/h (28 mph). However, the cutoff in Europe is just 25 km/h, while most other countries will be at various points in between. I did this test in the United States, so take my commentary with a grain of salt if you live in a different region. 

It’s also important to remember that there are essentially two major categories these days: so-called full-power ones such as what you normally see from brands like Bosch and Shimano, and lightweight models such as this new Domane+. Full-power ones are usually rated for around 250 W or so of power (and around 85 Nm of torque), but keep in mind that’s a nominal figure. Peak outputs are usually much, much higher – often more than 800 W. 

But like other e-bikes in this “lightweight” category, the output of the TQ HPR-50 motor is far more modest. It’s rated at 300 W, but that’s the most you’ll ever get out of it (give or take a few watts). Likewise, maximum torque is capped at 50 Nm. The benefit of that reduced output is a huge weight advantage for the motor and battery itself, plus everything else on the bike can be made lighter as well.

The head tube area is big and boxy, but it doesn’t appear as such since it’s in proportion with the rest of the front triangle. Hidden cabling cleans things up, too.

That all said, while I know opinions are definitely mixed out there with respect to e-road bikes, I’d be lying if I said I didn’t have one heck of a good time testing this thing.

Those full-power e-bikes are undoubtedly fun (so much power!), but the experience can also be so far removed from purely human-powered pedaling that it can almost seem like something other than bike riding. But this Domane+? It’s more like you’ve always got a hand on your back, or the feeling you get when you’re having a really, really (really) good day. 

Trek intends for the Domane+ to feel like a regular road bike, and for the most part, I’m inclined to agree. Power from the TQ motor doesn’t come suddenly like a kick, but more like a building wave. It’s surprisingly subtle, so much so that when you rise out of the saddle to sprint, it almost seems like nothing’s happening – but then you look at your speed and your times, and it’s pretty clear that isn’t the case.

The high-resolution display is easy to read in bright sunlight and offers plenty of usable information across its multiple pages. And whatever brain is hidden inside this thing to meter out the power seems pretty darned smart.

The way that power comes on is interesting, though. It’s not simply a direct proportion of your own output, but a more complex calculation that also takes other factors into account like speed and cadence. From what I can tell, it’s almost like the system has two goals.

One is helping you maintain your speed. For example, when casually cruising at 150 W (and with the highest-power setting selected), there are times the system is putting out 200 W or more. At other times, it’s kicking out almost nothing. But in either case, how much power the system produces depends on how much help it thinks you need, and it does an uncannily good job of figuring that out. 

It’s also pretty impressive when flirting with that 45 km/h cutoff. One of the main drags heading back into town is mostly flat, but with some small rollers and often just enough of a tailwind that you can really build a head of steam. The Domane+ was more than happy to give me a nudge to get me to that magical 45 km/h mark, and then just barely enough power to let me stay just shy of that figure so as to not trigger the cutoff. And when I did cross that line, the cutoff is remarkably gentle, so much so that I kept peeking at the top tube display to see if the system really wasn’t doing anything.  

There’s an awful lot of carbon fiber in this image.

It’s when climbing that the TQ HPR-50 comes into its own. There, the motor doesn’t seem to just want you to maintain your speed; it wants you to feel like a superhero (at least in full-power mode). Needless to say, the feeling of climbing like that is addictive, but it also highlights the power limitations of the system. Say you’re climbing steady at 200 W and the system is kicking out another 300 W. But if you put down more than that, it’s still topped out at 300 W. Granted, that’s still an awful lot more than I can maintain on my own, but proportionally speaking, it’s more noticeable that the system is cutting power than when you’re hitting the speed limit. 

But it’s still fun.

Unfortunately, there’s another limit to that fun, and Trek’s range claims strike me as a bit ambitious (which isn’t surprising). Granted, range claims are always more than a little fuzzy, and the mountainous terrain of my local stomping grounds certainly has a lot to do with that. One ride in particular covered just 38 km (23.5 miles), but almost 800 m (2,600 ft) of elevation gain – all at maximum power assist (have I mentioned how much fun this bike is?). But when I got back home, the battery capacity was down to a middling 27%. Granted, I could have done that same ride on a lower power setting, but where’s the joy in that?

Since the IsoSpeed design is handling the lion’s share of compliance duties out back, the seatstays can be made a little bigger and stiffer to provide a more precise feel.

Here’s where that lightweight vs. full-power thing comes in again. While lightweight models like this Domane+ indeed feel more like non-powered bikes most of the time, there’s no substitute for watt-hours. To put that into perspective, I played around with a Canyon Grail:On gravel e-bike a couple of years ago, which is equipped with a full-power Bosch system and a much bigger battery. One ride I did on that bike covered more than 47 km (29.5 miles) with just shy of 1,200 m (3850 ft) of elevation gain – and there was enough juice left at the end that I almost could have done that ride twice. 

Granted, that bike was more of a bruiser than this Domane+, which does really feel a lot like a good, non-powered road bike in many respects. While it’s fun to blast around in full-power mode, kicking things down a notch or so dramatically extends battery life. There’s some noticeable friction in the TQ motor when pedaling without power at all – more from the bearing seals than parasitic mechanical losses, from what I can tell – but it’s not bad at all, and it certainly pales in comparison to what the motor is putting out.

Aside for the extra weight, the Domane+ genuinely feels pretty normal – certainly enough so that you don’t feel like you have to be in full-power mode all the time. And just as promised, the TQ HPR-50 motor is remarkably quiet so you’re not always audibly reminded what you’re riding, either. There is a whir that grows proportionally louder with pedaling cadence, but even at its loudest, you can barely make it out from the hum of your tires. At higher speeds, it’s drowned out entirely by wind noise. It’s easy to forget about it.

About that speed cutoff

As I mentioned earlier, your experience on an e-road bike will vary greatly depending on where you’re riding it (or perhaps more specifically, where you’ve purchased it). Although I found the Domane+ to be incredibly entertaining, it would have been very different had the motor cut out at 25 km/h as it would in Europe. There, the Domane+ would still be a blast when climbing, or perhaps more as a dedicated light-duty gravel rig with those 40 mm-wide tires. However, I’m not sure how much fun it’d be otherwise (and I know CyclingTips senior tech editor Dave Rome agrees on this one).

Kudos to Trek and TQ for so thoroughly engineering the motor assist cutoff when you do bump up against that mandated speed limit. Unlike many other e-bikes I’ve ridden, the power drops off gently and seamlessly, rather than feeling so abrupt that you wonder if a wire has suddenly come loose. 

But even then, the 25 km/h cutoff that much of the world would see on this thing also severely cuts into its utility. It’s virtually guaranteed that someone riding a Domane+ wouldn’t be able to enjoy a bunch ride with friends since they’d essentially be dragging an ineffective anchor all the time, and even more gradual climbs would likely be frustrating as the motor continually cuts in and out. It’d still be a boon for longer climbs if you’re ok with taking it a bit slower, and certainly on steeper ones. But aside from that, I’d urge anyone considering their first e-road bike purchase to seriously ponder the effects of that speed limit. 

What about the non-motorized bits?

Handling mostly feels like the regular Domane (and you can expect a review of the new non-powered Domane SLR from me shortly, too), although there are some caveats. I find it interesting that Trek equips the Domane+ models with such a broad spread in tire sizes, as it does affect the steering. I first tried my test bike with the stock 40 mm-wide Bontrager GR1 Team Issue gravel tires, and it was… ok. The steering felt heavy off-center, and the bike wasn’t nearly as eager to initiate turns as I would have expected. But when I switched to 35 mm-wide Schwalbe G-One RS tires, the handling instantly became much more natural, easily diving into turns and flowing through corners as it should. 

The Bontrager GR1 Team Issue tires on SRAM-equipped bikes don’t feel particularly fast-rolling, but that’s less of an issue when you’ve got 50 Nm of additional torque at your disposal.

Switching tires also highlighted another downside. Although the stock Bontrager gravel tires are quite grippy on hardpack and tarmac, they’re also surprisingly slow-rolling. With those Schwalbes installed, the bike felt much faster and alive (and I’m sure there’s a positive impact on battery range, too). 

Ride quality improved with the tire change, too, but it still couldn’t completely mask the imbalance between the front and rear ends. Trek’s IsoSpeed feature continues to work brilliantly, offering an incredibly smooth and compliant feel that (at least for me) never feels overly bouncing or intrusive. But even with the bigger Bontragers fitted, the front end is dramatically stiffer. Even medium-sized impacts jar your hands, and trying to attack washboard sections of packed dirt is absolutely brutal. My guess is the massively oversized down tube has a lot to do with this, which is something I’ve noticed on other e-bikes with similar proportions. 

There are some other quirks, too.

One of the TQ display screens is supposed to separately show your output and that of the motor. The motor figure seems believable enough, but the display of your output seems dramatically low. Granted, I didn’t verify this with a separate power meter, but I know what 200 W feels like, and when I see 150 W on the display, something seems off.

Naturally, the 2023 Domane+ features the latest incarnation of Trek’s superb IsoSpeed rear suspension system.

Aside from the tires, I don’t have much to complain about regarding the spec. The 10-44T cassette and 42T chainring offer plenty of range, and shift quality is very good. The jumps between sprockets are still a little bigger than I’d prefer for group road rides, but it’s fine when out solo. And kudos to TQ for powering the rear derailleur directly by the main system battery. It’s clean and convenient, and one less battery to worry about (although that also means if the system is totally, completely dead, you now can’t shift, either). 

The Bontrager finishing kit is generally excellent. The snub-nosed Verse Pro saddle is comfy, the Aeolus RSL 37V wide-format carbon wheels are fantastic, and kudos to whoever at Trek specified this wonderfully grippy and squishy bar tape. But the handlebar underneath that tape? I’m sure someone likes it, but it’s definitely not my cup of tea. The short reach and deep drop are an odd combo, and I was never able to find a remotely comfortable position for my hands in the drops. Thankfully, Trek’s solution for concealed cabling allows you to use any bar with a 31.8 mm clamp diameter.

Super fun, but keep the limitations in mind

Trek’s move to the TQ motor platform is interesting, if for no other reason than its longstanding relationships with other (and much better established) motor suppliers. However, the company clearly sees advantages in what the TQ HPR-50 provides, and after riding it myself, it’s hard to argue with Trek’s decision: it looks better, it’s quieter, and while TQ’s long-term reliability still needs to be proven, the simpler mechanical layout at least bodes well since there’s less to go wrong in there.

As promised, the Domane+ does feel a lot like a regular road bike in a lot of ways, and it’s undeniably fun to ride. But as I mentioned earlier, the experience will vary greatly with where you’re riding it. Although I found the bike incredibly entertaining, it would have been very different had the motor cut out at 25 km/h as it would in Europe. There, the Domane+ would still be a blast when climbing, but I’m not sure how much fun it’d be otherwise.

Either way, those looking for the more visceral thrills of a full-powered e-road bike won’t be blown away by the TQ motor’s modest specifications, but if you’re after more of a traditional feel with a little bit of a boost – and live in the right country – this seems like a bike well worth considering. 

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