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Trek Checkpoint SL 6 review

5 Aug 2022

Neat tricks combined with smart design equals good fun. The Checkpoint SL is the sweetspot in Trek's gravel range

Cyclist Rating: 
Effective geometry, sensible spec, neat extra frame features, comfortable
Heavy, non-removable front derailleur mount, headset cable integration design isn’t watertight

Trek has revised its popular Checkpoint gravel bike, introducing a new geometry that lets the bike be taken further off the beaten track.

The range has expanded too. The Checkpoint SL range sits in between the racy SLR range and the aluminium ALR bikes.

Cyclist contributor Ben Delaney found the Checkpoint SLR 9 to be all the bike a gravel racer could need, provided their pockets are deep enough, but I’d argue the Checkpoint SL range is the best overall proposition for most gravel riders.

The Checkpoint SL 6 on test is capable of fast, aggressive riding but also has the versatility to be used for adventurous riding on technical terrain.

Its geometry overhaul, combined with high-quality component selection, makes it great to ride on nearly all terrain, and its IsoSpeed decoupler system delivers impressive seated comfort.

Trek Checkpoint SL 6 development

The gravel bike market is continuing to develop at a fast pace and what was seen as forward-thinking design perhaps only just a couple of years ago now seems unfeasibly conservative.

Trek’s first-generation Checkpoint was regarded as a progressive gravel bike when it first came out in 2018 (it had an adjustable rear axle and everything), yet things have shifted to such an extent that its design would be considered barely more capable than a contemporary endurance/all-road bike nowadays.

The new Checkpoint was released to address that and it does so emphatically – pushing aspects of its design like geometry more resolutely into off-road bike territory, while at the same time introducing more utility and choice to the range in general.

The new Checkpoint comes in 3 guises and each tries to cater for a different rider and set of circumstances. At the top of the tree there is the SLR, which is a stripped back, aggressive version of the design aimed at racers.

There’s the ALR too, which swaps carbon composite for aluminium and gains features like a more relaxed fit and extra mounting points, for those in need of a rugged workhorse version of the design.

Then there’s the SL, which sits somewhere in the middle. It uses Trek’s mid-tier OCLV 500 carbon construction and offers the capability to match the much of the SLR’s raciness, but also the versatility of the ALR to go for long distance adventures off road. As such, it strikes me as the ideal middle ground to suit the vast majority of riders’ needs.

Trek Checkpoint SL 6 frameset

The Checkpoint SL’s frameset in undeniably slick. It borrows many style cues from the Trek’s latest Domane SLR and Émonda SLR road bikes, such as the distinctive head tube, and the profiled headset top cap that accepts the cables running down from an otherwise conventional cockpit.

It also makes use of the Isospeed decoupler mechanism that Trek employs on its other platforms too.

There are now several versions of Isospeed, but the Checkpoint SL uses the device’s original arrangement: aside from its origin at the bottom bracket junction the seat tube is essentially detached from the rest of the frame, connected to the seat tube cluster by an axle mounted on bearings.

This allows the seat post and seat tube to flex fore and aft independently of the rest of the frame, without compromising on stiffness.

There are some Checkpoint-specific features that helps set the bike apart from designs like the Domane and Émonda though.

There’s a neat down tube hatch hidden underneath the bottle cage mount, a bash-guard on the down tube, a dropped driveside chainstay that helps the bike comfortably clear 45mm 700c tyres, and there are mounting points aplenty, with several on the main triangle and down the fork blades too.

You wouldn’t perhaps notice straight away though, as everything seems very nicely integrated.

Trek Checkpoint SL 6 build

Aside from the SRAM Rival eTap AXS groupset, the Checkpoint SL6 build comprises exclusively parts from Trek’s component brand Bontrager.

There was once a stigma attached to in-house componentry however the parts that Bontrager produce are a prime example of why that is largely no longer an issue.

From what I can tell the build quality is beyond reproach and the performance attributes of a lot of Bontrager’s components rival that of many specialist brands.

By keeping things in-house Trek could even design kit to work specifically with the features of the Checkpoint frameset.

For example, the cockpit is made up of a Bontrager stem and bars that create a short reach to balance the lengthened reach of the frameset.

Both components are made from aluminium and simple in design, which I like – design simplicity is an indicator that something will be easy to live with and is fundamentally good quality.

The carbon Bontrager seatpost was again unfussy and seemed to pair well with the flexible, IsoSpeed-decoupled seat tube.

The Bontrager P3 Verse Comp saddle was perhaps the only low point for me on the spec list. While the shape is nothing to fall out with, it’s bulky and its padding was too squishy.

I’d prefer to use a saddle with less padding that is more supportive, but it's an easy component to swap out. I need to recognise that it’s also highly subjective part of the build, so your results may vary, and you could well find the saddle is a good fit for you.

The wheels, however, are an excellent choice between budget and performance. The Paradigm Comp 25 design is a little weighty, but it boasts a 25mm internal rim width that supports wider gravel tyres nicely.

I’ll add that Bontrager’s snap-in rim strips are a fantastic way to set up rims tubeless, being far quicker to install than traditional tape, though they can only be used on the Bontrager wheels they come with.

The Bontrager GR1 Team Issue 40mm tyres were a similarly excellent match for the wheels. They felt grippy in dry gravel conditions, but the low-profile tread still felt supple and speedy on the road. The tan sidewall colour looks very nice too.

SRAM’s Rival eTap AXS contributes to the bike’s 9.3kg overall weight however functionally it is superb.

In its 1× XPLR guise, the 40-tooth chainring worked nicely with the 10-44 cassette to give great range without too big a jump between each sprocket.

For the varied, predominantly off-road terrain the Checkpoint SL6 is aimed at covering it's a great set-up, even if the 1× chainring annoyingly highlights the fact Trek didn’t opt for a removable front derailleur mount. Then again that’s hardly the fault of the groupset.

Trek Checkpoint SL 6 geometry and sizing

Without doubt the Checkpoint’s most important feature is its new geometry. The frameset is longer at both ends: reach has grown by around 20mm, and chainstay length is up 10mm, but to keep the riding position normal shorter stems have been specced, with shorter-reach bars too.

Head tube angles have relaxed a bit, but more importantly fork rakes have dropped. Both changes combining to result in a significant increase in trail for a given tyre size.

For example, this Checkpoint SL6 with its 40mm Bontrager GR1 tyres has a trail figure of 67mm, which is pretty long.

Frame geometry is not often something that gets tweaked so significantly and it could be considered a bold move by Trek to change the recipe of the first-generation Checkpoint, given that it was considered to be such a well-rounded bike.

However, gravel bikes have only been getting more capable off-road so it is understandable that Trek has modified the bike in such a way, particularly when the result is so successful.

Riding the Trek Checkpoint SL 6

That longer wheelbase and slacker handling geometry has all been done with stability in mind, and the effect was noticeable in off-road conditions.

The long trail figure meant that the front of the bike was more inclined to understeer when nearing the limit of grip on loose ground, as opposed to simply washing out without warning, giving me more of a chance to correct things and remain upright.

Likewise, over rocks the Checkpoint’s front wheel ate big off-centre strikes that would cause other quicker-handling bikes to jerk off line. While the bike could never be described as any more than sedate on the road, the short 90mm stem and short-reach bars kept the handling from trending towards sluggishness.

The Checkpoint’s balance of geometry and componentry has been expertly judged by Trek in my opinion.

The Checkpoint’s long dimensions and 9.3kg weight meant it didn’t have the turn of speed that some gravel bikes do buts its oversize tube profiles meant it felt sturdy if not sprightly under acceleration.

In fact, I’d say it’s one of the bulkiest bikes in its category. The oversize headset bearings mean the head tube is broad and the natty storage compartment in the down tube means that is similarly girthy.

Trek’s sensible use of a T47 bottom bracket means the BB junction is large and even the seat stays are unusually substantial.

It's Trek’s use of the Isospeed decoupler mechanism that means it can build to such proportions with no penalty to ride quality.

It frees the seat tube and seat post up to flex along their entire combined length, so with such a long member through which to dissipate vibration and neutralise big bumps, the device is highly effective at improving comfort.

Trek Checkpoint SL 6 verdict

I have some niggles with a couple of finishing details – the headset port that accepts the hydraulic hoses into the frame isn’t watertight, and the front derailleur hanger, not being removable, is an eyesore – but broadly speaking Trek’s Checkpoint is a well-specced and highly capable machine to go gravel riding on.

Trek Checkpoint SL 6 spec

Price £4,000
Brand Trek
Frame Checkpoint SL
Fork Checkpoint SL
Weight 9.3kg (size 56)
Sizes available 49, 52, 54, 56, 58, 61
Levers SRAM Rival eTap AXS
Brakes SRAM Rival AXS
Rear derailleur SRAM Rival eTap AXS
Front derailleur N/A
Crankset SRAM Rival AXS 1×, 40t
Bottom bracket Sram DUB T47
Cassette SRAM XG-1251, 10-44
Chain SRAM Rival AXS
Wheels Bontrager Paradigm Comp 25
Tyres Bontrager GR1 Team Issue, 40mm
Bar Bontrager Elite Gravel, 42cm
Stem Bontrager Pro, 90mm
Seatpost Bontrager Carbon
Saddle Bontrager P3 Verse Comp

Pick of the Kit

Castelli Endurance 3 bib shorts

The Endurance 3 bib shorts are mid-level offering from Castelli that get the most important things right. Despite costing significantly less than Castelli’s top bib shorts they use the same Progetto X2 Air Seamless chamois, which is very comfortable.

The panel shaping of the body fabric is a little less finessed, meaning a few more seams than you’d find higher up the range, but I never found I noticed them during my rides.

I particularly like the Endurance 3’s Giro3 hem gripper design, which is a wide band comprising thin elastic strands that stay put, but don’t cut in.

Products reviewed by Cyclist are independently selected and tested by our editorial team. Cyclist may earn an affiliate commission if you make a purchase through a retailer link. Read our reviews policy.

    Trek Checkpoint SL 6 alternatives

    Trek Checkpoint SLR 9

    The £11,250 Checkpoint SLR 9 is a no-holds barred gravel race bike. It uses a higher-tier carbon layup than the SL – OCLV 700 versus 500 – and a revised Isospeed design to shed weight, and its spec list is universally excellent.

    Trek Checkpoint ALR 5

    Trek’s Checkpoint ALR 5 is its most accessible at £2,150. The frame is made from Trek’s 300 Series Alpha aluminium and it has the adjustable rear axle of the previous Checkpoint so users can alter its geometry or boost its maximum tyre size.

    Review photos: Lizzie Crabb, product photos: Trek Bikes