Lightest-ever disc-brake Trek Domane loses front IsoSpeed to go faster

The new Trek Domane is claimed to be lighter and faster after losing front IsoSpeed and gaining an integrated stem.

The brand says it has shaved “a dramatic amount of weight” from the old Trek Domane, with both the entry-level SL and pricier SLR said to be 300g lighter.

Trek says this makes the fourth-generation Domane the lightest disc-brake version of the bike.

The company claims this adds a “performance tilt” to the bike often chosen for the cobbles of Paris-Roubaix.

The new models have more integration at the front and rear of the bike – the stem is integrated, while the seatpost clamp is now hidden in the top tube.

Trek has added top tube bag mounts to the Domane SL and SLR frames, and kept the geometry’s endurance slant.

The bikes come with 32mm-wide tyres – apart from the top-of-the-range Domane SLR 9 eTap – and have clearance for tyres up to 38mm measured width, according to the brand.

The new “race-focused” Trek Domane RSL, which was made for the brand’s WorldTour teams, is now available only as a frameset.

Trek says tube shapes are similar to the Domane SL and SLR, but the RSL frameset has the same H1.5 geometry as the Trek Madone.

New IsoSpeed

IsoSpeed stays at the back of the bike, but you can't adjust the compliance. - Russell Burton / Our Media

IsoSpeed is Trek’s built-in suspension system that allows the bike frame to flex, it says, to boost comfort.

We first saw top tube IsoSpeed on the Trek Madone before it disappeared in favour of a seat tube hole on the new Trek Madone SLR, called IsoFlow.

The new Trek Domane still features rear IsoSpeed, now positioned at the top tube and seatpost junction, but it is no longer adjustable.

Front IsoSpeed has gone from the front of the headset.

The Domane SL used to have IsoSpeed in the seat tube, but Trek thought this disadvantaged smaller riders.

Trek’s director of road bikes, Jordan Roessingh, says: “Seat tube IsoSpeed gets more rigid as the frame gets smaller.”

Roessingh explains that top tube IsoSpeed makes compliance consistent on all frame sizes.

On the new Domane SLR, Trek says the level of compliance is fixed at the equivalent of the most comfortable setting on the old bike.

Explaining the removal of adjustability, it claims riders tend not to alter the degree of suspension and the simplified system saves weight.

Same Domane character

The Domane SL and SLR have down tube storage, but the RSL does not. - Russell Burton / Our Media

As is increasingly common on the best endurance road bikes, there are new top tube bag mounts, along with the existing down tube storage on the Domane.

Trek emphasises the Domane’s versatility, saying the “comfortable, performance road bike” can handle everything from Paris-Roubaix cobbles to long weekend rides, light gravel and fast group rides.

Roessingh stresses the Trek Checkpoint is the brand’s “gravel-first bike”.

Tyre clearance for both Domane SL and SLR models remains 38mm measured width, large enough for narrower versions of the best gravel tyres.

This drops to 35mm with full-length mudguards fitted (the bikes have hidden mudguard mounts).

By contrast, Trek says the Domane RSL “prioritises ultimate speed and performance over comfort and versatility”.

It has clearance for 35mm tyres and no mudguard mounts or down tube storage, saving 100g on the SLR frame.

All of the new Domanes come with tyres and wheels set up tubeless, Trek says.

Aero changes

Trek claims to have made the seatpost and tubes less draggy. - Russell Burton / Our Media

The Trek Domane SL and SLR have the same-shaped frame, the difference being the SLR’s lighter 800 Series OCLV Carbon.

Trek has ditched the old, round Domane seatpost for a D-shaped Kammtail Virtual Foil seatpost.

The new seatpost comes in two lengths of 280mm and 320mm, with two offset options per length: 5mm and 20mm.

Trek promises its new stem is easy to adjust. - Russell Burton / Our Media

The new integrated RCS Pro stem has fully internal cable routing, which Trek claims “cleans up aesthetics” and reduces drag.

According to Trek, the RCS Pro enables riders to swap stem sizes without removing brake hoses or shift housing. Stems with -7 or +7 degree rise are available.

Lightest and fastest

The new Domane is said to be sportier and as versatile as the previous generation. - Russell Burton / Our Media

The new Domane SL is said to weigh 700g less than the first generation.

Besides frame changes, Trek says the reduction comes from lighter components and tubeless wheels and tyres.

The Domane is also more aerodynamic, and therefore faster, due to further use of Kammtail tube shaping, according to Trek.

Trek has not provided data to back up this claim.

2023 Trek Domane SL and SLR geometry

The head tube on the SL and SLR is 5cm taller than the RSL. - Russell Burton / Our Media

The Trek Domane SL and SLR have what Trek calls its H2 geometry, typical of endurance road bikes. This consists of a higher top tube, longer wheelbase and shorter reach than Trek's race bikes.

Frame size	44	47	50	52	54	56	58	60	62
Seat tube (cm)	39	42	45	47.5	50	52.5	54.8	56.7	58.6
Seat tube angle (degrees)	74.6	74.6	74.6	74.2	73.7	73.3	73	72.8	72.5
Head tube length (cm)	9.5	11	13	14.5	16	17.5	19.5	22	24.5
Head angle (degrees)	70.3	71	71	71.3	71.3	71.9	72	72.1	72.1
Effective top tube(cm)	50.1	50.9	51.9	53	54.2	55.4	56.7	57.9	59.3
Bottom bracket drop (cm)	8	8	8	8	8	7.8	7.8	7.5	7.5
Chainstay length (cm)	42	42	42	42	42	42	42.5	42.5	42.5
Offset (cm)	5.3	5.3	5.3	5.3	5.3	4.8	4.8	4.8	4.8
Trail (cm)	6.6	6.1	5	5.9	5.9	6.1	6	5.9	5.9
Wheelbase (cm)	98.3	98.6	99. 6	100.3	101	100.8	102.2	103.2	104.2
Standover (cm)	65.7	68.6	71.6	73.5	75.4	77.6	79.6	81.7	83.5
Reach (cm)	36	36.4	36.8	37.1	37.4	37.7	38	38.3	38.6
Stack (cm)	51	52.7	54.6	56.1	57.5	59.1	61.1	63.2	65.6
Stem length (cm)	60	70	80	90	90	100	100	110	110
Saddle rail height min (w/short mast, cm)	53.5	55.5	58.5	61.5	64	67	69	71	73
Saddle rail height max (w/short mast, cm)	60	62	65	68	70.5	73.5	75.5	77.5	79.5
Saddle rail height min (w/tall mast, cm)	56.5	58.5	61.5	64.5	67	70	72	74	76
Saddle rail height max (w/tall mast, cm)	63	65	58	71	73.5	76.5	78.5	80.5	82.5

2023 Trek Domane RSL geometry

The Trek Domane RSL uses the brand’s more aggressive H1.5 geometry, as seen on the Emonda and Madone.

It is 4cm lower at the front end than the Domane SL and SLR, according to the brand.

The H1.5 dimensions are part way between the long and low H1 pro-level fit, which is now consigned to the history books, and the more upright H2 endurance setup.

Frame size (cm)	52	54	56	58	60
Seat tube (cm)	48.3	50.1	52.5	55.3	57.3
Seat tube angle (degrees)	74.2	73.7	73.3	73.3	72.8
Head tube length (cm)	9.5	10.4	12.9	14.8	17.1
Head angle (cm)	72.6	72.6	72.82	72.8	72.8
Effective top tube (cm)	53.4	54.4	56	57.3	58.5
Bottom bracket drop (cm)	8	8	7.8	7.8	7.5
Chainstay length (cm)	42	42	42	42.5	42.5
Offset (cm)	5.3	5.3	5.3	5.3	5.3
Trail (cm)	5.2	5.2	5.1	5.1	5.1
Wheelbase (cm)	99.3	99.8	101	102.5	103.6
Standover (cm	72.7	74	76.4	78.7	80.7
Reach (cm)	38.8	39	39.5	40	40.4
Stack (cm)	51.8	52.7	54.8	56.7	58.6

2023 Trek Domane SL, SLR and RSL build specs, pricing and availability

SRAM Force is on the Domane SLR 7. - Russell Burton / Our Media

The 2023 Trek Domane SL, SLR and RSL are available to pre-order now in 12 different builds (with five colourway options for each build).

The frames can be used with Shimano mechanical and electronic groupsets apart from the electronic-only RSL frameset.

SRAM electronic, but not mechanical, groupsets are compatible because the new Domane frame doesn’t have a front derailleur housing stop.

Trek has not specced any new Domanes with Campagnolo groupsets due to lack of availability, the brand says.

Frame sizes range from 44cm up to 62cm for the Domane SL and SLR and 52cm to 60cm for the RSL frameset.

The whole 2023 Domane range has a T47 threaded bottom bracket.

Prices for complete bikes start at £3,350 / €3,499 / $3,499.99 / AU$4,499.99 for the Domane SL 5 and rise to £12,500 / €13,999 / $13,199.99 / AU$17,499.99 for the Domane SLR 9 eTap.

Three framesets can be purchased separately.

The Domane SL Disc costs £2,700 / €2,999 / $2,499.99 and the price of the Domane SLR Disc and Domane RSL Disc is £4,500 / €4,999 / $4,199.99. Australian pricing is unavailable.

The Domane RSL and Domane SL framesets have claimed weights of 1.6kg and 2.6kg respectively.

Trek has not released the weights of the Domane SLR Disc frameset or Domane SLR 6 bike.