Standard-issue on the top-end Trek Domane road bikes, the Bontrager Race X Lite IsoZone bars are built to tame rough roads. But, this is no cruiser bar, no-sir-ee, this is a pure race bar with a soft side in just the right places.

Bontrager Race X Lite IsoZone Features:

  • IsoZone pads displace vibration by 20% neutralizing vibration and reducing hand numbness
  • Lighter and more compact than adding layers of tape or aftermarket pads
  • Includes two upper and two drop pads
  • Odor free closed-cell pads won’t absorb water
  • Includes one front and one rear cable groove for optimized bar wrapping
  • Lightweight OCLV carbon construction
  • VR-CF profile maintains compact VR-C shape with ergonomic flare at ends
  • Includes guide lines for alignment of stem and brake levers
  • Replacement pads available, Clip-On Compatible
  • Weight: 225 grams (42cm – as tested)
  • Reach: 85mm
  • Drop: 125mm
  • MSRP: $299

The Race X Lite IsoZone’s tamed the rough ride of the Scott Foil.

Bontrager Race X Lite Isozone Carbon Bars Review

When it comes to road bike components, Bontrager is one of the most respected names in the business. Synonymous with Trek, Bontrager can certainly stand alone as one of the most respected component manufacturers on the market for both road and mountain bikes. Their new Race X Lite IsoZone bars are built stiff for high-output racing, but also feature strategically-placed IsoZone pads to improve comfort for the long haul.

Installation of these bars is a breeze. The clear markings for brake lever placement as well as center lines for stems are more extensive than you’ll find with other brands. Built-in cable guides keep a flush look when wrapped. When placing the IsoZone pads, I was a bit leery that once I placed them down they would never come back up. While you certainly don’t want to mess it up too much, minor adjustments are easy and didn’t damage the pads or the adhesive. I installed these bars on my Scott Foil 40 test bike.

Depending on the layup of the carbon fiber, it can be stiffer and stronger than alloys or it can be softer and more compliant. In this case, the OCLV Carbon is laid out to give this bar UCI-level stiffness. Just to clarify, stiff doesn’t immediately mean they won’t absorb road vibrations, it just means that these are going to give you the ultimate in steering precision and err on the side of road feel.

As I mentioned, the IsoZone gel pads are strategically located on the bars for maximum comfort. Their research has shown a 20% increase in vibration dampening and I could certainly feel that difference. The tops are only slightly ovalized, but with the pads, I didn’t long for flat tops. As I pushed myself on long climbs, I was able to find just the right home for my hands where the IsoZone could do its magic. It’s truly amazing stuff and worked in perfect harmony with the Bontrager RL Fusion Gloves to give me the most responsive handling and comfortable ride possible.

The drops measure 125mm with a reach of 85mm. Bontrager calls this their compact VR-C shape and feature slightly flared ends.  The drops don’t have a fully-ergo bend in them, but the IsoZone material sort of acts as though they do and works in concert with the modified curve in the drops (a.k.a. Variable Radius). When descending in the drops or accelerating, these bars don’t flex one iota.  They simply respond in spades while the IsoZone significantly reduces fatigue and discomfort. Large bumps are softened and then the IsoZone pads take over the rest.

At $299, these are on par with the more expensive carbon bars on the market, but are certainly worth the price. As a strong recreational rider, I could go for just a tad more compliance in addition to the IsoZone. However, this entire package is hard to beat.

Learn more about IsoZone testing and performance: Bontrager IsoZone Presentation (PDF)

Good Race X Lite Isozone

  • IsoZone pads dramatically increase comfort
  • Bars remain stiff and responsive under hard efforts
  • Small chatter is naturally reduced, but liveliness remains for excellent road feel
  • Cable channels provide easy setup and a more fluid wrapping surface
  • Still ultralight — even with IsoZone pads

Bad Race X Lite Isozone

  • Aside from the IsoZone pads, these bars are extremely stiff — some may want more compliance
  • I’d prefer a little more ergonomic drop

Bottom Line: Bontrager Race X Lite IsoZone Bars

Road chatter has met its match with the race-worthy Race X Lite IsoZone bars. Trek’s OCLV carbon fiber is laid up to give you the most responsive bars on the market with excellent vibration dampening qualities.

Buy Now: Visit

About Author

A native of the Pacific Northwest, Jason quickly developed a love for the outdoors and a thing for mountains. That infatuation continues as he founded this site in 1999 -- sharing his love of road biking, mountain biking, trail running and skiing. That passion is channeled into every article or gear review he writes. Utah's Wasatch Mountains are his playground.


  1. Hey Jason,

    I recently test rode one of the Trek Domane bikes, and you are dead on about these bars! Loved the vibration dampening of them. The bikes IsoSpeed feature between the top tube and seat tube was also very effective.

  2. Pingback: Bikes Built for Cobbles… and You -

  3. Jason,

    I am looking to order a 2014 Domane 6 series via Project One in the coming week and I am trying to decide about some components, namely the Bontrager handlebars, stem and wheels. Since you have reviewed all three in the past year, I thought I would ask your opinion. Couple of my friends have said that Bontrager-branded items won’t hold their value as well, so i should get the lowest end and then get after market parts that do hold value better (Zipp, Easton, etc).

    I test rode a 6.2 with the Race Lite IsoZone (alloy) handlebar and it was okay. I would like to go carbon, not for weight, but for comfort. I ride 95%+ on the hoods and tops, and have hand and wrist issues on long rides. The Easton EC90 that you reviewed looked like it may be better for me than the X lite. The upgrade cost for me would be $157 for the X lite bar over the alloy bar (still has IsoZone pads, but Alum).

    For the stem, I wasn’t really going to go carbon, but you seem to really like the XXX lite. For me the price diff would be $110 to up to the XXX lite.

    Lastly, on the wheels. I can go lower end with the Race TLR or upgrade to the Race X lite TLR (not looking for carbon wheels right now). Not sure if the upgrade cost of $390 is worth it or if I should just go after market for the wheels. Not sure if I would go tubeless even with the TLR hoops. Thanks for pointers.

    • I wouldn’t let your friends sway you from good stuff — regardless of resale value. I’ve been impressed with the Bontrager components I’ve tested and would certainly recommend them. That said, the Bontrager RXL bars and XXX stem is a killer combination, but doesn’t give you much in the way of rise options. But with the slightly taller head tube on the Domane, that might be desired.

      I really like the Zipp Contour SL bars overall as a great balance between light weight, performance and comfort with the flat tops. The Easton EC90 SLX is way comfortable, but a bit noodly on sprints. The more I’ve ridden stiff, performance bars, the less I like the Easton. But, if comfort is what you’re going for, that one is a great option.

      As far as the wheels go, the RXL TLR wheels are fantastic! I’ve run them tubeless with R3 tires all season and (gasp!) have hung up my carbon hoops — they are that good! Granted, I’m going to bring back out the carbon hoops again for summer, but for the winter, I’m sticking with the RXL TLR’s. They are light and tubeless is so comfortable with amazing handling.

      • Thanks for the response Jason. I think I am convinced about the stem and RXL wheels, just not sure about the bar. I do very little sprinting and comfort will be important (going do do some doubles this year). The Bontrager bar seemed less ideal for my needs than the Easton based on your review.

        For the RXL wheels running tubeless, if there is a serious issue on a ride, you can put a tube in them, right? Not sure if I should order the Project One with the TRL tires (it’s an option) or wait and get the TLR upgrade kit later.

        • Yes, you can tube-em if necessary, but you do have to deal with the mess of the sealant. Mine have been rock solid for nearly 1000 miles and I’ve heard much of the same from others running these wheels. I share your concerns though.

          The Easton bars would be really good if you’re not sprinting. They were my bars of choice on all my century rides — including the Colorado Triple Bypass — last year.

  4. I am selling a brand new one of these off my new 2014 Trek Madone S7 Project One. It’s brand new and I am including Lizard Skin white DSP bar tape($36). The retail on this is $299 – I will take $150 and cover USPS Priority Mail shipping from Boston to you. Email me for pics or to purchase! Retail is $299 and the bar tape was $36. Awesome bars but I upgraded to Zipp S Aero.



  5. The bar says, ” 31.8mm dia/42cm wide/full OCLV Carbon ISO ZONE 125mm Drop 85mm Reach VR-C

    The look very sharp- smooth clean lines and glossy black. Very nice.

    My cell is six17.FIVE95.644eight if you want to shoot me a call/text.

    This posted June 2nd, 2014- in case anyone sees this a year down the road. I need to know if I’m selling or keeping these in the next 2 days-my new group set is on it’s way so I need to figure this out. My buddy is telling me $150 is an awesome deal for these bars+Lizard Skin DSP tape.

    • That’s the same width I have. If they were 44’s, I’d likely want them. I’ll leave your comments up on the site for a few weeks to give you a chance to sell them. They are excellent bars and I have them on my Devinci Leo SL right now.

  6. Francis Chapman on

    I haven’t seen a Trek Domane bike yet, but by their looks, they can surely make it to the toughest roads. Although I really want to get one, as of now, I’d just be contented with my Morpheus bike.

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