The Not Quite Gravel Bike: Trek Domane 4.3 Disc


I bought this bike as a backup for my primary bike, which is a Trek Domane 5.2. I viewed Domane 4.3 Disc as a winter bike, which means mostly rain here in Northern California. The disc brakes and ability to handle bigger tires appealed to me.

Of course, I can never leave well enough alone, so upgraded several key components. The wheels, in particular, seemed heavy and clunky, so I replaced those with a set of Bontrager Affinity Pro TLRs. While still primarily aluminum alloy, they roll much better than the original wheels, due to the DT Swiss hubs and overall lighter weight. The 4.3 Disc includes Shimano 105 components for the most part, except for the crank, which is a heavier Shimano RS505 OEM crank. So that came off when I found an exceptional sale on an Ultrega compact crank.


The disc brakes are a little different, as they’re TRP hybrid brakes, which are hydraulic brakes designed to work with mechanical shifters such as the Shimano 105 STI levers. They work well, but give up a little on weight relative to either mechanical discs or all-hydraulic setups. That may be why the 2016 edition now use a complete Shimano 505 hydraulic brake set.

Trek builds the rear break neatly into the rear chainstay, keeping it out of the way of fenders, should you want to use them.


The drive train consists of Shimano 105 5800-class components, including the 11-32 cassette, derailleurs, and chain. Unlike Trek’s pricier models, the Domane 4 series uses external cable routing, making life easier on home mechanics. I also upgraded the handlebars to a set of Bontrager IsoZone Race Lite, which my dealer threw in for free. The gel padding on the bars makes life easier on my left shoulder, which seems to be getting older faster than the rest of me.

One of the goals of the bike included riding on fatter tires to ease the ride over bumpy roads and gravel, so I rode on a set of Specialized Armadillo Elite 30mm tires. While incredibly durable, they also came with a relatively harsh ride. So those came off, to be replaced with 28mm Continental  4 Season rubber.

So did the bike meet my goals? As it turns out, not really. I found myself riding it less and less, even in the winter conditions for which I chose it. It took me some time to figure out why I avoided riding the 4.3. The problem lies with three little digits.


The Domane 4 series is built on Trek’s 400 series carbon. Trek suggests the 400 series offers nearly the stiffness of the 500 series and above, just a bit heavier and with a little more compliance. For whatever reason, the Domane 4.3 simply seemed unresponsive compared the the 5.2 I was used to riding. In fact, I’d go so far as to say my old steel-frame Jamis Quest rode and handled better. It’s sexy to say you own a bike with a carbon fiber frame, but it’s clear from my very different experiences with seemingly similar bikes that not all carbon frames are created equal.


    • doug on April 27, 2018 at 10:28 pm
    • Reply

    I’m thinking about getting a 4.3, which I can get new for a good price and mostly because I like the paint scheme better than newer models. What you say about the different feel in frames is instructive though, so maybe it would be better to go with a 2018 SL5 gravel, for example. I’m also concerned about the porky weight of the 4.3, which I think is 21.5 lbs stock or so. Did you happen to weigh it after you changed out wheels and other components?

    1. I owned a Domane 4.2 for awhile (2015 model). The overall feel of the ride seemed somewhat clunkier. Of course, it could partly have been other components contributing, but the series 5 frames seem noticeably more responsive.

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