This FSA plug has 4 separate pieces that can conform to the oval shape a little better. Can't say for sure the it has a small enough outside diameter to fit inside but there the grinding option. Contact TREK to find out if the plug needs to provide strength against crushing from the stem clamp first as this may not work. https://www.jensonusa.com/FSA-Compre...SABEgJbRPD_BwE or https://www.performancebike.com/prob...iABEgKdSfD_BwE