Indeed it appears online that the Lesovo border is for commercial trucks only, and I can see where you get that view.
This blog, for example, notes that the road they are on to the crossing at Malko Tarnavo is almost devoid of traffic, as all the trucks go through the Lesovo border.
The Lesovo border was the focus on the news recently when it looked like it might even get blockaded in strikes, but appears to be open. However, the photos on the news indicate that even there - it's just trucks coming through.
Finally, the Wikipedia article Hamzabeyli, Lalapaşa notes, along with a photo:
A view of the Hamzabeyli border crossing point with its counterpart
Lesovo (Note the exclusive truck traffic)
However, it's also in the news that in 2005, a new border was opened at this crossing, and is the first to be opened in the country for the last 16 years. It says nothing about commercial exclusivity.
Lonely Planet also confirms that there are several borders into Turkey for travellers, and specifically mentions this crossing.
So really, what we want is EVIDENCE of a cyclist traveller crossing into Turkey at this border point. And so we go to a messageboard on triumphtorque:
Crossed the border into Turkey at midday at Hamzabeyli (new crossing
North of Edirne) Got my visa and documents checked (about 6 times at 6
different windows, each one where i had to stop, then restart by
taking saddle off...) and was on my way in less than 30 mins.
So there's a motorcyclist in 2009 crossing with no problems at all.
Then we go to this page on an International Bicycle Tour (the site is actually down for me, but I used google cache to access):
Turkish, Bulgarian and Greek high school students will get together
and ride their bikes. Greek students will enter Turkey from Pazarkule
Boarder Gate and Bulgarian students will enter from Hamzabeyli Boarder
Gate. All students will meet at the city center and will ride their
bikes to Yildirim Beyazit Saglik Museum (Health Museum) then they will
go to the Campus of Trakya University and will attend University’s
So there's a bunch of high school students from Bulgaria entering from the border at Hamzabeyli.
Hope that helps!