Wait:
the Tektro R538 (if is the same as the ones on my rain bike) does not fit the mericer front with 700c deep V's because they are long reach (Brake Reach: 47 - 57) where for my mercier, im using Shimano Sora (Brake Reach: 39 - 49 and its similiar to shimano tiagra.. and the rest just differentiated by weight and price)
because i think front has reach of about... 40-45...
do this instead:
Tektro R530 (grr.. out of stock but you know, you can use google)