Simpson and Walker will be part of an eight-rider Yorkshire MTB team at the British Cycling Inter Regional Mountain Bike Championships at Cathkin Braes, Scotland.
The team will be run on professional lines with a team manager as the British Cycling Yorkshire region team.
Selection was by merit and Richardsons Cycle Club rider Simpson (14) has had some excellent results in the Regional (North Of England) Mountain Bike series with third places at Dalby and Richmond.
Fifteen-year-old Walker has been having a superb year with race wins at Stockton Cycling festival and York Sport West Riding track league victories
Walker also enjoyed some more success at the TLI Youth National Championships staged at Middlesbrough Sports Village.
The TLI are a voluntary body supporting Age Related Cycling for All.
Walker (Acre RT) attacked the combined under-14 and under-16 race on the third lap of 35, riding solo for the remainder of the race Walker took the national title in style.
Otley Grand Prix is one of the Premier Town Centre races in Yorkshire, Bob Hewitt (YH Training Scarborough RC) took the opportunity to ride against the professional teams of Raleigh, Madison Genesis and JLT Conder in the Main race.
Hewitt was holding his again against a strong field including current national champion, Ian Bibby.
Unfortunately, the YHT rider punctured halfway through the race and had to withdraw, but this was a great experience for Hewitt proving there are big things ahead for the rider.
Walker rode in two of the support races.
First up in the under-16 Lads Race, Walker rode in the lead bunch for the whole race, he manoeuvred to the front of the bunch at the bell.
Attacking hard on the hill Walker moved clear, but unfortunately on the fast run-in he was swamped by the bunch and rolled home out of the placings.
Walker then rode alongside five of his teammates in the ¾ Cat Otley Classic.
Working under team orders, Walker again attacked hard at the bell with the aim of setting up a bunch sprint for his team captain Joe White. Walker was again swamped in the finish.