We chose the Shimano 105 group-set for the build and the GS medium-caged rear derailleur to cater for a big sprocket for some steeper, longer climbs like Mont St.Victoire in Provence and the Pyrenean Cols we ticked off last year.
However, my choice of chainset wasn't too clever. I went for a 165mm crank length which was fine but I worked out that a 38 tooth chainring was ideal for Youth gear restrictions and purchased a Stronglight 130BCD set up. This was perfect for racing but, even with a 32 sprocket, not great for any climbs over 8% for a 10 or 11 year old and I couldn't go smaller with 130BCD.
This year my son and I are planning to tick off some Tour climbs in the Alsace region of France. We decided to swap his front chainset to a compact and I coincidentally found a new SRAM APEX with 165mm cranks offered for sale at a reduced price. Buy it now.
The black coloured APEX goes well with the 105 groupset.
My son finds it much easier to spin up the climbs now and, whilst his racing is on hold, he can flick it up to the 50 tooth chainring and push a bigger gear. Our average speed around one of the local training rides has increased by 1mph to 14mph, so the change is good and we are looking forward to conquering the Grand Ballon.