You're most unlikely to need longs in summer in Germany. I've toured there for the last few years in June/July/August. As BTFB says, it can be HOT and thundery. I use RonHills over cycle shorts rather than cycle longs but have never needed them. My basic clothing kit has evolved to
- Short-sleeved cycle shirt
- Long-sleeved cycle shirt
- Sleeveless cycle shirt (never needed)
- Shorts x 2
- Ron Hill trousers (never needed)
- Light rain/wind-proof top (Montane)
- Rainlegs
- Quick-drying travel shirt for evenings
- Light and quick drying Rohan long trousers for cool/formal evenings
- Loose (Peter Storm) shorts for warm evenings & urban cycling
- Light fleece for cool evenings
- SPD cycle shoes
- All-terrain sandals
I've never needed the Ron Hills but would still take them.
The multiple cycle shirts get used in whatever combination suits the temperature but I've not needed the long-sleeved shirt.
The minimal weight of the Ron Hills and long-sleeved shirt seem like good insurance against an unlikely cold snap.
I keep money & keys in the loose shorts, in the top of a saddlebag, so I can easily put them on and be fully equipped if I stop in a town to explore.
The Montane jacket & Rainlegs have kept me as sufficiently dry through some very heavy rain. In summer, over-trousers seem well ott.
For shoes, I used sandals for the whole trip last year. Warm water bouncing off roads was a strange but pleasant feeling. Wearing proper shoes I don't bother about wet feet. They've never got cold as long as my core was warm enough - and I have white finger/toe disease so am quite sensitive to cold feet!
Hope that helps. It's all very personal though. I did the C2C with Norwegian friends a few summers ago - me in a thin cycle shirt while they were wearing fleeces!
Pete
Pete