Here are my proposals for the first three days. There are options for each day. I have included a short description of each route, together with a map, a webpage link and photos (where possible) of the campsites.
Day 1 Roscoff to Carhaix-Plouguer
Option 1 full bike path (82kms) (700m ascent)
After leaving the ferry we work our way around the bay and then pick up the paved bike route EV1 / V7. It follows small roads and La Rivere de Morlaix to the town of Morlaix, where join the Voie Verte Ancienne Voie Ferree Morlaix Carhaix, and we remain on this rural bike pathway for the rest of the day to Carhaix.
The Voie Verte Ancienne Voie Ferree Morlaix Carhaix is a dedicated bike path, created from an old 19th century railroad. It is traffic free, part paved and partly packed gravel.
Despite being a bike route there are some lumps and bumps but never to more than 230m above sea level. The most significant being a gradual rise of 200m which starts after 32km.
The last 3kms of the ride is through the town of Carhaix-Plouguer to our campsite overlooking the L’Hyere river.
Option 2 part bike path / part rural roads (76kms) (680m ascent) [Preferred Option]
Although the full bike path option from Morlaix is traffic free, that will be more challenging as the surface is packed gravel and the route is likely to be punctuated with gates. This, therefore is my preferred option. We leave the ferry we work our way around the bay and then pick up the paved bike route EV1. It follows small roads and La Rivere de Morlaix to the town of Morlaix. In Morlaix we leave the bike path and take the D769 which follows the Le Queffleuth river and a number of other smaller rivers all the way to Poullaouen. We stay on this road all the way to Carhaix-Plouguer. Our campsite is situated on the SW of the town overlooking the L’Hyere river.
Day 2 Carhaix-Plouguer to Rohan
Option 1 full bike path (112kms) (400m ascent)
A Long day, but flatter than yesterday. After 5km we re-join bike route EV1, then stay on the traffic free bike route alongside the Nantes – Brest canal all day. There are three hills at about 15, 55 & 90km, with a downhill finish into Rohan. The route does not rise to more than 210m above sea level. The campsite is next to the canal, making for an easy get away tomorrow morning.
Option 2 part bike path / part rural roads (100kms) (500m ascent)
This first option is 12kms shorter but we still follow the traffic free canal side route EV1 for 66kms before leaving it at Mûr-de-Bretagne and taking a more direct route on quiet roads (D767 and D2) through the small towns of Neulliac, Pontivy and Noyal-Pontivy. The reduced distance is achieved by avoiding some of the meanderings of the canal towpath.
Option 3 part bike path / part rural roads (87kms) (500m ascent) [Preferred Option]
This second option is shorter still (reduced by another 13kms and therefore a full 25kms shorter than the bike path only route). Again we follow the canal towpath route EV1 but leave it after 40kms. We then take the D31 and D764 to Silfiac and then the D764 to Pontivy followed by the D767 and D2 through the small towns of Neulliac, Pontivy and Noyal-Pontivy to arrive at Rohan. This is my preferred option; it gives us greater opportunities for refreshments as it passes through more villages. It still provides us with a traffic free start to the day and is no hillier than the other two options.
Day 3 Rohan to Rieux
Redon was my intended stopping point, but the campsite closes at the end of August. Fortunately I was able to find another campsite in Rieux just 5 or 6km further on. Today, if it is even possible, the route is flatter still, with the full bike path option being only 60m of total ascent (although 9kms longer than the preferred option).
Full bike path option (94kms) (60m ascent)
We start the morning by cycling for about 37kms along the EV1 bike path alongside the Nantes – Brest canal to Le Roc Saint Andre. Here we change onto the V3 which is an old rail-trail for about 7kms before re-joining the canal towpath route. This section of V3 may involve some packed gravel trail but is slightly shorter than staying on the canal route as it is a more direct route eliminates some meanderings. We then re-join the EV1 canal bike path all the way to Redon. In Redon we pick up the V42 bike path which follows La Vilaine river to Rieux.
Part bike path / part rural road option (85kms) (230m ascent) [Preferred Option] We start the morning by cycling for about 37kms along the EV1 bike path alongside the Nantes – Brest canal to Le Roc Saint Andre where we change onto the V3 old rail-trail to just outside Pleucadeuc. This portion of the ride may involve some packed gravel trail but it is only about 15kms long. We then leave the bike paths and take the D774 to Pleucadeuc and on to Rochefort-en-Terre. Here we change on to the D21 to Malansac and then onto the D775 to Rieux. The route is very gradually downhill for the first 40km after which come the only hills of any significance (one at 44kms the other at 52kms). It is gently downhill for the last 4kms into town. The campsite is in the grounds of Le Parc du Chateau, overlooking La Vilaine river. This is the preferred option because of the additional opportunities it gives us to get refreshments and to see rural life.