From sea level at Kinlochleven and West Highland Way 7: Kings House to Kinlochleven
, the trail climbs very steeply (700 ft in one mile). There are several sections, a couple hundred feet long, armored with very large rocks and multiple step ups. Most riders will probably find themselves walking part of the way up. The climb is through one of the rare forested sections of the northern half of the WHW though, so you might count on some shelter from the elements.
Finally, you'll pop out of the trees onto the old military road. This section is quite rocky (babyhead and/or gravel most of the way) and a little bit rougher than some of the military roads in previous segments of the WHW. The military road climbs gently for two miles to just over 1,000 ft before beginning the long descent into Fort William back at sea level. The military road follows two valleys that wrap south and west around the Mamore Mountains.
At around the seven mile mark, the WHW leaves the military road onto a singletrack to the right. The singletrack passes through farmland and then onto Forestry Commission land. Some of the Forestry Commission land has been logged in 2017, so the trail is not quite as pristine as it used to be. This section is nevertheless enjoyable with some technical features (but not as difficult as those on the climb up from Kinlochleven).
The singletrack ends around the 10.7 mile mark on a gravel/dirt forest road that descends steeply through a forest into Glen Nevis. You'll have occasional glimpses of Ben Nevis (the highest point in Britain at 4,413 ft), but for a really great view, take the Dun Deardail
spur trail up to an old Iron Age Dun Deardail fort which has commanding views of the surrounds, including Ben Nevis.
The WHW takes an abrupt right at a four-way intersection around 13.3 miles which takes you to the Glen Nevis Road and the Glen Nevis Visitor Center / car park in case you want to make an ascent of Ben Nevis (presumably without the bike). From here, local roads take you to the terminus of the WHW on the High Street in Fort William.
In Fort William, you can connect to the East Highland Way (83 mi to Aviemore, another outdoor Mecca) or the Great Glen Way (73 mi to Inverness).