The Aire Valley Towpath

This ride from Leeds follows the River Aire Valley on the towpath of the Leeds and Liverpool Canal.  The canal itself is 128 miles long being the longest canal in the UK, although the two cities are only 64 miles apart as the crow flies.

Throughout it's length the path is well surfaced and as you would expect on a canal path, there are minor gradients only where there are locks. The rise over 12 miles was a mere 33 ft.
Conveniently the path starts very close to Leeds Railway Station at Granary Wharf.  Here there are several eateries where you can stock up with food and drink for the journey, although there are several cafes and pubs along the route.
Travel from Derby by train is via Sheffield and best done with a Derbyshire Wayfarer Ticket and single tickets from Sheffield to Leeds.  For Seniors (ie over 60) the cost is £6.70 and the Sheffield to Leeds ticket costs as little as £2.95 each way, so a total of only £12.60.  The downside is that the Sheffield to Leeds train takes an hour and 15 minutes, stopping at every intermediate local station.
As with most canal rides you cannot get lost so no need for maps or more sophisticated means of navigation.
The canal-side scenery is superb with views of the surrounding countryside and lots of interesting infrastructure, with both old and new buildings.  The only thing that spoils it is the appalling graffiti sprayed by the local morons on the beautiful stone walls and even on the lock gates and the bridges.

At Sheffield station we await a train crew for the Northern Trains service to Leeds.

 Accommodation for cycles on Northern Trains is excellent, although the seating for humans is rather spartan.

Here in Leeds the canal appears to flow beneath the railway station so not difficult to find in the dark tunnels.

Some impressive modern buildings surround the station and the canal basin.

Here is Granary Wharf at the start of the ride, with plenty of places to buy food and drink.

Straight ahead here, guided by helpful police.

Straight on here onto the towpath.

The start of the towpath is here.

More high rise apartments overlook the canal and the City of Leeds.

A strange sight on the opposite bank of the canal.  Not sure what it is but you don't see many of these anywhere.

The Abbey Inn - not recommended

A few miles on is The Tiny Tearoom (recommended). Obviously a popular stopping place for cyclists, being right next to the towpath.

And the path ahead.

Several railway bridges cross the canal.

From here on just follow the towpath and enjoy the scenery once you are clear of the appalling graffiti on the walls.  This is not a feature as you
get out of Leeds and into the countryside.

Verdict
A superb scenic ride with good surfaces apart from a few short stretches.  Minor gradients only, such as this (above) on approaches to the locks.  Return along the same route back to Leeds Railway Station.
Regarding the mileage for this there-and-back ride there is no limit of course.  I cycled about 13 miles out, making a total of 26 but would hope to cycle further on my next visit.
Take a camera for some great photographic opportunities to record memories of a wonderful day out.
Expect path to be busy at weekends, holidays etc. so best ridden midweek if you can.