Part of the Chiltern Rivers Series
River start: Off Lilley Bottom Road, north-west of Whitwell, Hertfordshire
River end: Confluence with River Lea, north-east of Hertford Town Football Club, Hertford, Hertfordshire
River length: 20 km (12 miles)
Cycle route start / end: Circular from Hertford Town Centre
Cycle route length: 53 km (~33 miles)
Cycle route elevation change: +/- 372m
GPX File: get via Buy Me a Coffee
Other routes touched (walk): Lea Valley Walk, Cole Green Way, Hertfordshire Chain Walk, Hertfordshire Way, The Chiltern Way Northern Extension,
Other routes touched (cycle): NCN Route 12 and 61, Chilterns Cycleway
Maps:
- OS Explorer Map (182) St. Albans and Hatfield, OS Explorer Map (193) Luton
- Stevenage, OS Explorer Map (194) Hertford and Bishop's Stortford
Links: River Mimram, Whitwell, Welwyn, Hertford

This was to be the final trip in my Chilterns Rivers project, and one to satisfy my completist nature. That idea changed during research for this blog post as I noticed that I’d missed the Ouzel, the Flit and the Hiz. Not a big deal as it gives me more trips to do this year.

I’d already attempted this trip earlier in the year, only making it 5 miles in before abandoning it. I’d just come back from my Balkans trip and I was in the mood for another adventure. The wife was out for the day and tackling the Mimram seemed like a great way to spend a Sunday. It wasn’t. What I’d not factored in was that I was exhausted from the Balkans trek and it was also the middle of a heatwave. I’d also driven an hour to Hertford before realising that I’d not packed my backup USB power charger and my phone was already down to 50%. This is a complicated route and I wasn’t going to crack it without the GPS route. For some unknown reason I set off anyway then decided 5 miles in that I had neither the power in my phone or my body to complete it. My second attempt was better planned. January 2nd wasn’t in a heatwave, I was fully rested after Christmas and I’d brought my charger. I’d also brought my friend Charlie for added entertainment.

Hertford is a great base for the trip as it's a nice town with lots of parking and choices for food. For the circular trip we took an North-Westerly anti-clockwise route along mostly quiet county roads to find the source. The actual source is not accessible but we picked a quaint pond nearby to mark the start of the river section. From here the route heads South-East also along quiet country roads back to Hertford. The first couple of miles follows Lilley Bottom Road through Whitwell High Street, crossing over the river several times.

By the time we got to Welwyn we were ready for a coffee break. Despite having several pleasant looking pubs nothing seemed to be open so we continued on. This final section was the most interesting as it gave us a chance to get off-road as we got onto some bridleways through Panshanger park. Shortly after Panshanger we joined the Cole Green Way which follows a disused railway line to Hertford.

A kilometre before reaching the end we went off-piste to find the confluence of the Mimram and the Lea. Its at the end of a footpath to the east of the grounds of Hertford Town Football Club. I imagine that few locals even know its there and its a nice quiet place to mark the end of the trip.

Back to Chiltern Rivers Index

Cycling The River Mimram