Adding XC cycling in as a runner

Hey, adding another cycling & running question to the forum but appreciate any help! There’s questions about adding a few runs to a primarily cycling week, but this is a question about adding XC cycling in to running instead!

I’ve been a fairly decent runner for the last few years (16:08 5k, 2:38 marathon, a number of ultras, 67 VO2max) but I’ve gotten absolutely burnt out of the competitive element of running (struggling with the mental health side of racing, I think I’ve put in everything I’m willing to in the pursuit of performance at this point). I still love training, I don’t need races to go and train as I treat it as a bit of a personal experiment and do benefit from the mental health aspect of exercise. I also used to MTB a lot in my youth, and I’ve decided that there’s enough good trails and routes nearby to be explored that I’d get an XC bike and mix in some cycling.

With running I found a nice balance from 7 days/week, 120k-140k/8-10 hours, a big session somewhere between lactate threshold and lactate turnpoint, and a steady long run (pushing up to LT). The rest easy runs at least an hour long. In my head I imagine that (subject to weather etc) I’d swap at least 1 of the easy runs for a ride, possibly be able to chuck in another session on the bike too, and maybe swap the long run every other week for a long ride.

I have access to a lab to regularly test myself, so at some point in the next few weeks I’ll probably do a proper MLSS test on the bike too.

I don’t have the funds for a computer or power meter at the moment (the benefits of being a student are the lab access and constant physiological testing, the cost is being cash-poor!), but as mentioned I can still get the cycling-specific HR data and I have done almost all of my running with HR anyway. I’ve read that HR is a better guide for XC riding anyway?

So loads of words, thanks for reading! My question(s) are really seeking any thoughts/experience about balancing this training, any insights others have on doing similar, how does a run=ride - I’ve been assuming its about double (60 minute run = 120 ride). I don’t have any goals with riding, I won’t be racing but I’d maybe like to try some bikepacking/long distance epics. Really I just want to stay in good shape, have some fun with training, but also satisfy the nerd/scientist voice in my head that always wants to know the physiological underpinning of what training I’m doing!

I’ve found running vs cycling effort is somewhere around 3/2 or 2/1. Marathon roughly equivalent to a metric or full century. 10k roughly equiv to a one-hour crit. Obviously it’s nowhere near exact - terrain, RPE, relative fitness in each, etc. TSS doesn’t match up either. This is just perceived fatigue in the 12-24 hours after an event or hard training session.

For day-to-day training, the biggest impact for me is running takes more recovery than cycling. A moderate tempo run is enough to “ruin” bike intervals the following day. Maybe that would go away if I did more volume running? Dunno. I tend to massively reduce running volume if I’m training for an ‘A’ race on the bike. And rarely have target running races (I do race, but don’t treat any of them as ‘A’ races).

As for bike-packing, it’s a ton of fun, especially if you already enjoy camping and backpacking. I try to do several trips/year. Usually a few easy one-night trips with my wife and dog (she doesn’t mountain bike, so we’re limited to easy gravel or pavement). And a few multi-day off-road trips with friends. I don’t go crazy with the mileage - ~30 miles off-road, maybe a bit more - I enjoy the hammock time at the end of the ride as much as the ride.


I mix up running, cycling, walking and weight training. Do track nights, mtb rides, cx etc as well as lots of bimbling around the countryside.
Frankly it’s lovely! I’m in training heaven and it all makes me pretty fast but more importantly KEEN when I go to races.
I’ve done the whole train properly, race seriously thing. It’s great until its not eh?
P.S. Nothing beats multi day bikepacking for making you hugely fit.

100% - I’ve lost the drive/put in as much as I want to in terms of chasing seconds now.

Went out on my first ride today and looking forward to adding some more volume and more exploring via the bike!