Is it possible to gain any discernible level of fitness through cycling?

When I was biking 200-300 miles a week and running 35-45 for Ironman I could hop in an ultra and do pretty well. Couple months of bike focus and I could do pretty well in cat1-2 races also. There is more crossover than you might think. You do need a minimum amount of running for it to be effective though. Trying to do running races on zero running is very painful. If you run at least 3 days a week you can be pretty darn fit.

I think cycling is more transferable for mountain running. I see a lot of mountain runners doing a fairly high volume of cycling. Running uphill, especially steep ones is probably more similar to cycling than running on the flat is.

I think you're thinking of Zwift.

I'm a very strong (competitive) cyclist, and it's always surprised me how little that translates to running, at which I'm good but nothing special--which is not to say that's everyone's experience. I don't think most people can become amazing runner through cycling, but, yes, you do get fitness.

25 miles a weekend is nothing. Most road races are around double that, and any serious cyclist will bike around ten times that distance in a week. Cycling itself isn't what's keeping your neighbor from fitness, but rather a straight-up lack of physical activity of note.

Agreed. Running 10-15 mph on the flat is not sustainable for a cyclist without serious training. But uphill running is more like a cycling effort.

It works great in conjunction with running. Like run 5 miles on Monday. Bicycle 20 miles on Tuesday, Wednesday, Thursday. Then Friday run 5 miles and repeat the cycle. Your legs will be fresh and your aerobic capacity will be through the roof!

Uh no, your aerobic capacity is your aerobic capacity. There is no magic transformation when you train more.

"Uh no, your aerobic capacity is your aerobic capacity. There is no magic transformation when you train more."

What? Not true There is a maximum capacity but when you train regularly you increase aerobic capacity among other wonderful things that happen in your body, mind and dare I say spirit?

Definitely. When I was in cycling shape I couldn't run worth a darn on the flats, but I could drop people on the hills, where the quadriceps kicked in.

The fittest I‘ve ever been is when I was racing bikes. Much easier on the body to crank out huge miles, and competitive group rides and busy racing calendars are a cultural norm vs running culture as an adult being a lot of solo miles and selective racing.

I have found that runners make great cyclists, but less common to see a cyclist be a good runner. I’ve chalked it up to a lot of fitness of cyclists being masked by group riding (stick in the middle and you can go 3+hrs barely breaking a sweat but Strava says you just did 60mi at 20mph), and the fit ones who could probably run solid times don’t have the correct muscle balance, can’t handle the pounding, or aren’t used to long steady efforts unless they are a good time trialist.

It’s largely contingent on what their background is. Many cyclists get into the sport later in their life (ie post college) in the states at least. A lot of them never ran much, so no, they won’t be good runners. I know people with national records/championships who are horrible runners.

That said, there are lots of good cyclists who ran track and doc at ,east until college and were pretty good. The cat 1 guys with that background…they’ll be solid runners on low mileage because yeah, a lot of the general fitness translates, and their mechanics are still decent from their running dies. I’d probably put myself in that category…far from an exceptional runner, but I ride at a high a high level and so can run respectable times off not a ton of mileage.

But give me two random cat 1 riders with the same power curve and there’s a chance one can’t break 20 in a 5k and the other can run 16-17 minutes off the bike. It’s just a different sport, but to act like none of the fitness carries over is naive imo.

I wasn't sure whether to include that information or not, but thought it was relevant for the beep test score. I was probably about 4.5w/kg FTP when I did the beep test, and even when fit my sprint isn't nearly good enough to contest Cat 1 races; I'm good at suffering for a long time though.

Aerobically it’s probably 4:1 cyclin:running miles…

And even then they aren’t the same sports so you’re not working the same muscles the same way and they each have different aerobic ability…

cross training is pretty cool, because it’s pretty hard to really understand. but the bro science of it is that you can sub cycling miles for running miles(easy mileage) as long as you are keeping a pretty consistent recovery cycle of running and cycling mix.
and even swimming… that’s why triathlon is pretty magical…

But also I’ve noticed that for these aerobic cross training benefits they only go so far because once you get into a long distance for any one of the sports you start to really drop off… like you need the vascularized sport specific muscle…

Triathlon itself is a sport, meaning the combination of the three different sports back to back increasing oxygen debt, is a different stimulus… I think triathlon is probably the best pace you could ever have… and you don’t even need to do more than bass workouts for any of these sports in triathlon… The most common rep for a triathlon is 1K…

But then you can get into how you need good high end speed for all three of the sports. What is the combination of the three sports I am very sure is a whole new aerobic stimulus.

I’m a cyclist and just started running again - it will be interesting to see if my fitness crosses over. I created a YouTube channel to document my running journey.

Seth run faster than 4 min pace so infrequently that the rare moment he does the Stans goes wild.

Remember, 3:33/km is slower than his marathon pace. And he paused his watch!

So many people run their marathon pace and even threshold, vo2max pace weekly but don't get praise the way Seth does. You wonder if his Strava followers follow other sub-elites and world class elites who run insanely fast workouts and volume week after week. To them, 1 hour of slower than marathon pace is something to behold. Geez, maybe find pro athletes on Strava to see how it's done or even decent sub-elites who knows what they're doing training wise.

Was posting on another thread. I think there's a bug in this site. Not sure how the post got here

I coach a hobby jogger group and had a few people bring their cyclist friends over the years. Typically, those with no running background struggle the first time because the movement is different and they waste energy just trying to do the running motion. They basically cannot use their aerobic fitness at first. So yes, your buddy might have to walk. But most of them pick up on it quickly and manage a proper track session after only a few weeks, depending on how good their sense of movement is. Improvement is much faster compared to complete newbies in endurance sports.

Agreed. I ran six days a week for 12yrs, then had knee surgery and took up cycling as rehab and never got seriously back into running. Now, I ride 5~6 times per week, and run probably once a month. My cycling fitness is great, but 10min/mile is my easy pace at running and I doubt I could run faster than 28min for a 5k. Compared to pre-knee surgery, when I was a consistent 18min 5k finisher. Cycling does not keep me fit for running.

Why should it? It is a different set of skills. Think of it it this way: not a single runner on this board could keep up with a Tour de France rider. But it is possible that some Tour riders could easily keep up with many of the runners on this board. Even some of the Tour riders who have retired- like Jens Voigt, who posts his Strava runs.

I ran for 15 years, and then tore my knee to pieces and had it surgically repaired. I took up biking after, and ride- at nearly age 70- around 5000 miles per year. I really cannot run any more as my back is damaged so the impact forces hurt me, but I can ride all day.

Fair . I'm at 3.8w/kg (when in form, i.e. not winter) and currently 16m50s 5km shape.

Agree with the other poster who said that while there's some crossover in fitness, cycling and running are different sports and ability at one is no guarantee of equivalence at the other.

I have been putting in big running mileage this winter and am interested to see how it translates to cycling ability come March when I get back on the bike.