So its still wet, cold, and miserable outside where I live and it's nearly impossible to get on the bike outside. I do have a spinner bike that I can use to simulate biking but it's really boring and I get way too hot and theres really just way too many problems with it. My winter training has basically been running at the indoor track near me and I've really improved my running skills but I'm wondering if this will help me at all with my biking.

When I started running after the summer, my endurance had improved dramatically due to my time on the bike in the summer. I'm hoping the results will be reciprocal and help out my cycling. If you all are wondering, I am doing interval training as well as a lot of work in zones 4 and 5 heart rate wise when I run. Any feedback is appreciated!

Not as good as riding/spinning, but a lot better than doing nothing.

This (or at least this is what I've found).

Good, hard trainer sessions (ugg) and muscle training (legs, core) help me out.

I don't run unless someone is chasing me with a knife or gun...LOL...

What I've heard: Running doesn't help your riding, but riding helps your running.

I've heard the same thing. I don't really get it though. My riding definitely helped me with stamina when on my feet, I don't understand why running wouldn't help with stamina on the saddle...

Riding definitely helps the running. I believe the other way around is also beneficial -- different muscles and nice change of pace.

It seems to me that long-distance runners at least tend to develop thin legs, as opposed to building up the muscles used for cycling.
I would expect there are some running and cycling coaches out there that have a lot better handle on this question.

I think running will help you build and keep aerobic capacity but probably won't help you be a better cyclist. Also, better chance of injury which will definitely not help your cycling (speaking from experience here).

"Will running help my cycling?"

No! Running is evil, and it will never help anyone.

I'm respectably decent at both, being a racing triathlete for now. I spent 6 hrs per week on the bike and 4-6 on the run, pretty much every week, including speedwork.

If you want to get your BEST performance in cycling, just bike. Bike a lot. Specificity is king.

However, running will absolutely help your cycling (if it's not replacing bike training time) and vice versa. The one that will get more improvement is the one you are worse at, meaning if you're a bad runner, cycling will tend to give you bigger gains than vice versa. Lots of faster pure runners who come into biking later in triathlon, and they are never slow on the bike, even when they start out. Again, this is comparing adding running on top of whatever cycling you're doing - it will not be as effective for cycling gains as using that run time to cycle more instead.

In contrast, swimming, which has almost no overlap with cycling/running - you can be a star runner/cyclist and if you have no swimming background, and it has essentially no correlation on how fast you will swim or improve there. It's literally as bad as a novice athlete learning to swim. (I experienced this myself, and it was quite a shock.)

Your best bet to improve during winter on the bike in crappy riding conditions is to work hard on the trainer. If running were so effective for maintaining bike performance, I'd just ditch the bike entirely during winter and just run, since I'm good at running and actually enjoy it, but you gotta bike to stay good on the bike.

From my experience, running is a better cardio workout and will build up endurance for long rides but does not help with leg strength.

That kind of running will help with cycling but not as much as if you spent the same time and effort on the bike. Indoor cycling is boring but if you want to improve, try some videos to make it interesting. Or take spinning classes or find bike shops where you can do some competitive type indoor training sessions. Of course I'm saying this assuming you want to continue just with cycling. If you just want to build/maintain fitness, running is an excellent activity.

to my understanding, cross training will always help. Last year, I hadn't ran in at least 9 months. When I decided I needed to get some cardio in before day's end to prepare for the race next week, I went out for a 6 mile run. The entire next week, I couldn't walk right and struggled to stand up from a chair - legs were so sore. I stayed off the bike, even though I didn't feel sore riding it. The following week, I got my first win. go figure.

running helps your cardiovascular fitness but does little/nothing for the muscle group used when cycling.

Yes,yes,yes!I do both one every other day,,,non runners saying "I heard" says everything.They know nothing.

Winter cycling was meant to be miserable.

Yep. I can vouch for that. I was a runner before I started cycling this past summer. Don't have enough time for both.
Cycling helped improve my running and also maintained my running endurance level i.e. I didn't have to start from scratch to build up mileage.

Running will help maintain aerobic endurance will not help improve cycling ability.

+1. Started doing serious cross training with a personal trainer - free weights, abs and core work, lots of balance drills, boxing and tons of running through short "obstacles" on my toes. I'm 5 1/2 weeks in and I'm hooked. No, I'm addicted. My fitness has gone up so fast, my cycling group has joked I must be doping. I road pretty steadily most of the last 7-8 months of last year and kept improving a little but my rides since beginning the regular workouts (3 x's a week) have ben revelations. My lung capacity has always been a concern for me as I've only got one lung but I never knew how much I could push before because my legs would give out long before my lung would. Now, I'm starting to find a rhythmic breathing as a climb, because I've more confidence that my legs are strong enough to keep the pedals moving.

Strava has been fun to use because I'm really able to break down where I'm improving. I mean I'm no speedster by any means but I'm tacking hills now instead of just surviving them. I've noticed not only a (minor) speed increase going up regular hills but that I'm pedaling harder at a faster cadence. No doubt in my mind the workouts are making me stronger and better all around on the bicycle.

As as a side benefit, keeping a regular workout schedule while not easy on the wallet, has helped me transform my body in ways I never thought possible especially at my age. I've lost inches off my waist and thighs and I now have bicep muscles that people have noticed. I'm not like a body builder but I'm starting to resemble a really fit person. And the progress has made me think bigger, like maybe I can go all the way down to my best weight ever (at 26) and how much more fun it'll be to climb hills with 20 more pounds off me?

I get really bored on the trainer in the dead of winter. Running let's me keep some outdoor stimulation in limited daylight, and burns off a little of the cookies. It seems soooooooo slow on roads I ride...

If you're a cyclist, and don't enjoying running, then don't run. Simple as that. If you're looking to maintain (or even improve) you're cardio, and don't have rollers, there's tons of cardio workouts you can do at home.

I don't have a lot to go on yet due to the crummy weather here lately, but I started doing spin classes in Dec and on one of the few rides I did in Jan I felt really good, shaved 4 mins off a 42 mile ride I have done numerous times and all with a 10 bpm lower average HR. One ride doesn't mean much but I'm sure I would have been a lot worse off if I had just been sitting on my ass.

I will say I'm not real impressed with spin instructors. There are two that actually ride a road bike and do pretty good workouts but the others are pretty lame. I find that I often ignore them and do my own thing which usually involves a moderately high resistance and holding my HR around my anaerobic threshold for 5 mins or so.

If someone steals your bike and you have to chase them to get it back, then yes.
I see no other reason to run.

As runner for 35 years and still running, I began cycling more in past 6 years and at first cycling helped my running. Then as a started riding at times 100-200 miles weeks consistently my running form was a bit off and overtraining. I found you cannot do both a top level you must pick. This last August-September due to some running injuries I took off 2 months of running and cycled 1000 miles each of those months. My cycling improved much more. Now back to running only in the winter the biggest benefit for cycling is the endurance. I can easily go out and ride a 50 mile ride but to do it fast requires more specific bike work. To stay in aerobic shape running will keep you going but if you want to race and ride really fast you need to ride the bike. These days at almost 53 years old I cannot pound the pavement like I did 20 years ago but I can really ride hard on the bike no pounding. The problem with the bike is it takes more time and you can crash.

Moral is that you can go the distance on a bike if you have a aerobic strength from running but if you want to race a bike then you better practice racing on the bike. Not much different the Michael Jordan who found out rather quickly he was no baseball player based on his basketball skills.

Yup, pick a sport if you want to be good at it. Inversely, I'm training for my next marathon (in May), and part of that is reducing my time on the saddle.

I haven't read through all these comments, but I'm pretty sure running (or any form of exercise) would help anything and everything to varying degrees.