Cycling as part of marathon training

I´m training for marathons and apart from running 4-5 times a week also cycle to work 5 times a week. It´s 9 miles each way with varying speed (due to city traffic and terrain - some in heavy traffic, some through Richmond Park where I can go much faster). It normally takes me 30-35 mins. How much of it can I count as part of my weekly mileage for running? I.e. If I aim to run 50 miles a week, can I take 10 miles or so for my cycling?

In the oct/nov issue of Trail running magazine there is a 13 week training plan to run a 40 mile race, and some weeks after a 12-15 mile run on a sat you have to do a 21 mile bike ride on sun. Which they say is equivalent to a 7 mile run! The principle behind it is "periodisation training-controlled overloads to help strengthen heart and lungs and to get the body burning fat mor efficiently" hope all that makes sense! 

if you want to run faster run more (without getting injured).

You won't find Mo or the Kenyan's cycling.

But Petr hasnt said he struggles with injuries. He's got a plan of running 50 miles per week, but wants the bike to account for some of those miles.

He'd be better off having a plan to run XX miles and then just ride on top of that ?

He's doing about 5 hours of cycling a week.

50 miles of running would be what - 7 hours or so ?

If we go with your 2 mins of cycling is worth 1 min of running - he'd knock that down by 2.5 hours  - so down to 4.5hours  - which would be under 32 miles.  A long way off running 50.

If I ran 50 every week I'd be flying. 

As it is - I'm usually nearer the 32 but with cycling on top. I'm not flying.

I've heard Kenya will be the next cycling nation - but I'm not sure. Its a lot more accessible to run than it is to get a bike. Plus I dont think the Kenyans would cope with cold rainy Belgian cobbles.

(then again I never thought we'd see a Brit win the Tour)

I'm thinking along the same lines as YP.  Presumably you've been in the cycle commute habit for a while so it's well within your comfort range.  However, when you start ramping up the mileage for marathon training it could take while to get used to the higher overall volume of activity, in which case you might have a case for dropping the odd easy run, and considering the cycling as useful cross-training before you feel ready for your next big running effort.

That's another thing - not all running miles are equal, which is part of the reason why it's a little misguided to think about running/cycling mileage/time equivalents.  There's absolutely no substitute for time on feet for marathon training, so if there are any compromises on the running mileage it should only be cycling in the place of shorter, easy runs.  Make sure you still get all the long runs in.

Thanks, guys. A bit of a mix here but helpful. Cheers!

I'm in the camp that thinks that cycling can replace some of the easy "recovery/filler" mileage. Make sure you have the Sunday long run, midweek longish run and a couple of quality sessions - they cannot be substituted by cycling.

@ULTRA - I agree with you. especially your first comment.

for the others yes prob 2 mins of cycling is like 1 minute of running in terms of difficulty BUT as @ULTRA says its different leg muscles. But yes of course both use the same lungs and blood and other various bodily bits and pieces. So maybe's everyone is kinda right??!!??

FWIW I do a lot of cycling and a lot of running......

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I'm with Dr Dan  - cycling is good for replacing those easy and steady runs, and also for recovery so can be used to make up the miles, but for marathon training in particular you can't substitute the weekly long run or long tempo and speedwork. By replacing some of the easy runs with cycling  though, it does mean you can increase focus and effort on your critical sessions and make those work much better for you.

The cycles sessions need to be of a good quality though and stretching you aerobically.

Sussex Runner (NLR) wrote (see)

RW published a book about 3 runs a week and 2 cross training sessions a week and how runners doing this thrived on it. A cycle is different from a run but there would be no point cross training if it wasn't.

Run Faster, Run Less. Basically all 'easy' mileage is replaced with swim/bike/row. So you could follow the plan without cycling at all.

I subscribe to the thought that if you own a bike there is never any need for recovery run mileage.

More to the point who said you need to do 50 mpw to complete your marathons?

I have been knocking out 3.30 mara times off 25mpw runs and around 100 miles on the bike.

Everyone is different though i suppose its up to you to experiment.

I ran 2:46:51 in the 2003 Abingdon marathon off cycling and averaging 18 miles/wk running for the six months preceding it.