Just pondering on how much bigger my thigh muscles are going to get now that I've built up a loaded commute and grocery-getter bike. Now I have a pretty light road bike which seems to be good for going long distances with minimal effort and getting a nice sweaty, heavy-breathing cardio workout. And with the commute bike which now has a rear rack and Performance trans-it grocery bag type panniers, the bike makes my upper leg muscles work harder and seems to be more of a weight-training exercise.

Has anyone alternated between a light and heavy bike and seen a bigger improvement in overall training and endurance because of it? Also, does anyone load up their panniers with weight just to get more of a workout?

Also, if any of you out there are worried about the weight of a bike with groceries, it's not a problem at all even up hills. The weight is a non-issue unless you're not riding a few times a week.

I don't commute with loaded bags, but I do have a Hybrid and a MTB that are both heavier than my Roadie. I can definately tell the difference when I've been riding one of those for awhile, then hop on the Lemond.

I go from a heavily leaden ( with emphasis on the lead- 35lbs) commuter, which I ride daily a minimum of 22 miles and usually add on more with grocery shopping and other errands, to a relatively light old custom steel framed road bike (21 lbs).

I've often given thought to the same question you asked and here's what I've observed:

Commuting every day on a heavy bike loaded down with the stuff I have to carry definitely keeps me in pretty good cardiovascular shape and the legs stay pretty strong. But I am usually travelling at a slower, more moderate speed and am pretty consistent in how hard I am working. Unless I'm late or inspired I don't even approach my max aerobic threshold since in the morning I'm just waking up and on the way home I just want to unwind from my day. I do keep a pretty fast (80-90rpm) cadence on the bike, however, and I think that has some payoffs on the road bike.

When I get on my road bike in the winter, like today, and I haven't been putting that many road miles in I feel slower, more lumbering and the bike feels jumpy and almost too light. After a few miles I start to get my form and the feel for it and I can feel that I haven't lost my general fitness but really I'm lacking what I call "snap". I just feel like riding the way my body is used to- just plodding along- with not much speed. Hey, it's winter, I'm in hibernation mode.

When I'm riding more on the road bike in the spring, summer and early fall and I'm getting faster that's when I notice that my stamina has improved from doing the commuter every day. I can use the commutes as training miles either as a base or just "time on the bike" and make my road rides more specific for training- like intervals or hill work etc. Then I'll start mixing it up a bit even on the commuter and will find myself flying along in jeans and a t-shirt carrying 25 lbs of crap in my milk crate pounding along with the traffic at 25 mph every once in a while and that's really when it gets fun.

I commute on a 23lb bike with approx. 15 lbs loaded pannier (laptop, papers, clothes...) I have a few good hills along the way that similate interals. I beleive that commuting on this bike has really improved my conditioning overall. Certainly I feel it way more the next day than the days I commute on my roadie. If I commute the entire week on this, when I ride my 16.9lb roadie on the weekend, it feels like I really fly. Climbing the steepest hills seem effortless.

My wife bought me the Performance Trans-It Panniers for Christmas this year. I loaded them up with weights once on a training ride this year. Handling / braking was squirrly with the extra 50 lbs.

This winter, instead of riding on my trainer, I've been commuting more often on my 31 lb FS MTB with Nokian Extreme 294 when the roads are icy/snowy. These tires roll slower than the fully loaded commuter. I should be in great condition at the start of the 2006 roadie season.

T.J.

During the summer, I attach a Trail-A-Bike so I can drop off my daughter at day camp on the way to work. The Trail-A;Bike is about twenty pounds and my daughter 46 pounds. Although she helps pedal, it is very noticable at the end of the summer when I start riding without 70 pounds of trailer and child.

Paul

I roll around on a 3-speed quite alot because I like the ride. It weighs 40lbs. My Trek 830 weighs 36lbs and when dummy loaded for training, up to 66lbs. With my justbought Trek 520, it feels like I've been working out with a medicine ball! Resistance is good!

I think you will be surprised at how strong you become and how you will increase speed even with a loaded heavy bike.

Right now, you might be huffing and puffing and feel a little bit like granny gritting your loaded bike uphills, etc. However, you will get stronger and soon find yourself hopping on the heavy machine and quickly getting it up to impressive speeds.

I have had friends drive by me in their cars and call me later saying it was quite a sight to see a guy going fast with a loaded bike like it was just the way it was meant to be done.

Back to the original question, your legs won't likely get any bigger, though they may change shape from toning. For resistance training to really result in muscle growth, you have to routinely push through the anaerobic threshold, which is next to impossible to do while commuting simply because if you did, you'd very shortly fall off your bike as your leg muscles starved. What you are encountering is harder aerobic work, not what most people whom train with weights for bulk would call "weightlifting". Yes, you will get in better shape, and yes, you will get stronger, yes, your legs will tone but don't expect Lou Ferrigno thighs from a bike or any aerobic exercise!

Thanks, lots of food for thought.

Exactly.

I use a heavy mountain bike for 90 % of my riding, and I'm always loaded down with gear, tools and cargo.

When I go up north and get on the road bike with no backpack . . . I fly!!!

"Bicycling" magazine suggests that commuters regularly do some high speed spinning during rides to keep the "snap" in the legs. If your bike seems squirrly when you load it up for training reasons then you have the wrong kind of bike. Real touring bikes are made for such loads.

Commuting on my tank with heavy tires all winter hasn't done diddly for my endurance. After all it's the same distance. It has made me a monster sprinter.