Commuting - Why isn't road bike faster than my MTB?

Hmm.. I took my road bike (OCR2) to work today, granted I blasted through the straight sections a lot faster, for some reason, my average speed going to and from was only about 1 mph faster for a 45 minute run.

Does anyone have any explaination why my 20lb OCR2 with 23cc slicks @ 130psi isn't that much faster than my 35lb mtb with 2" wide semislicks at 70psi and a derailler that's so misaligned it only works in the 4 highest gears? This is for identical weather conditions, mid 70's, little wind.

you are using a new road bike engine. you have to break it in before you can the engine is capable of high rpm's!!!!!! :)

Hmm.. I took my road bike (OCR2) to work today, granted I blasted through the straight sections a lot faster, for some reason, my average speed going to and from was only about 1 mph faster for a 45 minute run.

Does anyone have any explaination why my 20lb OCR2 with 23cc slicks @ 130psi isn't that much faster than my 35lb mtb with 2" wide semislicks at 70psi and a derailler that's so misaligned it only works in the 4 highest gears? This is for identical weather conditions, mid 70's, little wind.

hard to say. if it's in the city, it's cause there are red lights, and it don't matter if you're going at 17mph or 18mph when you gotta stop for 1 minute regardless. if u have a rack/etc., the weigh tmight not make a big diff either.

anyway, it's just cooler to go on a road bike.. :p

sd

There's also experience. You've probably got hundreds of miles on the MTB, and the riding position, crank length, gear ratios, shifting method, and overall geometry are so second nature to you, you aren't distracted and can just torque it. If there are lots of hills, then the granny gear might be a factor, too.

I just can't understand it cause I have the same amount of miles on the road bike as the mountain bike (differing by about 100 miles). I know for sure that I hit higher speeds and hold them longer on the road bike and the computer only counts the time when I'm actually moving.
There's a section of road about 2 miles long and the differential between the mtb and roadie at that section was a whopping 8 mph. All the other sections for the rest of the 10 miles differ by about 3 mph. But when I checked my average time and speed when I got home, it was nearly the same.

I do feel more comfortable on the MTB though, the geometry allows me to get out of the saddle and spin at 60 rpm in the big ring up hills while I'm in the middle on my roadie spinning it out at 90.

Do you have the same crank arm length?

Do you have the same computer on both? Each company computes average speed slightly different. My brother has told me that he has seen his average speed actually decrease while he was traveling faster than the current average. Different brand computers may or may not use the same start and stop point for computing average speed. One brand may assume that anything under 2mph is considered stopped while another requires a 0 reading for x many seconds

How does crank length change the speed?
I'm not sure how the computer calculates it but I'm considering both requires a 0 for more than 10 seconds.

If you have a longer crank are you have more leverage and can push a larger gear. If you are more inclined to hammer larger gears (i.e. accelerating from stops, climbing out of the saddle) the longer arms give you more leverage. If you sit and spin the longer arms tend to create a more choppy spin.

Watch the stop watch on your computer. That will usually give you an insight into what triggers the average speed calculator as the stop watch should stop also.

I just can't understand it cause I have the same amount of miles on the road bike as the mountain bike (differing by about 100 miles). I know for sure that I hit higher speeds and hold them longer on the road bike and the computer only counts the time when I'm actually moving.

That won't matter on an urban commute. The big loss of time will come from slowing down before and then re-accelerating after each red light. My computer does the same thing, and yet my average speed is entirely at the mercy of just how many red lights I cop. If you really want to see whether there's any difference between the respective speeds of the bikes, head for some country roads where there aren't any traffic lights.

1mph is fairly significant. For an 18mph average speed that is 5.5% faster - considering that you still have stop signs where you need to accelerate/decelerate, corners to slow on, etc. its quite good.

When I switched from mtb (w/near slicks) to a roadbike style bike my best average for my 9mi commute (using the same method you do of not counting stop time) went from 18.5mph to 19.7mph. I also expect that best time on the road bike to improve as I've only ridden it a couple of weeks and I need to acclimate to it.

Al

Also make sure your computers are calibrated using the roll out method with you on the bike and tires inflated to your typical riding pressure.
Al

I think chrisL's answer and mcavana's answer are particularly on-the-mark.

I'm not sure if this has anything to do with your case in particular, but lower pressure in your tires means the bike is bounced up and down less by small bumps in the terrain. This wouldn't matter if you were riding on the best-maintained of roads, but on pavement that's been around for a while, high-pressure tires are going to deflect some of your pedal energy into up-and-down motion instead of forward motion, while 70psi tires might smooth the tiny bumps a lot better.

I think chrisL's answer and mcavana's answer are particularly on-the-mark.

I'm not sure if this has anything to do with your case in particular, but lower pressure in your tires means the bike is bounced up and down less by small bumps in the terrain. This wouldn't matter if you were riding on the best-maintained of roads, but on pavement that's been around for a while, high-pressure tires are going to deflect some of your pedal energy into up-and-down motion instead of forward motion, while 70psi tires might smooth the tiny bumps a lot better.

Plus I have shocks on my mtb. :)
I can plow through most potholes and everything else in between.

But you'll also be compressing those shocks or underinflated tires with every step on your cranks. That will happen foe every metre of your commute, no matter the road conditions.

There are numbers of the side of your tire, telling you the recommended pressure. Ignore those at your tire's peril.

But you'll also be compressing those shocks or underinflated tires with every step on your cranks. That will happen foe every metre of your commute, no matter the road conditions.

There are numbers of the side of your tire, telling you the recommended pressure. Ignore those at your tire's peril.

The max is 80psi but I pump my mtb up once a month when it drops to 60, so for the most part I'm riding on around 70.
I actually made it in SLOWER today than I did on my MTB, I got clipped by the car and went down but that only took about 30 seconds off my time. Once again, little to no wind, faster/smoother route. And I counted the time with my watch instead of using the bike computer.

I got clipped by the car and went down but that only took about 30 seconds off my time.

you mention this so matter of factly. you crashed again?

you mention this so matter of factly. you crashed again?

Well *I* didn't specifically crash again, I mean not by my own fault. A car blew a stop and the weaker brakes combined with the poorer manuveurability of my OCR2 compared to my mtb, I ended up in the intersection slightly more than I should've, got clipped, not even sure if the driver knew cause he kept going and down I went with full brakes on, bike sideways, going 2mph. I unclipped during the fall so I got back up, bent my left brake hood back in position, and kept going. My knee's scraped up and slightly stiff but I'm ok.

Just to prove my point about traffic lights. Yesterday I recorded a higher average speed with a headwind than with a tailwind. Go figure.

Just to prove my point about traffic lights. Yesterday I recorded a higher average speed with a headwind than with a tailwind. Go figure.I figure it this way, I can ride at average-speed 30kmh for 3.5hrs,and the last say .5 hr at at 12kmh because of hills ect, my average is only going to be recorded at 10-15kmh aprox for the last section. Now if I ride 3.5 hrs at 30kmh in perfect condtions the total average would be 30kmh average speed for 3.5 hrs.