slow going down hill

[complience]

I seem to have a problem getting speed up going down hill on my road bike.
Im not sure if its a matter of gearing or what. Even with the use of a heart monitor to make sure im keeping my effort up, I seem to be falling short.

eg: Theres a local hill near me. Short but very steep, and dead straight.

On my Battered old "cant believe its still running" mountain bike my top speed is 71kph.

Whereas on my new Road Bike its 63kph max.

its got the Sora Groupset on with 21gears, 3 chain rings on front set, so I didnt think it would be a gearing issue.

Anyone else have problem? whats going on?

 

[mrjay]

I was beginning to worry it might be old age slowing me down, but I just treated my bike to new grease and bearings in the wheel hubs. Wooosh.

Am I being contentious suggesting that anything a cycle computer tells you should be taken with a pinch of salt. My old computer/bike had me going 5 mph faster than my new computer/bike which gets me there in a 1/4 less time. Go figure.

 

[dgregory57]

On my Battered old "cant believe its still running" mountain bike my top speed is 71kph.

Whereas on my new Road Bike its 63kph max.

I outpace many people on down hill stretches, even though they can pass me on flats and uphill with ease. The reason is that I weigh about twice as much as the average rider. So, I just have to ask... what is the weight difference between the two bikes? Is the mountain bike 50 pounds?

More seriously, there is a chance that your mountain bike does have extremely high gears along with the extremely low gears. I had a friend point out to me that I had gears on my bike higher than his road bike.

One other element just came to mind as well. Riding position... Perhaps something about the faster bike facilitates better eficiency that is most obvious at high speed. Perhaps something like saddle height.