big ring

[gavroche]

both my MTB and road bike have 48T big ring.
I can do a steady 22mph on my road bike and only 16 on MTB on a level road.
I know weight and tyre size will affect my speed. My MTB is a lot heavier and has large knobbly tyres.
My question is: would a bigger ring increase my speed as other road bikers pass me and If I try to follow them, I find that I have to pedal faster than they do, so I can't keep up with them.

 

[cyberknight]

both my MTB and road bike have 48T big ring.
I can do a steady 22mph on my road bike and only 16 on MTB on a level road.
I know weight and tyre size will affect my speed. My MTB is a lot heavier and has large knobbly tyres.
My question is: would a bigger ring increase my speed as other road bikers pass me and If I try to follow them, I find that I have to pedal faster than they do, so I can't keep up with them.

If you are spinning your legs at 90 rpm ,which is the average recommended speed and assuming you have a 48x 12 top gear then you should be getting 27 mph on your MTB and 28 mph on the road bike.

On your MTB you could fit slicks that would make it easier to pedal on the road .

Both your speeds are good going , maybe you need to learn to spin faster as i get 21-22 mph out of 50x17

 

[jig-sore]

are the rear cassettes the same ?? changing this is the easiest way to do it.

if the rears are the same as well then its all to do with the size of your wheels. with identical gears a bike with larger wheels will have a higher speed for any given RPM.

this if why some people like to include wheel size when working our gear ratios.

a bigger ring would increase your available speed

 

[2Loose]

Knobbly tyres sap speed and effort.
I roll a long way with little effort on my road bike, I roll less than half the distance with far more effort on my mtb.

Change the tyres to slicker versions and then you will be much closer to the same speed on each bike.

 

[lulubel]

I think you're asking if putting a bigger ring on your road bike would help you to keep up with other road bikes. Is that correct? You can't really expect to keep up with a road bike if you're on a mountain bike.

Yes, it would. But you need to be careful that the difference in the number of teeth between your small ring (middle if you have a triple) doesn't become too great. If it does, you'll get an uncomfortable step when changing between chain rings.

As an example, I have a 30/42/52 triple with a 12-25 cassette. In my biggest gear, I'm comfortable spinning at 30mph, but I can't keep up that speed for long unless I have a slight descent to help me.

 

[gavroche]

my fastest gear is 48-15 so I make it not so fast after all.
50-12 would be better although harder to keep going.

 

[festival]

Yes.

You have learn to spin before you can increase the gears (which you seem to have done) and still be fluid in your pedaling. This means in running terms you are not one paced and can react to conditions and other riders by accelerating while using bigger gears.