Speed improvement from MTB to road bike?

[Recess]

Hello.

I'm apparantly a competitive fellow. I say apparantly as I've never really cared about exactly how fast i can go, or even how far I can go - and for sure not how fast I can go over a certain distance.

That was until my sister in law told me she did 10 miles in 27mins at a time trial (she's rather good I imagine). So now, I suddenly feel the need to be faster, stronger, and better than her.

My question therefore is this. My Giant Terrago MTB isn't (obviously) the most suited weapon for my war - even with slick tyres instead of nobblys and an improved rear cassette. However, I did a 13k hilly circuit yesterday (in the rain) in just over 26mins, leading me to estimate around 2mins a K for my ride. As that'll give me about 32 mins for 10 miles, how much am I retarding my improvement by not buying a 'proper' road bike for my quest?

I know training has a lot to do with it - and as I've got a 26 mile commute every day, that's 75% taking care or itself - and I purposely rode with a shagged rear hub so I would work harder - but if I used a bike more suited to the job, am I likely to shave minutes off my time instantly?

If you could all send your answers to my wife, so I can convince her to let me buy a good bike (got my eye on a Trek 5200 right now) I'd appreciate it.

Seriously though, what kind of improvement would be seen between a MTB and a road bike?

Thanks in advance.

John.

[kuan]

OMG that's the lamest most ridiculous grovel for a new bike post I've ever read! :D

Just buy it. This is a test of your marriage you know. If you get divorced over a Trek 5200 then you know the marriage wasn't going to work anyway. ;)

[BloomBikeShop]

If you setup an MTB with narrow slicks, bigger gearing, no suspension, and an aero position, it will be pretty fast. Not quite as efficient or comfortable as a road bike, but still pretty fast.

But going to a Trek 5200, well, it will feel much, much better :)

[pista]

Just get any real road bike you can afford. As long as not from Walmart. Any road bike will go faster than any mountain bike. My mountain bike weights twice as much as my road bike and the gear is all wrong for road riding.

Get a bike that has at least 105 Shimano gruppo. And you should be set.

[DylanJ]

I ride a 30 mile course (railroad grade 15 miles there, 15 miles back). I used to use a mountain bike and my fastest time was 17.0 mph up and 18.4 mph down. Otherwise I usually averaged about 15.5 mph. On my new road bike, the 4th time I rode it, I got 18.6 mph up and 21.4 mph down. The averages get dragged down by stops and traffic. So I'd say 21 mph on my road bike compares pretty closely to 17 mph on my mountain bike in terms of effort to sustain. I used to average just under 2 hours and now, if I push it, I can average just over an hour and a half, so the difference is quite significant (20% efficiency boost, approximately). Hills will just make the difference bigger for road bikes.