02Giant 

It would be more cost effective to dangle a doughnut on a string in front of your bike.

kbarch

I think the consensus is pretty clear: Old road vs old mtb - appreciable, but not a whole lot; old road vs new road - nominal at best. Maybe you were hoping for a less vague answer, but in either case, the differences are relatively small and highly individual, so they aren't quantitatively predictable with any reliability.

rpenmanparker 

And don't forget that some of the speed difference between MTB and road bikes is due to rider position/aerodynamics, not the speed capability of the bike. Then add on tire rolling resistance, even with slicks, and you have accounted for a lot of the difference.

banerjek

It doesn't matter why the difference exists, only that it exists at all. If you put 1" slicks on an MTB, you'll erase about half of the speed difference with a road bike, less on uphill climbs where the difference is better thought of as a percentage than in mph. Switching bikes won't change a slow rider into a fast one or vice versa, but you can still tell. Likewise, the riding position of different kinds of road bikes gives progressively smaller benefits that you can still perceive easily enough. There is also the fun factor of riding a cooler bike.

tycobb73

Its kinda what I thought and wanted to hear as I just saved $2000. Now if a major improvement came out I'd buy a new bike. The year v brakes came out I bought last year's model Klein without the v brakes. Kinda wishing I spent the extra dough on v brakes. And I know you guys will say put them on yourself. Being legally blind and having cerebral palsy makes me a bad mechanic.

valygrl

A new bike will be faster if it fits you better, puts you in a more aerodynamic riding position, or makes you ride more and therefore you get fitter & faster.

But, I think speed gains don't matter much, what matters for the decision whether & when to buy a new bike is:
- do you want a new bike
- will having a new bike make you motivated to ride more (because it's more comfortable or more fun or just works better)
- can you afford the bike you want without screwing some other aspect of your life financially

If you can say yes to all of these, go buy a new bike!

as for waiting for Xmas for tires- really? can't you just ask santa to bring the tires now?

Zuzus pedals

The only way to make a reasonable guess is if the condition of an older bike is known (i.e., how smoothly it runs compared to when it was new) and if the rider's position on the new bike will be exactly the same as on the older one. If an old bike is still in mint condition, it probably won't be noticeably slower than a new bike on level ground (assuming identical rider position). Well-maintained bicycles will go pretty much as fast as you can pedal 'em.

Having said that, a new bike probably will be faster without any additional power required from the rider (again, assuming identical position). But most of that difference is just due to less wear and tear on the components vs. the old bike. And I'd guess the speed gain is in the 0.2 to 0.3 mph ballpark. That's about what I've noticed on flat road when riding hard tempo in the drops on my 2012 Trek vs. hard efforts in the drops on my 1980 steel Schwinn clunker, and I bet a good deal of that is because of drivetrain wear and occasional brake drag on the clunker. Of course, I can climb steep hills much easier on the newer bike (it's 11 lbs. lighter for a start and has some bailout gears) and I'm much more comfortable on it. So these days, I only ride the clunker when doing winter shopping or if the Trek is getting an overhaul at the LBS. If I'm riding at 18-20 mph on the bar tops on either bike and go to the drops, I'll immediately pick up 0.8 to 1 mph in calm conditions (a little less of a speed increase if there's a tailwind and a little more if there's a headwind).

When I borrowed a hardtail MTB for a few months in 2011, my speed was 2-3 mph slower than either road bike at cruising speeds and about 6 mph slower when trying to "sprint" (and I use that term loosely when describing my maximum "speed"). The 48 x 13 top gear kind of limited fast riding almost as much as the knobbies, but the upright, non-aero position is the real killer as the speeds get faster.

Maybe, just maybe, shelling out the $$$ for highly-touted "aero" components will give you a small benefit (less than two seconds per mile?), but the money spent per speed gained is not favorable for almost anybody below the pro level, where a few watts saved earns back the money spent to buy them.

So from what I've experienced, if the position and comfort are the same, the new bike will probably be a few tenths of a mph faster on flat terrain. If it's lighter, it'll be much easier to ride steep hills and you'll be faster overall on longer rides with lots of medium rollers since you won't be mashing as much and burning matches throughout the ride on the uphills. If you get more than one full mph faster, it'll probably be because of a much better fit and more aero position, not because of the frame or components. Get a poor fit and you're liable to be slower no matter how "fast" the new bike is.

Up North

You will gain .754 mph per $1,000.00 spent. The mental aspect will out weigh the speed gain, I feel good I pedal more often, farther and faster. Your positive contributions to the local economy will make you feel better. Keep one thing in mind, money was made for spending.

Sullalto

Weight is negligible. Aero>>>weight.

If you're really worried, also use low crr tires and tubes. While making sure to have a clean, lubed drivetrain, and avoid cross chaining.

(Also, stay in the drops)

Shimagnolo

Doge

I know a lot that would take that deal.

StanSeven

I think so too. $10,000 for 7.5 mph. Or $20,000 for 15 mph. That investment makes me a world champion.

BarryJo

Before trying to figure out if a new bike will make you faster why not spend the next couple months working on things you can control, weight and conditioning, and measure your progress on the OCR before shelling out $2K on a bike that you may or may not continue to progress on.

godeacs

Now that is really hard to believe...<G> With all those variables...uh, uh...

pallen

If you already have a reasonably modern road bike, its not going to make you measurably faster. If you aren't riding competitively, who cares if you're faster anyway. What are your real goals? Getting more fit? Having fun with friends? Racing?

I have different bikes and they each have a different feel, but aren't really "faster". My Surly Pacer is heavy and steel, but I can and have ridden 12 hours on it because its smooth and comfortable. My Scott Foil is lighter, is crazy stiff, especially in the BB, and feels great on climbs compared to the Surly. I also have a Kona Dew Drop (officially my son's bike now). It has 36 tires on it now and is great for smooth trails and gravel roads.

A new bike can be more fun, for sure, but why? Because its fun to spend money on new stuff? Because you feel good showing up at a group ride on something shiny and new? Because you have the money, so why not?

Hypno Toad

To some comments from a few days ago, my average speed is a comparison of one rider (me) with many rides over the same route with different bikes. NOT a competition with other users - we can take that to Strava (oops, that's another wedge issue). Therefore, my earlier post showed there is a small difference from a heavier road road bike and a lighter road bike.

To the quoted question:
I have an old Marin mountain bike I use for winter commuting, comparing that bike with my summer commuter (Kona), using the same route (11-mile route). My Kona is an average of 3 mph faster than the Marin.

A couple points about the Marin, it's been converted to single-speed set up and runs with a studded front tire. Moreover, I use the Marin the worst winter conditions; therefore, it is a little unfair to compare with the Kona. Here's my data:

Kona: 7 rides averaged 16.1 mph
Marin: 8 rides averaged 13 mph

I would say 2 to 4 mph improvement from a MTB to a road bike is reasonable, but likely closer to the 2 mph improvement.

Tires for riding an unpaved shoulder.... hmmm. That is tricky. I depends on the condition of the shoulders. For my Kona I have the 28mm T-SERV, these work well on limestone trails and I did a century gravel ride with them this year. These tires hold up well and give me confidence on a lot of surfaces: Panaracer: Professional Bike Tires from Panasonic | Urban

Footnote for the average-speed-haters, I use Garmin and Strava, they track "elapsed time" and "moving time". It doesn't make a big difference on these rides, 1 or 2 minutes (less than 1 mph). Anybody that wants to beat the average-speed-dead-horse... post a link any one of the dozens of average speed threads and well go there to have this conversation. Otherwise, let's focus on the question the OP asked.

Doge

Bought an Aero SWORKs Venge Frame - Check
Had François (FMB) make customer 25mm silk tubular's with no coating on the side and ultra thin tread to reduce rolling friction. - Check
Chain is purchased from Friction Facts - Jason has certs its 5W below normal. It is lubed before each ride with Rock and Roll gold or Red - depending on weather - Check
We put a 56T on the front of the TT bike so not to have to use the smaller rear cassette - Check

As to lower weight making you go faster - it does. The OP did not ask if anyone cared or not.

rpenmanparker 

You do realize that the "r" in "Rpenanparker" stands for Ripley, right?

3alarmer 

...much more fasterer. There's a direct correlation between the cost of what you ride and your average perceived speed.

zonatandem

Not as fast as you hope . . .

OldsCOOL

Yes, and add 1.72psi in each tire.

Ghazmh

This is all good advice but why is it that when I ride my H2 fit Madone I average 17mph and when I ride my unloaded 520 I average 14.5 mph? Gearing? The 520 weighs a heck of a lot more than my Madone.

rpenmanparker 

Wind direction?

Doge

Buying a bike is like a health club membership.
If you pay a lot and use it - it is a deal.
If you pay little and don't - you wasted your money.

Weight matters. How much - depends on your investment into the sport.

StanSeven

Best insight in the thread