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I am currently riding an entry level carbon road bike (Fuji Gran Fondo 2.5, compact 50/34 crankset, 105 group, 12/30 10 speed, Oval 327 wheels, but I suspect the details are not important-you have all seen similar bikes on club rides) My typical ride is 30 miles and 1500 feet of climbing (as reported by Strava, if I add up the hills they are not this high) in 2 hours, so I am not a speed burner. The Gran Fondo is promoted as an "old guy's" (which I am) bike-the head tube is a bit longer (only 1/2 inch) than standard so you sit more upright, you get (my year, not now) the 30 tooth on the rear and the tires are 25 instead of 23. Will another bike blow me away if I ride it a short distance (5 miles) on the flat? How much time can I save at the same power input over the 30 mile ride? Let's pretend I have no budget limitation, I just want the fastest (easily available commercially) road bike for my use. How much faster is it than what I have? What would you look for? Don't send me looking for an 11 tooth on the cassette-I rarely use the 50/12. You need to send me to a class descending hills faster first.

Added based on Craig Hicks answer: I have inverted the stem, which probably counteracts the longer head tube of the bike I have. I didn't notice any difference in comfort. I could take a couple spacers out of the the head tube to lower the bars another inch. I did a high end fit with my LBS with some comfort improvement but no speed. I suspect the biggest speed increase I could buy would be race tires that have less rubber so less flexure loss on the road at a price of durability. That is what I was looking for, what should I look for and how much would it speed me up?

  • With all the acknowledged issues with Strava's power estimation, what power does it say you produce at 15mph (24kph) on the flat? – andy256 Jul 31 '15 at 3:48
  • @andy256: I did a flat ride just the other day of 17.4 miles at 16.9 mph (per Strava-the upload lost the first mile) which it reports at 140w. Maybe it was a bit faster, but this is the ballpark. There was some flat trail without obstacles at 20mph or so. No significant segments over 22 mph. – Ross Millikan Jul 31 '15 at 3:59
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    It’s probably more a matter of seating position than cost of the bicycle. Seating position can greatly effect aerodynamics and (to some extent) efficiency. Weight reduction and more aerodynamic wheels will help, but not all that much. For potential in weight you can use kreuzotter.de/english/espeed.htm and play around with the bicycle weight. – Michael Jul 31 '15 at 16:37
  • Are you willing to wear a pointy helmet with full face shield? – jqning Aug 4 '15 at 17:43
  • You can buy a hidden bottom bracket motor that would fool even some UCI judges. I’m assuming they go for at least $20,000 in engineering costs. – RoboKaren Dec 18 '17 at 17:00
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You can plug some numbers in http://bikecalculator.com/ or http://kreuzotter.de/english/espeed.htm (thanks @Michael) and see what they say.

Juggle the figures (your weight, bike weight, etc) a bit until what it says matches your results.

Now guess the weight of a new bike. Not much speed difference huh?

Now assume that the better position, transmission, wheels and tires add 10 watts to your effective power input. That will probably add about .5 to .6 mph (1kph) to your speed. Check how position changes the results!

Now add the I got a fantastic new bike factor. Figure that at another 10 watts. Your guess is as good as mine. So you'll probably see 1 to 1.5mph (1.6 to 2.4kph) improvement for short rides such as you describe.

Now you've scientifically demonstrated (with known assumptions) what you'll get for your money. It might be better to just train more.

But if, as you say, pretend I have no budget limitation, then go for it. Follow the N+1 rule.

  • I am a strong believer that bicyclists are too interested in weight. My bike is listed at 19 lbs (probably 21 on the road with pedals, tool kit, and water bottle). The shop has one at 13.5, but if you add me at 165 the difference is small. On the flat, who cares? That is easy to calculate, but position, wheels and tires are harder to assess. I am surprised that rolling down gentle hills on club rides where others are pedaling I am braking to stay in position. But 1 mph is enormous. At my speed, wind resistance is not as big a deal as for faster riders. I can train more on either bike. – Ross Millikan Jul 31 '15 at 5:12
  • I think we are on the same page. In essence, I am asking what the increase in speed at constant power is, and flat ground is a good standard. The calculator you link has some model for rolling resistance and wind resistance which is not evident. Clearly both are a function of the bike, though you can position yourself on a given bike to reduce the wind resistance. It's not easy. I could say there is a given trunk angle that is the minimum I would accept, but lower bars will encourage bending over more, reducing windage. – Ross Millikan Jul 31 '15 at 5:23
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    In your question you asked about speed, but there's no underestimating the joy of riding a nice tight new bike :-) – andy256 Jul 31 '15 at 5:24
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    We have long known what it takes to go faster: either increase the power you can make or reduce the power you must make. If your power output is fixed, you're looking at reducing the power needed to overcome drag. That means reducing rolling resistance, aerodynamic drag, and efficiency losses. Compared to typical tires/tubes the best can reduce the coeff of rolling resistance from perhaps .006 to perhaps .0025. Drivetrain efficiency can be improved from typical 95 or 96% up to maybe 97%. Aero drag on a standard bike can be reduced from perhaps .4 m^2 to under .3 m^2. – R. Chung Jul 31 '15 at 15:07
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    One more thing concerning bicycle weight: It’s not that unimportant. Enter a 10% slope, change from a heavy 10kg bike to a light 5kg bike and suddenly you’ve gained ~5% speed without changing anything else. Of course this is a rather extreme example, but still almost a gear higher on steep slopes. – Michael Aug 1 '15 at 6:44
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A bicycle in and of itself is a half of the equation. If you want to eek out as much speed as you can you also need to consider how you interact with the machine. This answer focuses on the human/bike interaction rather tweaking bike specs.

Bike fit is a continual compromise between power, comfort, and aerodynamics (Bike Fit by Phil Burke). Simply plugging specs into a worksheet will not give you insight into these types of compromises. New high-end bikes can be problematic as they are often very aggressive. As you get older if you compromise the comfort dimension too much your power can drop of substantially. You may be more aerodynamic, but you can end up slower due to a drop in sustainable power!

Flat Land Speed

In terms of absolute speed on flat cutting down your frontal area (i.e., aerodynamic drag) will go a long way to increasing your speed. There are lots of little tweaks you can do to your current setup if it is currently fitting you well.

  1. Tighter fitting clothing (any flapping clothing = aerodynamic resistance).
  2. TT bars are another big aerodynamic gain (don't use on a group ride though).
  3. Supple fast rolling tires pumped to the appropriate pressure. (This isn't always the max pressure and can change from tire-to-tire. You really need to experiment here)
  4. Tweaking your current position to further optimize the aero/power/comfort relationship.
  5. Drive train gearing
    • Tighter gearing ratios (aka a smaller range in the rear cassette). This can let you fine tune your cadence more.
    • Big/big combinations are more efficient that Big/small gearing combinations for a given chain line.
  6. Maintaining your drive train!

Climbing

Here a lighter bike will help, but also more appropriate gearing is very important (aka low enough to spin up all the climbs). As Andy256 suggested you an play with some calculators. But again I will harp on bike fit. Do you have the hand positions available to put you in a open upright climbing position so you can breath properly? Are your shoulders, neck and back relaxed on climbs. Do you have enough hand positions (i.e.,drops) so that you can comfortably get in the drops on decent and faster sections.

Going up to get down

One day I finally admitted to myself that I could not ride the slammed positions of my youth and revised my cockpit putting myself in a more upright position. The result of this is that I am much more comfortable on the hoods and can crank out the climbs at a harder pace. I can also use my drops a lot more now as the higher hood position this give my back a change of position it now needs. My drop position is still quite aerodynamic position and I can spend a lot more time in the drop position than I have been able to in the past. Overall I don't think my aerodynamics has been too adversely affected as I am using the drops a lot more than even when I was younger (then I used to just use them in crits, sprints and pursuits). I wish I had taken more measurements when I was younger to confirm or refute this thought.

I suggest taking time to investigate how bike your current fit compliments your bio-mechanics before delving into the quest for new gear. You might be surprised how many gains you can find!

  • True and well explained, but it doesn’t really answer The Question ;) A lighter bike and aerodynamic wheels will certainly help, it’s not only about the fit. – Michael Aug 1 '15 at 6:31
  • @Michael - While fit may not be the whole answer it is often a huge component. If money is no object (as you suggest) I would consider professional fitting in a wind tunnel. If you can reduce your drag coefficient, yet remain comfortable this could be huge gain, potentially much bigger than a lighter bike and aerodynamic wheels. How big depends on the pace you can ride at (the gains are multiplicative relative to speed). To me changing some bike specs such as weight and wheels is a very one-dimensional approach. – Rider_X Aug 1 '15 at 16:20
  • @Micheal - The market is over skewed towards the advantages of expensive hardware of various kinds, because it generates large profits. A lighter bike and aerodynamic wheels do not -necessarily- help at all. The answer to what is suitable can only be answered in the context of riders weight, fitness, fit, type of intended riding, etc. And as I mentioned in an answer below, the proper "fit" itself changes with the power the rider will be outputting, so that a long endurance ride requires a different fit from a short high power ride. – Craig Hicks Aug 4 '15 at 20:16
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I like andy256's suggestion a lot, but I must add some. The way I see it more money will buy you either or both two things that affect your speed (1):

  1. Less weight.
  2. Less power loss between pedals and road.

Andy 256's link will easily let you vary (1) directly to see what it gets you, to vary (2) you need to change the watts figure you input at the top within a reasonable range. I'm not sure what the total power loss between the pedals and the road for a typical bike is, but my gut feeling is that an entry-level road-bike such as yours will have about 90% transmission efficiency (assuming good maintenance, proper tire pressure, etc.), doubling to quadrupling your spend will get you to about 94%, and I think the absolute limit is in the 95%-97% range. The top end I base off of the fact that a good transmission system alone has a transmission efficiency of about 97%.

If absolute speed is your goal then I can think of some ways you might also spend your money (and time) other than a more expensive bike to achieve that (and some unconventional bike options).

(1) It will also buy you more or less durability, easier or more difficult maintenance besides a host of less tangible/certain benefits depending on how much you spend and what you spend it on.

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    Beyond about $1000, more money generally buys you less durability and less ease of maintenance. – Daniel R Hicks Jul 31 '15 at 16:24
  • In this context, yes, but It depends on what you spend your money on was my point. You could also spend for durability (40 spoke wheels, titanium frames) or ease of maintenance (rohloff speedhub, belt drive). Or just one a flashy custom powdercoating for your entire bike (for no tangible benefit whatsoever). All these will get you beyond $1000 easily. – jilles de wit Jul 31 '15 at 21:23
  • +1 for mechanical doping. Seriously, if money is no obect and all you care about is going fast, then a motor is probably a good solution. You could probably get a Trek Emonda SLR 10 which weighs in at 10.25 lbs, and not even get close to the gains that a motor would give you. The real answer to go faster is to have a decent bike and increase your fitness through training. But if you want to throw money at the problem, then a motor cannot be beat. – Kibbee Aug 1 '15 at 17:20
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Probably your bike, as an entry level bike, allows you to sit in a -relatively- upright position. This is probably a good thing! It takes a lot of training and practice to build up the muscles to ride in lower position - and as one ages (ex-pros included) it gets increasingly hard to maintain a low position. If you try to maintain a lower position than you are capable of - you will go slower not faster. You will feel tired and uncomfortable, suffer neck, back, arm, and hand pains. You may end up riding less because it is so painful. The more pain you feel, the less power you will output, which will result in more weight and pain on your hands, in a kind vicious circle.

Is your stem currently in the upside down position? If not, try putting it upside down (e.g. -6 instead of 6) and see how it feels. You might try putting it at -6 and doing HIT (high intensity training) for as long as you can, then change back to +6 for a more leisurely ride.

Of course if your fit is not right to begin with now - then you benefit from a better fit. But that is not a bike quality/expense issue, it is a fit issue. And again I emphasize, the correct fit changes depending on power output / length of ride. (I have two bikes, a carbon fiber with with a low position for power rides less than 3 hours long, and a steel cross bike for everything else. I guess its an older cyclists version of reading glasses and driving glasses!)

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