So what am I doing wrong?
 

I got back into cycling two years ago by buying a Trek Navigator 2.0. Through the past two years I've replaced the seat (Specialized BG Sport), raised the seat, lowered the stem, and swapped the tires out for 1.5" inverts.

This year I took the plunge and added a "faster" Trek 7.5FX to my line up. The problem is, I'm only getting 1mph faster average speeds per trip with the new bike. Yes, the computers are set-up for the correct tire size on each bike (both computers are Specialized Speedzone Elites), and and I'm riding the same "course" (10-12 mile with stop signs and lights), and I've been out in comparable weather.

I was getting about a 15MPH computer average (with all of the stop and goes) last year at the end of the season on the Navigator. This year (despite winter trainer miles) I'm getting about 13.5 on the Navigator (including a grocery run with panniers), and 14.7 on the 7.5FX.

Is it possible I'm pushing too hard with the FX because I think it should "fast"? I don't know how much of a speed increase I expected, but 1MPH wasn't it. My thighs seem to feel tighter after a ride on the FX, than they do on the Navigator - could it be that I have to get used to the new geometry?

Any suggestions would be appreciated.

Thanks, Rob

http://bikeforums.net/attachment.php...hmentid=146440

I think you are not alone. Last week i was looking at the new made ,but old style steel ,English Pashley bike site. A 40ish guy did a 5 mile time trial with his very light carbon 27 speed bike and a twice as heavy 3 or 5 speed internal hub Pashley Guv'nor. The carbon bike won by only 24 seconds and .7 mph. 22.6 to 21.9 mph. Page 4 or 5 in the owner photo testimonials. I seem to have similar cruise speeds on all the bikes i have used. But i never had an expensive bike. Your fast bike seems to have a smaller post angle? And taller also.

So, if you put an engine in a VW Scirocco and drive it on a course, then put the same engine into a VW Jetta that is geared the same as the Scirocco and drive the same course, would you expect a much higher average speed with one compared to the other?

Maybe you should work on a bigger engine.

I think 1 mph is respectable and normal for a major bike style change. basically my avrg speed hasn't changed at all since I was a teenager on my 1st 10-spd about 35 years ago.

also - how do you calibrate your computers - the most accurate is by doing a rollout. you need to have the most accurate calibration on both bikes to an accurate assessment.

given the same engine theory a 7% increase sounds darn good.

you wanna make it even faster put drop bars and narrow 700x 28c high pressure tires on it.

I did that to my hybrid with Armadillos and they aren't even fast tires. I don't have empirical data on the speed difference but it runs like a road bike now and not a hybrid. I totally piss of the road bikers when I pass them with this bike

but when I realized speed was what I was after I bought an actual road bike (which really isn't much faster than my roadified hybrid!)

Are you comparing end-of-season times with start-of-season times?

The two most important contributors to speed are going to be the engine and aerodynamics. The big downside of the upright posture of these kinds of bikes is that it doesn't put the rider in an aerodynamic position.

If the rims aren't too wide, you might try narrower/higher-pressure tires (which won't be as comfortable).

Here's a way of estimating how changes will effect speed.

http://www.noping.net/english/

Using the default rider height/weight and a power-output of 160 watts.

Narrow tires: 16.1 mph with an upright posture compared to 18.1 mph
Touring tires: 15.1 mph with an upright posture compared to 16.6 mph


It's unlikely that your short 10-12 mile rides are going to help you get much more speed.

I think this is part of your problem. A course with starts and stops is not a good choice for isolating the speed difference between the bikes. Your average speed on the course will be determined by the starting and stopping as much as anything else. Looking at the two bikes in your picture I'm not sure there should be a big speed difference if the suspension fork has a low loss lockout function. I'd try to find a test course on a bike trail that has no stops at all and then make several runs on the two bikes alternately on the same day to try to eliminate as many other variables as possible. Obviously your engine will tire during the test process but differences between the two bikes should stand out as a change in speed from one run to the next in spite of the general loss in speed as the engine tires.

Ken

Thanks for your replies. I guess I just need to scrape more of the winter rust off (mag trainers are not like the real world), and realize I won't get a speed increase of any great magnitude. The FX will still be more efficient for any long rides I may do this year, and climbing with it is so much better.

No I'm not comparing end of season to start of season, I'm comparing results this week.

The gearing is different between the bikes, the Navigator is 14-34 on the rear, and the FX is 11-26.

I did a roll out calibration of the inverts on the Navigator, because the programmed tire sizes didn't match. The programmed 700x32 seems to match the tires on the FX (compared to distance results from the Navigator).

As for any changes to make my hybrid more "road" like - I chose to forgo those when I made my decision between the FX, and The Pilot series. I just didn't want a road bike (I don't like the hoods, and I'll never use the drops). If I have to give up some speed, I guess I'll live with it. The FX already has 700x32 110psi Race Lite Hardcase tires, maybe when they wear out I'll try 28's - I'm still getting use to the handling on the 32's.

Rob