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-   -   Why is my Trek FX 7.2 slower than my Trek DS 8.3? (http://www.bikeforums.net/clydesdales-athenas-200-lb-91-kg/907208-why-my-trek-fx-7-2-slower-than-my-trek-ds-8-3-a.html)

Jarrett2 08-13-13 10:08 AM

Why is my Trek FX 7.2 slower than my Trek DS 8.3?
 
I have these two bikes:

http://www.trekbikes.com/us/en/bikes...ss/fx/7_2_fx/#

http://www.trekbikes.com/us/en/bikes...eries/8_3_ds/#

The DS8.3 is labelled as a mountain/dual sport hybrid. The FX 7.2 is labelled as a road/fitness hybrid. The FX is lighter, has thinner tires, no suspension fork, no disc brakes. On paper the FX is the faster road bike with the DS being sort of a quasi off road deal; but for some reason I am consistently 1+ MPH faster on the DS than I am on the FX when riding on concrete trails/roads.

Any idea why that is?

ill.clyde 08-13-13 10:42 AM

Duh ... 8.3 versus 7.2! ;)

Rich Gibson 08-13-13 10:45 AM

Tire width, tire pressure, tread age, tread aggressiveness, gear selection?

10 Wheels 08-13-13 10:50 AM

Computer setting Not Accurate for the tire sizes.

rumrunn6 08-13-13 11:05 AM

2 Attachment(s)
my roadified hybrid w suspension fork is a darn fast bike. I haven't compared it to my road bike with exacting precision, but I wonder if it's tjhe geometry and the difference in my ability to apply horsepower directly to the wheels, that plus the gearing. I just don't know. but my hybrid might very well be faster.

Jarrett2 08-13-13 11:06 AM

Quote:

Originally Posted by Rich Gibson (Post 15956259)
Tire width, tire pressure, tread age, tread aggressiveness, gear selection?

DS Specs:
Frameset: Alpha Gold Aluminum
Front suspension: SR Suntour NEX MLO, preload adjustable w/lockout, 63mm travel
Size 21
Wheels Formula alloy hubs w/Bontrager AT-750 32-hole rims
Tires Bontrager LT2, 700x38c (80 psi)
Shifters: Shimano Acera, 8 speed trigger
Front derailleur: Shimano M191
Rear derailleur: Shimano Acera
Crank: Shimano Acera M361, 48/38/28 w/chainguard
Cassette: Shimano HG31 12-32, 8 speed
Brakeset: Tektro Novela mechanical disc brakes w/Tektro adjustable-reach alloy levers, 160mm rotors

FX Specs:
Frame: FX Alpha Gold Aluminum
Fork: High-tensile steel w/lowrider mounts, CLIX dropouts
Size: 22.5
Wheels: Formula alloy hubs w/Bontrager 750 32-hole alloy rims
Tires: Bontrager H2 Hard-Case Lite w/puncture resistant belt, 700x35c (80 psi)
Shifters: Shimano EF51, E-Z Fire 8 speed
Front derailleur: Shimano M191
Rear derailleur: Shimano Alivio
Crank: Suntour NEX, 48/38/28 w/chainguard
Cassette: Shimano HG31 12-32, 8 speed
Brakeset: Tektro alloy linear-pull brakes w/Shimano EF51 adjustable-reach levers

Both bikes have about 3-400 miles on them.

fietsbob 08-13-13 11:14 AM

Placebo effect.. :lol:

Jarrett2 08-13-13 11:20 AM

On my GPS?

ill.clyde 08-13-13 11:40 AM

Not to be an a$$, but why does it matter?

If you don't want to go slow, ride the faster bike. If you want to improve yourself, ride the slower bike until it's faster.

Jarrett2 08-13-13 11:56 AM

That's not an ass question. I'm trying to learn the differences in bikes so when I go to make my next purchase, I'll be better informed. Had I known this from the beginning, I would not have bought the FX, but rather the DS first.

philbob57 08-13-13 12:03 PM

Different energy levels? Different emotional states? Is the fit different? In getting back to cycling, I'm finding a change of CM in seat - sorry, I mean 'saddle' - height can speed me up or slow me down. Same bike, same rider.

MRT2 08-13-13 12:07 PM

Quote:

Originally Posted by 10 Wheels (Post 15956289)
Computer setting Not Accurate for the tire sizes.

That was my thought. Aside from the suspension fork and very slight tire size difference, the two bikes look almost identical. I would expect average speed between the two bikes to be very close. I made this mistake once.

ill.clyde 08-13-13 12:08 PM

Quote:

Originally Posted by Jarrett2 (Post 15956561)
That's not an ass question. I'm trying to learn the differences in bikes so when I go to make my next purchase, I'll be better informed. Had I known this from the beginning, I would not have bought the FX, but rather the DS first.

They're basically the same bike ... was wondering how/why you ended up with them

Jarrett2 08-13-13 12:11 PM

I tried adjusting the seat height as well to see if that was a factor.

A friend of mine was riding with me when I was on the FX and I was consistently faster than he was. He was riding a Marin Olena. He bought a Trek DS 8.3 and I immediately started having a hard time keeping up with him. He could also go off trail a bit without worry. That's what prompted me to look into them. I thought it would be nice to have a bike I could do non-concrete trails on, but once I started riding it, I found that it was consistently faster than my FX and have gone to riding it primarily with the FX as back up. Now starting to think about trading the FX for a road type bike, but also want to learn more about what makes a one bike faster than another.

ill.clyde 08-13-13 12:16 PM

It's hard to say ... honestly it could be any number of factors, many of which have nothing to do with the bike itself :)

I'd encourage you to definitely consider trading in or selling the FX if you're serious about "speed" and wanting to delve into road bikes.

squirtdad 08-13-13 01:08 PM

frames same size? geometry exactly equal? bars seat exactly the same position? your height on the bike the same.

I would bet that the bikes are not exactly the same and that your position is not 100% the same on both bikes

little changes can make a big differences if on the 8.3 you are a little lower (better aero) you might also have a slightly better bio mechanical position... and combined the two the give you the 1 mph difference.

I see a big difference 2-3 mph easy between my upright run around bike and my road bike

MRT2 08-13-13 01:08 PM

Sounds like a testimonial for the Ds 8.3. Though frankly you should be able to ride groomed trails with the 7.2. My advice is to take your time before buying another bike.

Jarrett2 08-13-13 01:16 PM

Quote:

Originally Posted by squirtdad (Post 15956860)
frames same size? geometry exactly equal? bars seat exactly the same position? your height on the bike the same.

I would bet that the bikes are not exactly the same and that your position is not 100% the same on both bikes

little changes can make a big differences if on the 8.3 you are a little lower (better aero) you might also have a slightly better bio mechanical position... and combined the two the give you the 1 mph difference.

I see a big difference 2-3 mph easy between my upright run around bike and my road bike

My only guess is its something like this. I guess I need read up more on ride fit.

10 Wheels 08-13-13 01:58 PM

Quote:

Originally Posted by Jarrett2 (Post 15956426)
On my GPS?

GPS is not as accurate as a properly calibrated computer.

2 wheeler 08-13-13 02:09 PM

Quote:

Originally Posted by ill.clyde (Post 15956611)
They're basically the same bike ... was wondering how/why you ended up with them

I agree.

If you're unhappy with the FX, get a real road bike to get some variety in your rides.


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