Weight Difference and Speed
 

Hello,

For some reason the bike sites doesn't give bike weights. I am torn between a 2015 Trek DS 8.6 or FX 7.5. What I would like to know is what is the weight difference between the 2 bikes. I can see the Ds 8.6 would be heavier but by how much. And also which bike is faster. The both seem to have great gearing. But the DS front crank has a 48/36/26 and the FX 48/34. The DS seems to be more a terrain type bike but can be setup for road too. while the FX is manly road. Anyways if anybody has any experience between the two. info would be great

This is an apples to orange comparo. The FX is a rigid street bike with sporty riding position,the DS is an upright dual-purpose bike with front suspension. The DS will def weight more with the suspension fork,hydro disc brakes,and wider,treaded tires. Assuming the same rider,it will be slower due to the extra weight and drag from the tires. But it will also be more comfortable on bad roads,be better suited to off road,and be a better choice for bad weather(esp snow) riding. Basically,you're choosing a sporty coupe or a crossover SUV.

As for bike weights,manufacturers rarely give them because they're not set in stone. Different size frames will be lighter/heavier,components can change from what's listed,and things like tires have a range they can weigh. If manufacturers did post weights,you can bet there would be cheating like over in the motorcycle world. They'd weigh them without pedals,and prolly also without reflectors and valve stem caps,and would prolly go through a selection of tires to get the lightest pair.

I agree that it's annoying that bike manufacturers don't list weights; but I also agree with dynaryder who says that listing weights varies and that there would be cheating. You can always ask the dealer to weigh the bike for you and generally they're happy to do that; however, it would be good that some weight range would be available. It seems to me that a weight standard could be set - a medium size frame with pedals, etc. It seems funny to me that bike manufacturers are happy to give you all kinds of specs and geometry (much of which means very little to most buyers) but not include weight. I think they know that weight is perceived by many customers to be highly important (whether it is or not is another debate) and they don't want to gdet into that marketing game (I don't blame them).

once mass is moving weight doesn't matter.

If I remember correctly my 2014 Trek 7.5 FX weighed 23.5 lb. before I added any accessories.

Every bike shop should have a scale. I get mine weighed every time I take one in. I suggest having them weigh it stock first before you add anything- makes for a "ground zero" figure to compare.

Indeed, I am probably going to get a scale here for the house- not that I'm anal about weight, just curious ;)

Very few riders need to worry about a weight difference of a pound or two. Most riders (including me) could lose a couple pounds and have the same effect as a lighter bike. Focus on the fit of the bike, riding position and your intended use for the bike (roads versus trails). And then enjoy the ride.

If 'speed' is important the FX 7.5 is the better choice. Suspended forks are nice for comfort, but are slower because of weight and lost energy in compression of the suspension.

Additionally, you can do what I've done, get a collection of 6 bikes so you have a bike to go with the mood of the day. :)
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Private pilots will discuss spending chunks of change to increase the gross weight, and therefore the payload, of their planes to carry more fuel and other stuff. usually on the order of 10 to 100 lbs. Inevitably someone chimes in and says if they (and their usual passengers) would get in shape and drop some pounds that would be the no-cost and most beneficial way to do it.

I'm looking at 20" frames. I don't like heavy bikes. Yes the DS will be heavier. But just wondering the difference between the two. I'm more concern if my wife can lift the bike. When i'm not around. We both had 30lb bikes before. She has a little harder time handling it. And as for myself I think lighter bikes are quicker on the road. If that makes any sense

Well here's my statistics from Veloviewer.

I've done around the same distance and time on both my DS and my CX bike. Now I know the CX isn't a performance road, but it's drop bar and about 5-6 kg lighter. Both bikes have been used for a mix of commute, short ride, long ride, dirt, trail..... Not a big difference in average speed (1.6kmh) , AND I've been fitter while riding the CX rather than when I was a complete out of shape newb on the DS originally.

What's my point...I dunno, just an observation :) I just ride :)

http://img.photobucket.com/albums/v4...ps02c6e338.png

The Trek 8.6 DS weighs in the high 20s, somewhere over 27lb. Once you add your cycle computer, lights, saddle/frame bag ( plus contents) drinks bottle etc. The whole bike will be over 30lb in weight.
Even still, its a great bike and fast enough.
The FX will be around 3-4lb lighter. But still not really light.

You should test ride both bikes. The narrower rims and lighter wheels on the FX may make the FX accelerate faster. Don't worry too much about weight; speed is mostly determined by the quality of the engine.

What kind of roads do you plan to ride on? And the 28 tires/wheels are not great for curb hopping.

i own a 7.7fx and spent 2k on upgrades from ebay. the upgrades cost more than the original bike. if i went to my Lbs and did the same upgrades it would've been 3500. there has been a dramatic increase in top speed, average, fun and overall ride comfort. i'm a light weight rider at 154 pounds @ 44 years young.

http://img.photobucket.com/albums/v2...psbb486733.jpg

above is a image of my very first group ride EVER. vero beach cycling club had a new rider get together event last saturday. i really wanted to get the 7.7fx ready and upgraded before doing group runs because hybrid are lagers to road bikes. can proudly say that my 7.7fx surprised quite a few road guys on looks and performance. the stats in the image are slightly off and i'm unsure why so disregard the top speed and watts. went with the fastest group because i like and kitted the bike out for speed and to just have something unique. our group of 6 with calm conditions held a average 25 to 27 mph. rode to the event casual and home as well since i live on the beach about 1.5mi away. my top speed for the ride was 27.7 mph @ 130 watts with a avg of 18.2 before walking the bike to a local place for lunch. won't lie i was gassed after my first group ride.

by dramatically reducing weight i've gained 4mph to the top speed i can maintain. i know what the bike could do when i took her off the show room floor and to hold 25 to 27 back then was impossible.

for the OP imo get the fx. it will be lighter for the wife. the fx will be faster and just as fun as the DS.

GOOD skinnier tires and an appropriate cassette can make a remarkable difference in acceleration and average speed.

I'm firmly in the lighter and more road bike-like is faster camp, but I owned both an FX 7.2 and a DS 8.3 and found my DS to be faster. I couldn't for the life of me figure out why I would see consistently faster average speed times over the same course on the heavier DS 8.3.

I ended up trading my FX on a Secteur (which was faster than either) and then finally traded my DS on a Roubaix which is the fastest bike I've owned. I found the road bikes to be much more comfortable and efficient than either of the hybrids.

The difference is probably fit. A bike that fits differently will put the rider in a position that allows better or worse power output. A cheap bike that fits well will likely be faster than a 'high quality' bike that does not fit properly.

LBS, Here as Typical, Has a Scale to weigh bikes . walk in and check it out. (If it matters enough)