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  1. #16
    Join Date
    Nov 2009
    Posts
    12

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    I'm just thinking out loud here...but maybe it'll help. What things affect speed?

    1) overall weight of a bike
    2) rotation mass of the bike
    3) rolling resistance of tires
    4) fit/position
    5) aerodynamics
    6) drivetrain drag
    7) gearing

    Anything else I'm missing? Weight affect your speed on relatively flat routes is negligible...so rule out #1 unless you're route is very hilly. So how about the wheel/tire/tube combo? Does the new bike have a lighter package? Or heavier? What psi are you inflate to? Does this bike have wider or skinnier tires? Does the tire/tube combo yield lower or higher rolling resistance?

    How is the fit on the Ruby compared to the 1.2? More relaxed? More aggressive? Are the seat heights the same? How about crankarm lengths? Crankarm length won't make a big difference...and in the cycling world, 1.5mph (from 15.5 down to 14) is GARGANTUAN!!!!!!!!!! But you definitely don't want to be turning a crank that's too long for you as that could lead to knee problems.

    Regarding aerodynamics...they're both roadbikes...so he difference is negligible. Unless the position on the ruby is very very relaxed compared to the 1.2...in which case, aerodynamics of your fit could play a very very non-trivial role.

    Drivetrain drag? Double check those brakes to make sure they're not rubbing. Wheels should turn easily and freely...bearings should be well greased. Same with bottom bracket. And the chain. Sometimes, on a new bike, it make take several rides for everything to loosen up.

    Gearing...I think might be playing a small role. You went from your Trek with a 50-39-30 crank and 11-26 cassette to the Ruby with a compact 50-36 with a 12-27 cassette. The highest gear ratio on the Trek is the 50-11 combo (8.9)...highest on the Specialized is the 50-12 combo (8.2). So all things being equal (tires, tubes, pressure, rotational mass, your power and cadence,ect)...if you were able to maintain a 60RPM cadence, you'd be going 21.3mph on the Trek and 19.5mph on the Specialized. A difference of 1.8mph...similar to the speed disparity you've been noticing.

    So if it's gearing...how can you change it? Get a 11-28 cassette for the Ruby. That'll give you a high end ratio of 8.9 (just like your Trek)...and a low end of 2.5 (pretty close to the 2.3 you can achieve with the Trek) for the hills.

  2. #17
    Join Date
    Aug 2009
    Posts
    321

    Cool

    So how about the wheel/tire/tube combo? Does the new bike have a lighter package? Or heavier? What psi are you inflate to? Does this bike have wider or skinnier tires? Does the tire/tube combo yield lower or higher rolling resistance? The new bikes' setup is lighter than the Trek, the tires are the same.

    How is the fit on the Ruby compared to the 1.2? More relaxed? More aggressive? Are the seat heights the same? How about crankarm lengths? The Ruby has a more aggressive position, crankarms are the same length, I think the seat height may be a little different but I am raising it a bit at a time until it feels right.

    Double check those brakes to make sure they're not rubbing. Wheels should turn easily and freely...bearings should be well greased. Same with bottom bracket. And the chain. Sometimes, on a new bike, it make take several rides for everything to loosen up. Just loosened the brakes and will grease up the chain this afternoon.

    Gearing...I think might be playing a small role. You went from your Trek with a 50-39-30 crank and 11-26 cassette to the Ruby with a compact 50-36 with a 12-27 cassette. The highest gear ratio on the Trek is the 50-11 combo (8.9)...highest on the Specialized is the 50-12 combo (8.2). So all things being equal (tires, tubes, pressure, rotational mass, your power and cadence,ect)...if you were able to maintain a 60RPM cadence, you'd be going 21.3mph on the Trek and 19.5mph on the Specialized. A difference of 1.8mph...similar to the speed disparity you've been noticing.

    So if it's gearing...how can you change it? Get a 11-28 cassette for the Ruby. That'll give you a high end ratio of 8.9 (just like your Trek)...and a low end of 2.5 (pretty close to the 2.3 you can achieve with the Trek) for the hills. This makes a lot of sense to me, the way you have explained it. I wonder how much a new cassette would run me?

    Thank you for the detailed reply!

  3. #18
    Join Date
    Aug 2009
    Posts
    321
    Teamtrinity, I called my LBS and they are going to put an 11-28 on it tonight or tomorrow. THANK YOU.

  4. #19
    Join Date
    Sep 2009
    Location
    Renton, Wa
    Posts
    432
    I had the same problem on my new Orbea on one of my first rides and it was the brakes rubbing. Once I fixed that, I was flying! I'm so glad you guys are talking about this, because I had also been wondering if the flex could cause them to rub inadvertently while I'm riding, because off and on during rides sometimes it still seems like I'm pushing harder than I should, but when I stop to look at the brakes, they look fine! I think I'll adjust the cables and see if that helps overall.

    -Jessica
    "Namaste, B*tches!"

  5. #20
    Join Date
    Oct 2008
    Posts
    355
    I'm just thinking out loud here...but maybe it'll help. What things affect speed?

    1) overall weight of a bike
    2) rotation mass of the bike
    3) rolling resistance of tires
    4) fit/position
    5) aerodynamics
    6) drivetrain drag
    7) gearing
    overall weight of a bike, assuming you aren't going from a 15 pounder to a dutch cargo bike, should have very little effect on "speed." Rotating weight plays a much larger role.

    I am also having a hard time buying any measurable effect due to rolling resistance of tires, assuming tires are reasonably similar from bike to bike.

    What is "drivetrain drag?"

    Why would the gearing matter? If you are riding the same gear on both bikes, it doesn't matter what your lowest gear or highest gear is...unless you are letting the gears choose you instead of vice versa? Bikes don't have automatic transmissions--you choose the gears. The only time it would result in "slowing" is if you are spinning out your biggest gear...and I kinda doubt that is what is happening.

    My hunch is that any measurable "slowing" has to do with whatever changes have occurred in your position, particularly all the variables involving your saddle position. That is where your power comes from. Any change in saddle height, saddle fore/aft, or seat tube angle can have an effect on your power and ability to turn over the gears.

  6. #21
    Join Date
    Nov 2009
    Posts
    12
    Quote Originally Posted by greenbeanvw View Post
    Teamtrinity, I called my LBS and they are going to put an 11-28 on it tonight or tomorrow. THANK YOU.
    My post above with ratios was mostly for illustrative purposes to show how your gearing choices can affect speed. HOWEVER...keep this in mind...you may not see a jump up in average speed of 1.8mph. It really depends on your route...and what gear you typically find yourself riding in.

    Your 12-27 was probably: 12-13-14-15-16-17-19-21-24-27
    Your 11-26 was probably: 11-12-13-14-15-17-19-21-23-26

    See how on the smaller end they both have 12-13-14-15-17? If you spent a lot of time in the 11 or 15 on the Trek, that might account for the slower speed on the Specialized because you would have had 12 as your smallest...and you may have been using the 16 instead of the 15.

    And your 11-28 will probably be: 11-12-13-14-15-17-19-21-24-28

    The first 8 gears will be the same as your Trek...and it'll also have 8 gears in common with your 12-27 currently on the Specialized. Again...you may see a bump up in average speed...but it'll only a a significant bump up in speed if you tend to use the smallest gear alot.

    In any case....good luck!!!!

  7. #22
    Join Date
    Aug 2009
    Posts
    321
    I did use the small gear quite a bit on my Trek for the hills in my area and I feel as if I am missing my "middle range gear" on the Specialized (I am guessing this is the 16)?

    How many mm's of space do you all keep between your wheel and the brake pad? Mine were so close initially, that I really had to look to make sure they weren't rubbing. I just loosened them to the point that I can see the space between the two, but the brakes still do their job.

    Would you all wait a few weeks and get a fit before you switched out the cassette?

  8. #23
    Join Date
    Jun 2009
    Posts
    199
    Quote Originally Posted by greenbeanvw View Post
    Teamtrinity, I called my LBS and they are going to put an 11-28 on it tonight or tomorrow. THANK YOU.
    I recently put 11-28 on my Trek 5.2 (compact). I had similar issues moving from my Specialized TriCross Triple (with an 11x34 cassette!). The 11-28 has helped quite a bit. I hope you have similar experience to me.

    I'd also recommend getting fitted professionally. My fit changes have made riding SO much more enjoyable. No more sore shoulders!

  9. #24
    Join Date
    Nov 2009
    Posts
    12
    Quote Originally Posted by greenbeanvw View Post
    I did use the small gear quite a bit on my Trek for the hills in my area and I feel as if I am missing my "middle range gear" on the Specialized (I am guessing this is the 16)?

    How many mm's of space do you all keep between your wheel and the brake pad? Mine were so close initially, that I really had to look to make sure they weren't rubbing. I just loosened them to the point that I can see the space between the two, but the brakes still do their job.

    Would you all wait a few weeks and get a fit before you switched out the cassette?
    Absolutely...get the fit done first. Then ride the snot out of the bike for 2-3 weeks. If it still feels slow...then think about changing gears.

    As far as the Specialized feeling like it's missing a middle range gear...it's possible. I'm just guessing on the exact configuration of your cassettes. The smallest gear in the cassette probably wouldn't be used for climbing though. Your climbing gear would be the small chainring up front, with the largest cog on the cassette in the back.

    As far as the brakes...mine are set pretty close. I never measure...I just guesstimate. Close...but not close enough where they rub on the road.

  10. #25
    Join Date
    Aug 2008
    Location
    South Central PA
    Posts
    190
    Aluminum has a much stiffer feel than carbon, in my experience. Some carbon bikes feel sluggish to me. I have a carbon bike now and love it, but in trying bikes during my search there were some very expensive carbon bikes that felt too soft for me and my riding style.
    "No hour of life is wasted that is spent in the saddle" -Winston Churchill

 

 

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