Disadvantages of 650c wheels?

Discussion in 'Cycling Equipment' started by Karlo, Feb 28, 2004.

  1. Karlo

    Karlo New Member

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    Hi,
    One of my friends is convinced that her Trek women's specific bike is somehow inferior to others because it has 650c wheels. Are 650c wheels bad in any way? I imagine that they help smaller people fit smaller bikes, but are there any disadvantages?

    She is about 5'6" or 168 cm, should she look for a new bike with 700c wheels?

    Any thoughts?
     
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  2. fushman

    fushman New Member

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    you cant swap out her wheel set when she takes the day off and you dont?
     
  3. boudreaux

    boudreaux New Member

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    She is probablyl getting a barge load of hooey from people who really know nothing about the issue,but can't help spouting off and regurgitating alot of drivel. Unless she has short legs, at 5'6" she may not need a bike with 650 wheels. But since she has got it and it fits and there are no other issues, it's certainly not worth dumping over 650 wheels. If a person gets better fit on a bike with 650 wheels it far outweighs any claimed disadvantages. There are alot of 'small ' bikes built with 700 c wheels but they still end up with a long TT and have compromised geometry in order get the smaller nominal frame size.. There will be a lesser selection of aftermarket wheels and forks. Tire sizes and variety are somewhat more limited. I'd have some extras tires and tubes on hand and alwys carry a spare tube, just in case. Another possible disadvantage is not high enough gearing caused by the smaller diameter wheels. If that is a problem, a smaller rear cog cassette and a bigger chainring is the fix.
     
  4. capwater

    capwater New Member

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    I'm kinda on the fence with the whole "women's specific" concept. I believe one of the aspects is a shorter top tube to help a women's shorter reach. At 5'6" (the same height as my wife) she really could have no problem with a 700c bike, possibly a compact geometry. I have a 105 group 650 tri bike that my wife rides some times, although she prefers a full size 700 most of the time. You will be able to find tires and tubes online from outfits like performancebike.com and coloradocyclist.com, but as previously stated your selection will be limited to usually only about 2 tire choices (and they ain't cheap either). She already has the bike and it seems to fit well so go out and ride. If and when the time comes to upgrade then you could revisit the question. Size (ie; the number like 52cm, 54cm etc) will vary widely between mfgrs. I personally ride a Klein with a longer top tube wich is more comfortable than the "standard". Have fun!
     
  5. pudster

    pudster New Member

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    A 650c bike is really at no disadvantage for small people except for a little less of a high gear (maybe 12 gear inches) and a little less comfort from smaller wheels on rough roads. A700c bike can be built with a 50 cm top tube and still be made into an effective frame. Anything shorter and it will be a problem. There is no more standover clearance gains from a 650c bike. If you have good wheels a 650c wheel is actually more aero than a good 700c wheel because of smaller frontal area.
     
  6. boudreaux

    boudreaux New Member

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    Name one, then define 'effective'.
     
  7. pudster

    pudster New Member

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    I am sorry I miss spoke I meant a 52cm TT, a 50cm can also be made but there will be problems such as some toe clip overlap.
     
  8. boudreaux

    boudreaux New Member

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    A custom builder cannnot do anything with 700c wheels that a major brand maker cannot do, or has not already done.There is no Black Art involved. Everyone likes to play the 'custom' card on this one,but it does not fly.
     
  9. pudster

    pudster New Member

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    But are they willing to? They only build for the masses.
     
  10. boudreaux

    boudreaux New Member

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    Lemond is just one that does it or has done it in both standard and WSD with 700c wheels. I'd go for a WSD with 650c rather than the design comprimises built into 700c in that sze range. It takes alot of fork rake and extremely slack head angle among other things. 650 is just a smarter way to do it if you want a 50cm TT. Custom cannot get around that just due to the physical size of the bigger wheel.
     
  11. pudster

    pudster New Member

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    I would sure agree with you on that. I did not mean to say that 700c with a 50cm TT is the way to go. I need to learn to get my ideas in writing better!
     
  12. tafi

    tafi Member

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    Smaller diameter wheels suffer from slightly greater rolling resistance at the tyre road interface since imperfections in the road (and there are many of these little bumps - pea gravel road included) are larger compared to the wheel size than for a 700c wheel.
    The only reason someone would choose 650c over 700c would be for a course with a lot of rapid accelerations (650c has lower rotational inertia). Once speed gets higher and more constant 700c wheels are better.
     
  13. boudreaux

    boudreaux New Member

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    That is so insignificant as to not even be worth mentioning(AKA, alot of hoey). Correct fit and frame geometry that has not been compromised to get it rate #1.
     
  14. Geonz

    Geonz New Member

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    She's got the 650, right?

    No need to feel insecure about it. Whatever bike she's on, *somebody* or a group of people will think there's something fundamentally inferior about it.

    If she wants a new bike, she can use it as an excuse, but if she likes the one she's got, she should just ride it :)
     
  15. Karlo

    Karlo New Member

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    Thanks a lot for all of the replies!

    I think I understand all of the logic flying around here, but as several pointed out, she already has the 650c bike that fits her. No huge reason to switch. But then again maybe if she believes that a 700c bike is the panacea for all her riding problems, it might just be (the psychological edge).

    Anyway, thanks for all of the advice.
     
  16. drewski

    drewski New Member

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    ok, should we now discuss her "riding problems" to make sure she doesn't spend $$ unnecessarily? :D
     
  17. EvilDog

    EvilDog New Member

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    Tell your wife that there is too much to gain by sticking with a 650c bike. First of all you take her height which is 5'6" or 66". Take the average male rider whose height is 5'11" or 71". This represents a size difference of 7.6%. Now take the wheel diameter of 650c vs 700c. The difference between these two sizes is 7.7%. In other words, the differences are virtually identical when compared side by side.

    If one can say that a 5'11" man riding a bike with 700c wheels is considered a perfect fit, then likewise a 5'6" woman should reasonably want to have a 650c wheel to achieve the same perfect fit.

    There are other reasons why she should stay with the smaller wheelsize. As mentioned, they have a smaller frontal area which reduces the amount of aerodynamic drag that she will experience while riding. Then there is the fact that a 650c wheel will spin up more quickly which allows for faster accelleration. This is a very important factor, even when one is maintaining a steady speed over flat terrain. Then there is the obvious weight saving factor in that 650c wheels are lighter than equivilant 700c size ones, no matter how you slice it!

    The reality of cycling is that when you are pedaling your speed is NOT constant. In fact, if you analyze it literally inch by inch as you travel along, you will find that each pedal stroke begins with a micro accelleration because during the transition period between the end of one leg's pedal stroke and the beginning of the other leg's stroke, the bike has decellerated just a fraction of a bit. This results in each pedal stroke having to put out just a little extra power just to make up for this loss in order to maintain a constant speed. This is true no matter how well you are able to "pedal in circles".

    Taking this a step further, imagine that you are really great at pedaling in circles and your speed loss represents just .1% of extra power needed to be inputted as extra to compensate for this by using 700c wheels as opposed to 650c wheels. This means that after a 40km ride you will be 40 meters behind as a result than if you had been using 650c wheels. While this might not seem like much, it does represent a time difference of about 10 seconds assuming an average speed of about 18mph. This assumes all other factors being equal and you are riding on a totally flat road course.

    In reality the difference can be much greater when you factor in all the advantages, lighter weight for the 650c wheel, less aero drag, and speedier accellerations. Your time difference will more likely result in a minute or more in savings depending on how hilly your riding course.

    As for myself, I am a male 5'9" and normally ride a bike with a 700c wheelset on it. I am, however, planning on building a mountain ascending bike for use in uphill time trials. It is because the 650c wheel is faster in recovering from these micro-decellerations (which are much more pronounced when going up steep grades than on the flats) I am going to be using 650c wheels for this specific bike. Doing the math, I figure to save somthing like 15 seconds or more for each mile of 6% grade that I climb, this savings will increase as the grade increases. Since most of these types of time trials are anywhere from 5 - 9 miles in length, this adds up to a huge time saving over all.

    In summary, tell your wife that she should look at logic and reasoning before considering making a switch and not to listen to the uneducated rabble speaking from stupidity.
     
  18. boudreaux

    boudreaux New Member

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    The first sentence was pretty lucid. After that the BS sorta took over. But it got back on track in the last sentence.
     
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