Welcome guest, is this your first visit? Click the "Create Account" button now to join.

To disable ads, please log-in.

Shop at TeamEstrogen.com for women's cycling apparel.

Results 1 to 15 of 15
  1. #1
    Join Date
    Feb 2011
    Posts
    32

    650C vs 700c gearing

    To disable ads, please log-in.

    I currently have a Terry Tailwind I often find I'm a lot slower than riders around me. I get dropped on rides most of the time. :/
    I feel like I am spinning out of control whenever I shift. Is there a way to change this or is it just me?

    When I went to the velodrome they had a 650c track bike for rent and I often found I was spinning out of control as well - they used the same track gearing as the 700c bikes. I am assuming this is the same reason for me spinning out of control on my road bike. The gearing for 650c wheels and not 700c?

    I've been finding it hard to find advice at bike shops since I have only found shops have 700c. I'd get a 700c if I could touch the ground and there was no toe overlap.

  2. #2
    Join Date
    Jun 2010
    Posts
    6,446
    Which rings are the chain in, front and back, when you spin? Do you shift in the front chain rings at all?

    I can't tell much from your post, but perhaps read this by Sheldon Brown, then get back to us and be more specific with questions?

    Tire size does not affect shifting in any significant way, other than the fact that a smaller wheel have to rotate more times to travel the same distance. I think this is probably a shifting technique issue.

    Can you tell us the exact make, model, and year of the bike so we can look up the groupset? Do you know what brand groupset is on the bike? Maybe shimano? Also what numbers you see on the front chainrings? ARe there two chainrings in front, or three? Also, how many cogs are in the back? Are there any numbers on the back cog/cassette? If so, what are they?
    Last edited by Muirenn; 06-08-2015 at 10:18 AM.
    So long as the wheels are still turning, life is good.

    Battswebb

    Pinarello Quattro~CAADX~ Zurich Lemond
    Specialized Romin Saddles

    Surly Krampus!

  3. #3
    Join Date
    Dec 2005
    Location
    WA State
    Posts
    4,389

    it does affect gearing, but only a little

    Wheel size does make a very small difference, but it's really pretty small. With all other things equal the speed difference between 700's and 650's at the same rpm's is 10ths of a mile per hour. You will have to spin a little faster on 650s than 700s at the exact same gear ratio to maintain the exact same speed, but not by so much that it should be particularly noticeable and definitely not so much that you are spinning wildly - it's probably only around 5rpm difference. You can check it out here: http://velobase.com/Resource_Tools/GearCalc.aspx

    I have both bikes with 650s and 700s. My 650 has standard double road gearing, the same as my 700. I can't say I notice any difference riding the two. The 650 is the heavier of the bikes, so it's actually faster on descents…
    Last edited by Eden; 06-09-2015 at 06:54 AM.
    "Sharing the road means getting along, not getting ahead" - 1994 Washington State Driver's Guide

    visit my flickr stream http://flic.kr/ps/MMu5N

  4. #4
    Join Date
    Jun 2010
    Posts
    6,446
    Quote Originally Posted by Eden View Post
    Wheel size does make a very small difference, but it's really pretty small. With all other things equal the speed difference between 700's and 650's at the same rpm's is 10ths of a mile per hour. You will have to spin a little faster on 650s than 700s at the exact same gear ratio to maintain the exact same speed, but not by so much that it should be particularly noticeable and definitely not so much that you are spinning wildly - it's probably only around 5rpm difference. You can check it out here: http://velobase.com/Resource_Tools/GearCalc.aspx
    I wondered about that, thanks for the link, Eden.
    So long as the wheels are still turning, life is good.

    Battswebb

    Pinarello Quattro~CAADX~ Zurich Lemond
    Specialized Romin Saddles

    Surly Krampus!

  5. #5
    Join Date
    Feb 2011
    Posts
    32
    The Terry Tailwind is from 2011 with the shimano 105 group set. There are two chainrings in the front.
    Little one has 34t and 50t in the big ring. hopefully I didn't look at it incorrectly. 10 cogs in the back. It has 165mm cranks.

    Sometimes I'm spinning in the big chainring when I'm on flats.
    I don't have a bike computer that calculates my cadence either.
    Hopefully these photos help.

    Click image for larger version. 

Name:	unnamed-1.jpg 
Views:	102 
Size:	63.5 KB 
ID:	17639

    Click image for larger version. 

Name:	unnamed-2.jpg 
Views:	93 
Size:	55.0 KB 
ID:	17640

    Click image for larger version. 

Name:	unnamed.jpg 
Views:	112 
Size:	67.1 KB 
ID:	17641

  6. #6
    Join Date
    Feb 2005
    Location
    Concord, MA
    Posts
    13,099
    I've had bikes with both 650 and 700 wheels and there was no noticeable diference in my speed. When you are talking about "spinning," it sounds like this might be more of a gearing issue than what size wheels you have. I am a natural "spinner," in that my cadence is always high, I never stand or mash the pedals, and I tend to use the easiest gear I can, to give me the speed I want. But, you might feel that you need a gear that is in between the ones you have on the rear cog. When this happens, you can feel like one gear is too hard, but the next lowest one has you spinning like crazy. I felt like this when I switched from a triple to a compact double; there's bigger jumps in the gear ratios on a compact. I learned to get used to this by using the harder of the cogs and getting used to that. Four years later, it's not an issue and both my bikes have this kind of gearing. It sounds like your Terry has similar gearing, so you might try experimenting with using slightly different gear combos.
    2015 Trek Silque SSL
    Specialized Oura

    2011 Guru Praemio
    Specialized Oura

  7. #7
    Join Date
    Sep 2007
    Location
    Uncanny Valley
    Posts
    14,645
    I think maybe a cadence sensor might be a good idea, either that or just use a watch or computer with a seconds display, and count your cadence when you're in a safe, flat place and spinning at a cadence that you feel is "out of control." Everyone has a "powerband," a most efficient cadence range, that's different for everyone - but on the other hand, learning to pedal in circles rather than squares, is a neuromuscular skill that can improve with practice. It's one thing if you feel like you're out of control at 130 rpm ... a completely different thing if it's 70. Especially since you're feeling out of control in your big ring on the flats - and on a track bike, which are typically geared pretty tall - that suggests that you're pedaling inefficiently at a rather low cadence.

    Make sure your bike is properly fit - that can make a huge difference - and it's certainly possible that even the 165 mm cranks are too long for you, which is a dilemma since it's very hard to find anything shorter. Me personally, I can't ride anything longer than 165 without causing both knee and Achilles tendon injury, besides it being much harder to spin, and I'm on a 50 cm frame (though that's a little bit large for me, and my tibia/femur ratio means I tend to need shorter cranks than most people with my overall inseam length).

    Try looking up drills and form cues for pedaling efficiency. A couple of easy things to do are just simply visualizing pedaling in circles at a comfortable cadence, try to sense and eliminate any hitches or "angles" in your pedal stroke. Downhill intervals are a great drill - get to the top of the hill without working too hard, then coast down while pedaling in whatever gear allows you to just keep tension on the chain. A cadence sensor would also let you do cadence intervals on the flats - just spin up as high as you can without bouncing for one minute, then rest, then repeat.

    Equipment issues are important, but don't overlook the neuromuscular issues.
    Last edited by OakLeaf; 06-11-2015 at 05:50 AM.
    Speed comes from what you put behind you. - Judi Ketteler

  8. #8
    Join Date
    Jun 2010
    Posts
    6,446
    Okay. The pictures help a lot. The chain is 'crossed,' which it shouldn't be, so I think shifting technique needs to be clarified. (Forgive me if any of this is obvious, but it should help someone, anyway).

    Spinning: spinning is done in the low gears. Generally, that means the chain will be in the little ring in the front.

    Basic drive train setup:

    1. As you sit on the bike, the left-most rings front and back are the lowest gears, also called the 'easy' gears. These are where the highest spinning speeds occur.

    2. The right-most chains, front and back, are the higher gears, or hardest. These require more force. Staying in high gears is known as 'mashing.'

    3. Cross-chaining. This occurs when the chain is on the left side of the drive train up front while on the right side of the drive train in the rear, or vise versa. Cross-chaining can cause damage to your drivetrain, and make it more likely to drop the chain while riding.

    If the front chain is shifted from the large ring to the small ring while the chain in the rear is all the way to the left, you will spin-out.

    4. It's good to mount and dismount with the chain in the low gears (so on the left sides of the cogs front and back), so that the next time you start up, you are in the easy gears, and can shift from there as-needed.

    5. When the chain is in the front small ring (to the left), the chain in the rear should be somewhere between the far left (largest cogs) and middle of the cog.

    6. When the chain is in the large ring in front, the chain in the rear should be between somewhere in the middle, and all the way to the right, or smallest cogs.

    7. You shouldn't use the left shifter unless the chain is somewhere in the middle of the cog in the rear. This prevents cross-chaining and chain-drop. And also encourages you to have the chain in the correct place in the rear whichever chain-ring you are in up front.

    8. Shift from left to right, or right to left, by easing the back chain smoothly along the cogs to the middle, then shifting up front, then continuing in the rear the rest of the way.

    Shifting Shimano:

    1. The left shifter shifts the front rings. Using the small left shifter shifts the chain to the small ring up front. Using the large left shifter shifts the chain to the large chain ring up front.

    2. The right shifter shifts the rear cogs. The small lever on the right shifts the chain to the small cog in the rear. The large right shifter shifts the chain to the large cog in the rear.

    Recap: Left side of the drive train spins in easy gears. Right side mashes in hard gears. Small levers shift to small rings, whether front or rear. Large levers shift to large rings, whether front or rear. Middle of the cog in the rear, whether the chain in front is in the small or large, gives mid gears.


    Avoid cross-chaining: Only use the left shifter (front rings) if the chain in the rear is somewhere in the middle of the cog. You may need to move the small right lever to adjust the rear cog chain position first if you suddenly need to change up front. (For example, you suddenly find yourself going too fast downhill, move small right lever, followed by the large left lever, or you need to speed up to keep from being dropped. Same pattern in revers to ease down from using the hard gears. Ease the large rear lever towards the larger gears until the chain is in the middle, then the small left to put the chain in the small ring up front ).

    Spin while going easy or uphill, but allow that (downshift) to be gradual so you don't spin-out immediately and run out of gas. But don't shift while under too much load or pressure.

    Go to higher gears when you suddenly need to speed up, or while going downhill to control your speed.

    Develop your ability to spin in low gears, so try to have the chain on the left up front, and middle or the somewhere to the left in back. That way, when you do need to speed up, you have the ability to shift and get suddenly much faster.

    All of this means you need to be comfortable looking down at your drivetrain frequently while riding. You may need to practice this skill.
    Last edited by Muirenn; 06-11-2015 at 06:36 AM.
    So long as the wheels are still turning, life is good.

    Battswebb

    Pinarello Quattro~CAADX~ Zurich Lemond
    Specialized Romin Saddles

    Surly Krampus!

  9. #9
    Join Date
    Sep 2007
    Location
    Uncanny Valley
    Posts
    14,645
    I just went back and re-read the OP also, and "if I could touch the ground" is a big red flag.

    If you can touch the ground without leaning your bike over, on a road bike, then your seat height is too low. You'll never be able to pedal efficiently if you're not extending your legs, and even a very low cadence may well feel "out of control" if you're having to hyper-flex your knees and hips on each stroke. You don't want your knees fully extended at the bottom of your pedal stroke, but mostly so. A quick and dirty test is to set your seat at the height where, at the pedal's lowermost point and your leg fully extended but NOT clipped in, your heel just touches the pedal at the spindle center. Then when you move your foot back into pedaling position, there will be a slight bend in your knee. An illustration of some bike fitting basics is here.

    If you've been riding with your seat much lower than that, then don't change it all at once. Small changes make a big difference in your biomechanics, so let your body adjust gradually. Raise your seatpost at most 3-4 mm each ride. Take as many rides as you need at any given seat height to adjust to the difference, before you raise it the next increment. Get comfortable with leaning the bike over when you come to a stop. Turning your handlebars slightly away from the foot you plan to touch down with, will help initiate a lean. While it's good to be able to touch down with either foot, IMO you'll have a smoother learning experience if you make a habit of always putting the same foot down, so you don't experience a moment of indecision. Then once you're completely comfortable and habituated to that foot, then you can start learning to put the other foot down instead.

    Now, if I've misinterpreted what you meant by "touch the ground," then sorry for the misunderstanding ... I know that's the same phrase I use about motorcycle seat height when what I mean is that my leg strength and angle won't support the bike if I lean it over far enough to touch the ground, and/or I won't have enough straight line traction from the rear wheel to get it back moving again ... still it would be extremely unusual for a bicycle frame to fit your upper body properly, yet be so tall that your wheel is at any extreme lean angle when you're at a stop ...
    Last edited by OakLeaf; 06-11-2015 at 05:46 AM.
    Speed comes from what you put behind you. - Judi Ketteler

  10. #10
    Join Date
    Jun 2010
    Posts
    6,446
    There are a lot of 'how to' shifting videos available. Some are easy to follow, some not.

    I like this one.

    Many of these videos just don't show what you need. If you search through, you should be able to find something that works for you.


    If you need a bike fitting to adjust saddle height etc. properly, I'd find someone who seems to know what they are doing, and who is willing to spend some time with you on the trainer coaching you to shift properly.

    ~ 34 x 50 with 10 cogs in the rear is a good range. It's a compact double. Don't see any reason to change it. You might need the drive-train adjusted due to cross-chaining. Chain may be a little loose.

    Also, if you are on a group ride with a large rack on your bike, that will make it harder to keep up.
    Last edited by Muirenn; 06-11-2015 at 06:13 AM.
    So long as the wheels are still turning, life is good.

    Battswebb

    Pinarello Quattro~CAADX~ Zurich Lemond
    Specialized Romin Saddles

    Surly Krampus!

  11. #11
    Join Date
    Feb 2011
    Posts
    32
    i actually got fitted in January 2015 and it has improved a lot since. I definitely feel less fatigue. Got my cleats/pedals adjusted, saddle and saddle height. He said the fitting is guaranteed for a year- maybe I should go back? I do remember him asking me what my cadence was but I couldn't give him a clear answer - I guess I wasn't prepared for that.

    When I'm at a stop on my 650c bike I can touch the ground but I am on my toes. I was saying if I was on a bike with 700c I can't touch the ground even if it had a 42cm frame.

    Oh hahaha, I think the cross chain looks like that because I shifted to count the teeth on the chainring.

    sorry I feel like I'm making this more difficult than it should be.
    Last edited by amyp; 06-11-2015 at 06:21 AM.

  12. #12
    Join Date
    Jun 2010
    Posts
    6,446
    Quote Originally Posted by amyp View Post
    When I'm at a stop on my 650c bike I can touch the ground but I am on my toes. I was saying if I was on a bike with 700c I can't touch the ground even if it had a 42cm frame.
    A smaller bike with too large wheels for its overall design often compensates by being raised higher since the wheels are bigger, so the bottom bracket is higher from the ground. That means the bike would be better with 650c wheels. Trek actually makes small WSD bikes with a geometry that allows 700c wheels. Their R D & D for women's bikes is quite good.

    Cyclocross bikes fit this way on purpose, the bottom brackets are higher in order to clear off-road obstacles.

    Cadence: if you have a seconds counter on your computer, you can count rotations for a minute, and estimate your cadence, it is simply rotations per minute.
    Last edited by Muirenn; 06-11-2015 at 08:07 AM.
    So long as the wheels are still turning, life is good.

    Battswebb

    Pinarello Quattro~CAADX~ Zurich Lemond
    Specialized Romin Saddles

    Surly Krampus!

  13. #13
    Jolt is offline Dodging the potholes...
    Join Date
    May 2007
    Location
    Southern Maine
    Posts
    1,677
    Quote Originally Posted by Muirenn View Post
    Also, if you are on a group ride with a large rack on your bike, that will make it harder to keep up.
    Only if the rack has a bunch of stuff on it...
    2011 Surly LHT
    1995 Trek 830

  14. #14
    Join Date
    Jun 2010
    Posts
    6,446
    Quote Originally Posted by Jolt View Post
    Only if the rack has a bunch of stuff on it...
    An empty rack slows me, at least a little. It also changes handling.
    So long as the wheels are still turning, life is good.

    Battswebb

    Pinarello Quattro~CAADX~ Zurich Lemond
    Specialized Romin Saddles

    Surly Krampus!

  15. #15
    Join Date
    Feb 2005
    Location
    Concord, MA
    Posts
    13,099
    I have a 47 cm Trek Silque with 700 cc wheels. It's perfect. No toe overlap. Ten years ago, I had a Trek 5200 WSD 47 cm with 650 wheels. Both were fine... but I feel no need for 650 wheels now.
    2015 Trek Silque SSL
    Specialized Oura

    2011 Guru Praemio
    Specialized Oura

 

 

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •