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Old 01-14-08, 12:37 PM   #1
sp00ki
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Good gearing for rollers (high cadence)

(from this topic)

I'm buying a set of rollers next month, and will be purchasing an ultra cheap "track bike" ($75) for sole use with the rollers. I already have a trainer setup for doing resistance and sprint intervals, but wanted to use rollers specifically for improving high cadence form/aerobic condition on alternate days.
I'm thinking a very agile gearing will force me to do high rpm, and eventually improve my form on descents/all out sprints.
What gearing is too "agile" for rollers? I understand that part of the physics behind balancing on rollers is spinning your wheel, so i don't want it to be so low that the rollers are rendered useless, but i don't want it to be too high as to offer any resistance. I don't have experience on rollers w/a low gear ratio, so i'm kinda clueless as to how much the lower ratio will inhibit effective rolling. My TT bike is currently in pieces, so i'm thinking a good recommendation is my best bet to avoid swapping out too many chains/chainrings (time/money).

Anyone with experience have a suggestion?
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Old 01-14-08, 02:46 PM   #2
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If pedal revs and wheel revs (to keep you upright) is what you want without any load then gearing that will give you anything from about 65" to 76" will be fine. I think the gearing depends more on what chainring the "cheap" bike will come with than anything else.

It also depends on the rollers too and their drag, or lack of. Small diameter rollers have some drag due to tire friction and roller speed and big diameter rollers, almost nothing. You need a bit of drag to pedal against so that you can keep some pedaling form. If you don't agree with this then just think of a bike with no chain (and held up in a stand). That would be awful for trying to pedal with any kind of form.

If I was in your position I'd go with 72" - that's 48/16.

I've ridden rollers for 46 years so ask away!

Last edited by Mike T.; 01-14-08 at 02:55 PM.
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Old 01-14-08, 03:09 PM   #3
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Thanks!
Here's me picking your brain:

My main purpose for adding rollers to my training is to improve better form at higher cadences (i've never been graceful @ higher rpms). My logic was to use a lower gearing (for instance, 42/17) which would "force" me to keep a higher rpm (lest i fall over), which would in turn "teach" me better form at said rpm (which i'm assuming would come naturally after repeated sessions).
Does this make sense?
Since i already use my trainer for resistance and interval training, i figured this would be a great way to get something beneficial on days i'm not on the trainer or the road.

Does this idea make sense?
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Old 01-14-08, 03:43 PM   #4
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High cadence with no resistance is quite different for your legs from high cadence with moderate resistance. When you're actually racing, you have to deal with high cadence with resistance. Realistically you should be able to do 145-160 rpm with about a 46x15 or so (82.8 inch gear). Going much lower actually can produce some counterproductive behaviors, such as allowing the fixed gear to swing your opposing foot through a broader range without applying pressure, or promoting an exaggerated circular pedal stroke that no one can maintain under actual racing conditions. Most folks I know who race track do winter cadence work on 4.5 inch rollers at about an 81 inch or so gear.
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Old 01-14-08, 05:28 PM   #5
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Quote:
Originally Posted by sp00ki View Post
Thanks!
Here's me picking your brain:

My main purpose for adding rollers to my training is to improve better form at higher cadences (i've never been graceful @ higher rpms). My logic was to use a lower gearing (for instance, 42/17) which would "force" me to keep a higher rpm (lest i fall over), which would in turn "teach" me better form at said rpm (which i'm assuming would come naturally after repeated sessions).
Does this make sense?
Since i already use my trainer for resistance and interval training, i figured this would be a great way to get something beneficial on days i'm not on the trainer or the road.

Does this idea make sense?
Yeah sure it makes sense but as I said and 11.4 said, there has to be some resistance.

Find a gear that gives you something at the revs you want to rev at. For me that's about 120 but I'll be 60 on Wednesday and nothing is as fast as it used to be. Smooth is your goal. Those who aren't smooth bounce up & down on the saddle while pedaling in squares.

You have to rev until you start to bounce and then relax and try to concentrate on making small circles with your feet. Forget any "pulling up" bull**** as it can't be done. At the very best you can concentrate on "pulling back" with the foot as in scraping dogcrap off the shoes.

Last edited by Mike T.; 01-20-08 at 06:36 AM.
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Old 01-15-08, 12:06 AM   #6
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Go to Kreitler's web site. They have a chart for their rollers showing watts vs speed vs roller diameter LINK. If you know what wattage you want, look up the speed for the roller diameter and gear up accordingly. You can fine tune it a bit with your tire inflation pressure. Higher pressure requires lower watts for the same speed.

I suspect other manufacturer's rollers of similar diameter would show a very similar chart.
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Old 01-15-08, 06:42 PM   #7
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Quote:
Originally Posted by Mike T. View Post

If I was in your position I'd go with 72" - that's 48/16.
48x16 is 81".....and 81" is a great gear for rollers.
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Old 01-16-08, 05:26 AM   #8
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48x16 is 81".....and 81" is a great gear for rollers.
Ahhh yes I meant "18". Thanks. 16 was a typo for sure.
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Old 01-16-08, 01:56 PM   #9
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Originally Posted by Giro View Post
Go to Kreitler's web site. They have a chart for their rollers showing watts vs speed vs roller diameter LINK. If you know what wattage you want, look up the speed for the roller diameter and gear up accordingly. You can fine tune it a bit with your tire inflation pressure. Higher pressure requires lower watts for the same speed.

I suspect other manufacturer's rollers of similar diameter would show a very similar chart.
Those charts are notoriously inaccurate. Tire pressure, rider weight, temperature, etc. etc. all contribute hugely. Those numbers can be 30-40% off from what a calibrated SRM will show.
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Old 01-17-08, 08:30 PM   #10
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For spinning, large dia rollers, high pressure wider tires

Quote:
Originally Posted by 11.4 View Post
Those charts are notoriously inaccurate. Tire pressure, rider weight, temperature, etc. etc. all contribute hugely. Those numbers can be 30-40% off from what a calibrated SRM will show.
Yes, this is definitely the case since tire deformation is the major influence on power requirements to cycle on rollers. I was reminded just last night when I had to pump my tires back up before I could stay on my rollers for any length of time.

What the chart illustrates is that if the original poster is mainly interested in spinning, he should get large diameter rollers because these have the lowest power requirements. Other things he can do to minimize the power requirements are pump the tires up to the maximum and use relatively wide tires (and I suspect hard/thick tires) since these have a wider contact patch and deform less. Weighing less will also help.

For further details, see Reiser R 2nd, Watt J, Peterson M. Cycling on rollers: influence of tyre pressure and cross section on power requirements. Sports Biomech. 2003 Jul;2(2):237-49. Abstract at LINK.
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