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-   -   Bobbing during high rpm's (http://www.bikeforums.net/track-cycling-velodrome-racing-training-area/576745-bobbing-during-high-rpms.html)

Yo! 08-21-09 10:18 AM

Bobbing during high rpm's
 
Hey all,

I've been riding fixed a while now in an urban environment, but entering the realm of track cycling. I currently ride a 53cm Panasonic track and I am 5'9 running 77.8" (49/17).

When I'm holding a very fast cadence (nearly spinning out), I find myself bobbing a lot. Is there anything I can do to adjust my form, or possibly an adjustment to my bike that will alleviate this problem? I feel like the bobbing is really killing the smoothness of my cadence.

Thanks again for any suggestions.

queerpunk 08-21-09 10:20 AM

Practice at high cadences. Relax your upper body. Ride rollers. Sometimes bobbing is caused by a slightly too-high saddle.

trelhak 08-21-09 12:31 PM

You bounce a lot on the saddle if you're too low too, or if your pedal strokes are uneven. When you get to the track, speak to some of the coaches and they'll help you fine-tune both your equipment and your form.

Yo! 08-21-09 12:35 PM

I feel like this may be a scenario where my saddle is too low....thanks for the suggestions guys; I'll get a coach to check out my form at the superdrome.

octopus magic 08-21-09 01:16 PM

Not only will you stop bobbing, but you'll get faster with a higher saddle.

carpediemracing 08-21-09 05:41 PM

I am primarily a road rider. I also tend to push big gears, rolling at 80-90 rpm much of the time. My pedal style was not conducive towards track racing, and I spent all year figuring out what I need to do.

I found that lowering my saddle let me spin faster. I have tight hamstrings so that may explain some of it, but in general I found that lower saddle heights buy me more rpms.

The best track rider I've watched recently is Kurt Wegmann (of CycleLoft). He has a pretty low position and uses very low gears relative to his peers (and to me too, but he is so much better than me that I don't consider him a peer). He pounds on us using tiny gears, 86" typically, even in the Keirin.

I had a problem bouncing a bit, and when I mentioned this to a veteran track racer, he suggested I lower my saddle a bit. It helped a lot.

I have a fixed gear spin bike (Schwinn DX-900), and I am fastest on it when I slam the saddle down. I'm not fast compared to "real" trackies, but I've managed to break 280 rpm on it with low resistance. With the saddle closer to my normal height, I am pressed to break 240 rpm.

On my track bike I've focused on trying to increase my cadence since A - I can't spin lower gears like everyone else (86 or 88" gear, I use a 90"), and B - I top out at 33-34 mph (125-130 rpm). I'm convinced that I can go faster since I can hold 35+ mph in a leadout on the road.

I found that if I overspin, i.e. go really fast, then go back to a "normal" cadence, the normal cadence feels slow and smooth. Kind of like going from a 65 zone to a 55 zone in your car, it feels so slow to go 10 mph slower.

Since my races typically put me at 100-110 rpm (26-28 mph) and my sprint is 130 rpm at the most, I figure I should work on going at least 10 rpm faster. Therefore I want to be comfortable at 120 rpm. I use rollers since they have low resistance and penalize you for being rough. I overspin up to 160 rpm, can hold 150 rpm for a while, and can roll at 120 rpm for a while.

When overspinning, I'll do whatever it takes to stay on the rollers. I usually tense my core substantially, get pretty rigid with my arms, etc. Then when I slow, I automatically relax. My goal is to relax more and more of my body in the overspin bits.

A few random tips:
- think "spin faster" not "pedal harder"
- focus on circles, not pulling back or pulling over the top. Circles gets you going good.
- a trainer doesn't help as much as rollers because it doesn't punish you for being rough.
- use a huge fan or two. I use a standard 24"? pedestal fan and a powerful 20-24" commercial strength floor fan. The latter actually takes time to spin up, and it can hold back almost an inch of water in a flooded basement (yeah, I used it to keep part of the floor dry when my previous house's basement got flooded).
- start by holding the tops of the bars. As you get faster and smoother, work your way down.
- since rollers don't develop strength, I'll complement my rollers work with power work on a trainer.

I haven't focused on spinning with such specific goals until this summer at the track, when I had the unpleasant realization that my pedal stroke sucks. After that realization, actually at the beginning of August, I decided to focus on improving it. I worked on my pedal stroke for 1 day at a training crit, did much better at the track the following night (won Keirin and raced well in the other races), then did 3 days of focused pedal work. The next ride was a training crit, and for the first time this year I didn't get dropped. I felt that even the short week of pedal drills really helped smooth me out.

Unfortunately I fell really hard with 1/2 lap to go in that race, and I couldn't go to the track the next day and defend my Keirin win from the prior week. So all my work kind of went away. But I plan on doing more of this kind of work as soon as I can ride again, and I plan on spending a good amount of time on the fixed gear on rollers over the winter. I hope to ratchet up my track racing next year.

cdr

Yo! 08-21-09 06:24 PM

^ Man, that was very helpful.

Thank you for taking the time to explain it so thoroughly!

Velodad 08-22-09 10:35 AM

+1 to what CDR says.
Also, unless you are a young junior (10-13years old) I would suggest you bump up your gear for the track. Putting a 16 on will give you an 82 and a 15 will give you an 88 with your 49 up front. Depending on your strength, you should be able to spin these gears.
This will give you more speed before you spin out. You didn't say at what rpm you spin out at. It's a different number for different riders. Roadies tend to spin out sooner that track riders. Roadies will tell me they were spinning out xx gear at yy mph and I think, "You should have been going faster than that". Then I remember "roadie".
Roadies think 130rpm is spinning out. On the track the race pace may keep you at 140rpm then you need to sprint at 160+. Remember, you can't change gears in the race. If you ride a bigger gear to compensate for lack of leg speed, you wont be able to react to accelerations as quickly as everyone else.

When riding remember, as you spin faster you should move forward on the saddle (AKA riding the rivet) and bring your knees close to the top tube.

Have fun!

Brian Ratliff 08-22-09 07:11 PM

A good way of getting a smooth spin is to train on rollers. You don't have to practice at insane RPMs at first; even with just regular spinning, the rollers will punish people with a choppy pedal stroke. Getting the choppiness out of your pedal stroke at normal rpms (100) will allow you attain RPMs over 150.

Also, I don't know what length crankarms you are using, but 165mm is pretty common on the track, and the shorter crankarms really help with the spinning. It's fairly common for road fixie setups to have 170 or 172.5mm crankarms.

coolkid_cody 08-22-09 10:39 PM

you could simply buy a few new cogs. maybe a 20 and a 22t. Since your fixie is what you will be riding most and I assume is what you ride every day, it would be best to change the gearing up on that if you don't have rollers. start out with the 20 tooth and just ride. You will spin out on flats pretty quickly but you will eventually get comfortable with it. Don't avoid hills and tell yourself not to use your brake. after a couple weeks when you feel more comportable change the cog to the 22t.

My first fixed gear was at 88 GI so I didnt know what spinning out was untill I got my Steamroller. Stock is 66 GI. I could barely ride the thing on flats without spinning out and slaming on my brake, but I used to it after a couple weeks. Whe I started to spin out I automatically moved forward a bit and just barely got out of the sadle. Since I was hopping in the seat like you getting out of the saddle a tad bit helped after doing this for a couple weeks, I was able to sit on the saddle without hopping up and down. This may help you....
I put on a 22t for a hill climb time trial and I spun out on the flats with this until I got used to it. Again dont whimp out and use the break keep on spinning. on flats I can spin the 22 tooth at 210 RPM with my saddle in the normal position and am not sure about hills.

I have a question though, when I go down hills I spin so fast that my front wheel (fork and stering as a whole) starts wobling, if I hold onto my bars tightly the wobling is wose so I just go loose in my arms, but there is still movement. What should I do to correct this? would lowering the seat a bit help this problem as well?

Yo! 08-24-09 09:41 AM

Well I think I may take your advice on swapping the rear cogs. I like my 49/17 for street, and I would call my self a strong rider, so dropping to a 15 or 16 would be acceptable.

Coolkid, I understand what you're saying about going taller on the rear cog, but do you think that it would be more valuable to train with big gears for resistance and speed or to spin out quicker so that I'm creating a scenario where I'm pumping out low speed high rpm's?

Part of the reason I like my setup is that it greatly increases my strength and endurance, especially among my peers who are all riding less gear inches.

I think the biggest thing I can do is get more facetime with the rollers.

coolkid_cody 08-24-09 01:26 PM

Well if you prefer rollers go for it, but changing out the cogs is very inexpensive and once you can ride with the 22t comfortably without spinning out and hopping in the seat you could go back to your preffered street gear and you can acheive the resistance aspect of it and get up to higher speeds than before without spinning out or hopping. I didnt mean stick with just the 22t, alternate your gear every week or couple days even. As for me I stick with my 47 X 22, I work on my spin on flats and down hills and strength on the uphills. Since I live in Colorado Springs there are a lot of great hills to tackle. 66 gear inches is even a bit taller than some of my friends who I ride with on the hills. So I prefer it this way. But since you live in a relativly flat place maybe alternating your cogs would work for you, or go with rollers.

MGtrack 08-29-09 06:27 PM

Check the saddle height as advised, also check the fore/aft position of the saddle. Sprinters like to spin fast and usually come forward on the saddle at high rpms.


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