Bouncing in the saddle
 

We're a fairly new team and have a question for the group. When we increase our cadence, I feel like I'm bouncing up and down in my stoker's saddle (a vertical bounce). So we slow the cadence down and it goes away. Any suggestions to diagnose and correct what's going on? We've tried two saddles and it went away on the one I didn't like (smaller, harder, etc.) We have the other saddle back on and tilted up at the front slightly - which seems to help a little, but not completely. The bike has a suspension seat post for me too. I enjoy reading everyone's comments on this - it's good to glean from everyone's experiences and not have to reinvent the wheel, so to speak.

Thanks - Shelly

Your saddle's most likely a bit too low.

Was the saddle height adjusted with your full weight on it, or was it otherwise adjusted to take suspension sag into account?

Regardless, I would experiment by raising your saddle just a few millimeters at a time to see if you can find the sweet spot where the ride height feels comfortable and you're not bouncing at the higher cadence.

My stoker has the same problem. We've been advised to slow our cadence to around 85 rpm to avoid this issue. However, this cadence makes me work a lot harder than if I were at 100 rpm. :p

Is raising the saddle the only solution? My stoker uses a Thudbuster ST as a seatpost, and I believe that the elastomer is the cause of the bouncing.

Bouncing is a classic symptom of having a saddle that's a bit too low. Having a saddle that's too low and that has a suspension seat post simply exacerbates the bouncing.

The problem is, a suspension seat post can create the bouncing problem if the saddle's height isn't adjusted to compensate for the amount of suspension travel that's used when the stoker's weight is put on the saddle when they're riding. You can minimize the amount of natural suspension sag by using either more preloading on some types of suspension posts or a stiffer elastomer insert on the parallelogram types.

Regardless, the best way to set a stoker's saddle height if they're using a suspension seat post is to set the tandem up on a stationary wind trainer so that they can put their full weight on the bike and ride for a bit before checking to see if they're bouncing (too low) or rocking their hips (too high). If they have a single road bike with a comfortable fit you can simply check the pedal axle to seat rail distance -- assuming they're using the same brand/model of saddle after they've put some time on the wind trainer and gotten the seat post to settle in to where it falls when they're riding.

Suggest removing the suspension seatpost and see what happens . . .
Also, shift down one more gear on the cassette/cog.
Pedal on TWOgether!
Rudy andKay/zonatandem

Debbie lasted 14 miles on our first tandem's Tamer shockpost before she said, "that's not going to work".

Thankfully, our roads are in pretty good shape so... knock on wood ...shockpost free for more than 11 years now.

Occasionally on my cruiser bike, I'll find myself pedaling at just the right rhythm to start a bounce in the tires or seat- usually, just stop pedaling for a half turn does it, gets things out of sync where it doesn't do it.

I also agree the bounce is definitely a seat height issue. I suspect the suspension is the root cause (low or too soft). I would try a solid stem, get it set right and prove to yourself that you can do the high cadence with no bounce. From there play with height on the suspention post height and stiffness...good luck. FWIW my wife does not use a suspension post on our C'dale ...she just got use to riding without one and all is good.

Bill J.

Tweaking saddle height just a millimeter or two can be enough to at least minimize if not eliminate the bouncing. Also, the more time you spend spinning at a higher cadence, the more you learn to smooth out your pedal stroke.

Pulling up on the back stroke of the pedal circle minimizes/eliminates the bobbing on the seat.

I find that taking the seat off and sitting right on the post stops the bouncing..

We have a different problem with bouncing. Ruth is getting airborne when we attack a technical descent where bump dodging isn't an option..

I said I would get her a seatbelt ;) j/k!

+1 on seat height,and eliminating the suspension post.

Additionally, working on form can help. Doing fast pedal drills will help your pedaling stroke. They're done at 120 rpm in a light gear. Start doing sets of 5 for 3 inutes each. Work up to 10 minutes.

If you're not used to pedaling at a high cadence, it will feel like you are bouncing all over the place. But once you get used to doing these at 120rpm, you'll be very smooth at 90rpm.

Some suggestions that I did not see above:

1. Check the crankarm length. Smaller women are going to have increasing difficulty turning large cranks at higher rpms. While there is controversy about this, 5.3 mm of crankarm length per inch of inseam length works well.

2. If your riding areas are not too hilly, get a tighter ratio cassette to keep the rpms in a desirable range--i.e., something more like 11-21 and less like 11-33. The closer ratios mean you don't have to spin up to as high a cadence to be ready for the next gear, because the gaps between the gears aren't as large.

For sporting tandem riding , i.e a competitive club ride, I have found best operation to be between 90 and 110 rpms, pushing higher than that for sprints, and perhaps down to 85 rpm or lower when just cruising.

Riders have to "write" pedaling software to get a smooth, bounce free pedaling stroke. You have to send instructions to your muscles before they are actually needed, owing to delays in the system. Two ways to do this are to 1) practice pedaling smoothly at a higher cadence than you actually need, perhaps up to 125-130 rpm or higher, and 2) practice one-legged pedaling at rpms that are high enough to be difficult. In practice, you unclip one foot and hold it away, while you pedal with the other leg. Pedaling with only one leg teaches you to pull smoothly all the way around the pedal circle, because you don't have the other leg to pull you around any spots where the leg wasn't working, usually on the back of the pedal circle or at the top or bottom. Practicing these skills may allow you to turn higher rpms without bouncing.

Turning up the preload on the shock-absorbing seatpost as mentioned above is a good idea. I would add that you needn't be confined to options that only include stock parts. On one occasion I needed a prompt solution to insufficient preload. I had already turned up the adjustment screw to its maximum, so I disassembled the seatpost and removed the relatively wimpy elastomer, and I replaced it with a stack of nickels. With only the spring and the nickels inside the seatpost, I turned the adjustment screw back up to the middle of the range, and we obtained excellent, bounce-free ride quality. From this experience I took away a valuable lesson: for road tandem riding, damping is sometimes overrated--you may only need enough preload for the weight on the saddle.

Thanks everyone for all the responses. I don't exactly understand all of them, but that's why my husband, the biker, is out raising up the seat a few mm. And we'll need to work up to the leg strength to practice at higher rpms (I got that one...) Hopefully the commute in to work in the morning will be better. Now if only you could help with the humidity...

My stoker likes the Thudbuster, but can't spin as fast as I can. If I tried to bring the candence too high for her, she started bouncing, and let me know it right away. This happened a lot when we first started on the tandem. Since then, I've adapted to keep my cadence down and she's raised her's, so it's rarely an issue any more.

+1. Probably the real answer, IMHO.

Steve

+1 on that, if the seat is in the right spot, the pedal motion is crucial to not create bouncing.

Started racing with experienced pilots and got lots of advices and tips to correct/improve pedal stroke, and that should prevent the bouncing, even at higher cadence.

IMO the solution is not to decrease the cadence.

What Type of Suspension Seat Post?
 

My stoker/wife rejected suspension seat posts for years due to bouncing at high (105+) cadence, but remained frustrated with bumps. Several years ago we added a full suspension MTB tandem to the stable and she became a fan of plush rides. We've gone to a Thudbuster ST (lighter & allows shorter section of extended seat post than the original model) on our road tandem and while it took a week to dial in the seat height she's now able to spin at 110 without bouncing for short intervals and cruise for hours at 95 - 105.

As noted in the previous posts there are several things to work on:

1. If you want to keep a suspension post make sure you get a good one that can accomodate high cadence (I'd recomend the Thubuster ST because it tends to maintain almost the same "seat to pedal distance" in compression by moving back rather than down).

2. The seat height that works may not be the same as on your single bike. My stoker finds a greater seat height comfortable on the tandem.

3. If high cadence is important to you and your captain - train for it. The best training for high cadence that I know of is time spent on rollers where you'll develop a silky smooth pedaling style (admittedly after some frustration - but keep at it and it will come). Rollers are much better for this than stationary bikes, spin bikes, trainers, etc. because you're training both your spin and your balance. As the two improve together you can start high cadence intervals on the rollers and the tandem.

Good luck!

Howard

I think all the above are good suggestions but the main question is: Are you able to spin on your single bike at the RPM that your captain demands on the tandem? If not: practice and shorter crank arms will eventually help. In the interim, your captain needs to compromise on an intermediate cadence.

Hello all, Thank you for your continued ideas. I feel I need to clarify things a bit though. The sum total of my biking experience is toodling around on a tandem 25 years ago while an undergraduate student in Illinois. After our first daughter was born, we threw a kids plastic seat on the back and toodled a bit more. But when she hit 2, I pretty well stopped. For no real reason, just no more riding. And that's been it until this April. We've put 350 miles on a tandem this year, mainly on the bike paths to and from work and a couple mild extended rides. So all this business about cadence and spinning and seat posts and saddle heights and rollers and all that - well, that's nice for y'all, but I'm just moving out of "toodling" mode and I'd like to not bounce. :) So that 42 miles we rode yesterday - well, that was something else again...

Shelly

Stoker wanted an alternative to the standard suspension seat post within a few weeks, we have found the Thudbuster ST to be great. We have contemplated a Carbon seat post (maybe a specialized one with the elastomer dampner insert), but she seems to be happy for now.

We can comfortable handle 85-90 rpm with short burst of 110+ rpm (mainly because she is a bit of a grinder on her single)