Carbonfiberboy 

We just rode a century with Stoker's brand new Specialized Oura Expert saddle. Total success. Stoker said the saddle "disappears." No butt or other soreness during or after. She has aero bars and has to slide back on the saddle to use them comfortably, but that's fine. Only thing is, there's less padding than her previous Lithia saddle, so I think a carbon seat post is in her future. Specialized CG-R if I can find one.

gracehowler

Seems to me less is always more! So does she use a thudbuster or? or are you thinking the gain from carbon pot will be enough?
R&J

Carbonfiberboy 

She has a telescoping post that responds to the big hits but because of internal friction, not so much to the small ones. There's more small stuff than big stuff, so I'm thinking a CG-R would be an improvement. From watching other stokers on Thudbusters, I'm thinking they rob power. Maybe my stoker is smooth enough for that not to matter, or maybe not.

gracehowler

I would like to hear more of your thoughts on power robbing, specifics?
R

Carbonfiberboy 

It's my observation that many stokers with Thudbusters bounce in the saddle, even at relatively low cadences. I believe this is simply a consequence of pushing down on the pedal and Newton's Third Law. Push down, stoker goes up. It seems to me that this robs some power from the seated downstroke. This is similar to the problem with Softride beams but on a much smaller scale. I believe that neither the captain nor the stoker knows that the stoker is bouncing. I certainly don't mention it, either.

Bad1

if that's the case these teams aren't down with the Zen of Tandem Riding!

fietsbob

Psychology may be involved. they may asked to put in the Elastomer in densities of what the want to weigh ,
Or want to admit to weighing, instead of picking one which has what they Do weigh,
and that weight at the lower end of the weight scale range for that particular elatomer ..

in other words bump up the elastomer choice , to a higher density..

diabloridr

When my stoker did a test ride on a suspension seatpost she thought it impacted her ability to produce power.

Fortunately she is happy with her rigid post.

waynesulak

I think that having a variable seatpost height would impact my power output and my enjoyment of riding.

Dean V

What is the need for a suspension seat post anyway? Tandems give a softer ride than single bikes and not many of them see the need for them.

reburns

Tandems give a softer ride for the captain mounted midway between the wheels of a long frame, but the stoker is mounted almost directly above the rear wheel and bumps to that wheel are transmitted fairly directly into the stoker's seatpost. Coupled with the fact that the stoker cannot see the bumps coming, the ride can feel harsher for the stoker than for the captain or a single rider.

My stoker is very happy with her Thudbuster, and I certainly never sensed any loss of power when we installed it. If anything, our endurance has increased. As captain, I am also more relaxed because I don't have to be quite as concerned about calling out every bump.

LastKraftWagen

Typical tandem geometry puts the stoker's weight more directly over the rear wheel, it's not nearly as "soft" as the captain's cockpit or being on a similarly designed (materials and geometry) single bike. Plus ride back there just once with a pilot who doesn't call out bumps and the 'buster would be much more appreciated. Final thought, if your stoker wants it, install it, you'll be a much aappier team.

LKW

waynesulak

I agree with that final thought. If the stoker wants it then get it. I know don't want my stoker telling me what to use on my end of the bike.

The main problem is the stoker's limited visibility and complete lack of control avoiding bumps. A bump is one thing but surprise bumps are much worse. In addition many stokers sit in a more upright position than the captain does placing a higher percentage of their weight on the saddle and less on the pedals and bars. You can feel this effect by riding your single as upright as possible on a bumpy road. The bumps feel bigger than the same road ridden in the normal manner.

I don't think tandem geometry is a problem. Tandem's generally have longer chainstays than modern single bike so the stoker is not as directly over the rear wheel as rider on a modern single bike. To that extend the stoker gets some benefit from a slightly longer wheelbase. It is just that the small benefit is outweighed by the problems mentioned above.

LastKraftWagen

Geometry may just be my issue, and admittedly my cockpit isn't custom fit to me, but my "sit bones" on the tandem are a full 4" closer to the plumbline of the rear QR than on my single [in the trainer]. I didn't measure BB to QR center-to-center, but I do guess I have to have more chain put on the tandem [I thought it was because of the dinner plate chainrings and cogs I use] Regardless, I expect vertical forces applied to the rear wheel effect the stoker far more than those applied to the pilot regardless of wheel???

PS: I don't personally bust the thud,

qspencer

That's correct. Consider a stationary tandem where the front wheel is fixed in place and the rear wheel is raised by some fixed distance. The entire system is pivoting around the front axle, so the resulting height increase of the front and rear seats will be proportional to their relative distances from the front axle. I'm just guessing here, but maybe the front seat is 50% of the distance to the rear axle and the rear seat is 90% on an average tandem. A 1 cm bump affecting the rear wheel therefore causes a 9mm bump in the rear seat and 5 mm bump in the front seat. It's a big difference, and even relatively significant changes in the geometry of the tandem would have relatively small effects on that ratio.

In a similar way, front wheel bumps affect the pilot much more than the stoker, but vibration to the hands has always been less of an issue for most cyclists than vibration to the sit bones.

waynesulak

Wow! I am not sure how this can be the case. Is you tandem an old one with a curved stoker seat tube? If so I did not consider that type of tandem in my statement since they are not very common.

LastKraftWagen

No, a 2000ish Duet, but with a setback post and the seat slid all the way rearward on the rails. I'm a "funny" fit (an LBS quote, not mine). Longer than typical laid back seatposts and insanely short stems (on singles). Larger frames just mean even shorter stems. It takes all that to get my knees positioned properly.

Broke out the tape since now you have me curious, BBs to QRs are actually within an inch, tandem crankarms are shorter, and outdoor (i.e. tandem shoes) have the cleats positioned farther forward. Good thing I wasn't cutting anything because the 4" measurement is actually about 3" (my bad, tactile measuring tape and my finger must have moved). The seat staysand seat tube are shorter on te tandem, so maybe the seat angle is [closer to the horizontal]. Or, maybe I really should have failed geometry.

Clarabelle

Well said!

Dean V

I usually ride as captain but I have stoked on a number of occasions. Usually on one of those "harsh" riding C'dales. It is definitely a softer ride back there than on my solo bikes.

Carbonfiberboy 

I did change my stoker's seatpost to complement the new saddle. I took off her RockShox telescoping post and put on a Specialized CG-R or CoblGoblr. Notwithstanding rules against major changes before a long ride, we did a 200k on the bike the next day. Stoker loved the new post. She said it made bumps she would have really felt just disappear.