Suspension Seat-posts on Ebikes

September 4, 2013

I own a Thudbuster, and I paid full retail price for it…long before I began writing about E-bikes. If you ride a hardtail bike (whether electric or “pedal-only”), I think a serious suspension seat-post is the best single purchase you can make to improve the bicycling experience.

At that time, there were really no other options. I had ridden a bike with a fairly common and cheap “tube within a tube” style that is frequently found on the less-expensive bikes sold at big box stores. This style definitely helped, but it’s feel was very disappointing for me, and I actually added a large cruiser seat that had two large springs built into it to help the inadequate performance.



There is nothing wrong with this common and cheap style, but if you buy one, don’t say I didn’t warn you.


Fast forward to now, and I have seen several new models with a variety of clever suspension designs that expand on the concept, providing more options.


First up is a seatpost that is sadly not in production any more. It had FOUR INCHES of travel! and riders who liked it said it not only had the longest travel ever put on a seatpost, its compression was very progressive (softer at the top of the stroke, firmer near the bottom). Because of the shape and orientation of the parallel links, the seat travel direction swings down and to the rear.

I occasionally see one sold as a used unit, but don’t hold your breath…they are rare.



The Moxey is no longer in production.


Tamer Pivot-Plus XC

The Tamer Pivot-Plus XC is available for purchase for about $120 retail (a price that’s similar to the Thudbuster), and in this picture you can see it also has a parallel-linkage to swing the seat movement down and to the rear. One of the links has a connecting rod, which transfers the downward-curving seat mount movement onto a coil-spring that is vertically positioned inside the seat-post.

I like the looks of this product, but I have not had a chance to try one of these. The pre-load can be adjusted and a different spring can be swapped-in to change the tension and rate, depending on the weight of the rider and the feel you desire.

The stroke length is 65mm / 2.6-inches



The Tamer Pivot Plus XC



The insides of the Pivot Plus XC


SR Suntour SP12 NCX

This suspension seatpost functions in a very similar fashion to the Pivot-Plus above. But, instead of a connecting rod, the forward link has a roller that presses against the top of the piston which asts as a spring-cap and a bushing. This piston covers the top of the coil spring, which is vertically mounted inside the seat-post. The trailing link has a rubber bumper to dampen the return to its top position.

The stroke is 2-inches / 50mm. They seem to be readily available at dealers in Europe right now, but I have found them in North America on Ebay for roughly $120.



The SR Suntour SP12 NCX


Cirrus BodyFloat 3.1

This is the most recent product in this category to become available. It was launched with a kickstarter campaign last year by Cirrus Cycles in Washington, and they are now available for approximately $349. It only has 1.5 inches of travel (38mm), but one of the issues it addresses is that long-stroke seatposts like the Thudbuster-LT sometimes position the seat too high for some riders to be able to set their feet on the ground at a stop.

It also uses two parallel linkages, but it uses two exposed coil-springs that are roughly horizontal. It’s very pricey, and we have not met anyone who has used one of these to get a feel for whether or not it is worth the premium.



The Cirrus Body Float 3.1


 Cane Creek Thudbuster

Finally, we arrive at the well-known Thudbuster. They can be purchased in a Long Travel (LT, 3-inches/76mm of travel) and Short Travel versions (ST, 1.3-inches/33mm). The retail price is $159, but they can be often be found on Ebay for approximately $130.

I have several bikes, and this was purchased for a hardtail that I own after friends recommended it to me. If I ever sold the bike, I would keep the Thudbuster. If I had the opportunity to try out some of these other new options, I might change my mind, but…until then this remains the single most important purchase I have added to this bike (other than helmet, gloves, and sport-glasses). If you have back problems, you might consider a full-suspension frame, or even a recumbent. But, even young adults with healthy spines should seriously consider how an unexpected hit on a large pothole would affect their lives.

The LT uses two rubber plugs, called “elastomers”. These elastomers can be swapped out for different ones that are firmer or softer. The ST version has an X-shaped elastomer, and during the seats downward stroke, it stretches in one direction, while it compresses in the other.



The Cane Creek Thudbuster. The Short Travel (ST) is on the left, and the Long Travel (LT) is on the right.


Here is a very rare Evinrude bicycle from many decades ago. Evinrude became famous as a manufacturer of outboard motors for lake-fishing boats. The seat-post slides up and down inside the seat-tube. Pic is courtesy of “Lipstick and Wrenches“, a classic bicycle facebook group.



A very rare Evinrude bicycle from the pre-WWII era.


Written by Ron / Spinningmagnets, September 2013

Grew up in Los Angeles California, US Navy submarine mechanic from 1977-81/SanDiego, Hydraulic mechanic in the 1980's/Los Angeles, Heavy equipment operator in the 1990's/traveled to various locations, Dump truck driver in the 2000's/SW Utah, Water Plant operator since 2010/NW Kansas

  • deVries

    Hi Spinning, which Thudbuster are you using? And, have you tried different inserts for the version of TB you have? If you did not get the LT version, then why not? Thanks.

  • Daniele

    an other aspect to consider must be the horizontal shift, first times could be annoying to drive. Then you will get used. So instead to measure only the vertical ‘travel’ is need to consider even the horizontal due to geometry. I pretty satisfied of my Sountur SP8 but there are some limit with a full-suspension bike.

  • lkoerjtopied

    Or, of course, one could use a suspension seat, which pretty well eliminates all the issues with seat-post type suspensions…

    • cal3thousand

      … while addressing none of the issues. A suspension seat does not have any appreciable travel to dampen oscillations.

  • andrewkewley

    I have a LT thudbuster and it makes a big difference, but… It wears out in <5000km and turns into a creaky sob, even if you keep lubricating it as they recommend.

  • lete77

    Personally I have had 3 versions of Suntour. I ride 200kms a week. The cheap $30 ones with a spring, biggest waste of money. 2nd, I bought the older version of the NCX and it had plastic bushes which after a year broke. Now I am into the 3rd instalment, the NCX which is above in this post, it’s great! works the same as the previous model but better built, you can see it now has brass bushes. Due to the sturdier build it’s heavier than the previous model. Bought it in June last year and still going strong. At the time is was 65.76 EUR from XXcycle. Great investment. I haven’t used the Thudbuster but I was riding behind someone one day and I could see while pedaling on a flat surface it bounces up and down. You don’t get that with the NCX. Plus the Thudbuster is expensive!
    Hope this review helps…

    • cal3thousand

      I’ve had both the Thudbuster LT and an NCX. I sold the Thudbuster after getting the NCX after I found the performance to be just as good or even better. Thudbuster’s only advantage in my eyes is the adjustable elastomer. But that doesn’t change dampening rate, only spring rate.

      I’ve been using the NCX for nearly a year now and it has been very good and still works well.

    • pascal


    • pascal

      BEWARE, SUNTOUR is not compatible with saddle Brooks B17 !!!!

      • eBikeChick

        Pascal, that’s not true. I just saw a picture of someone’s touring bike online and he is using a Suntour NCX-12 seat post with a Brooks B17 Select saddle, and quite successfully.

  • j3tch1u

    now running the NCX on Duty Cycle…it has a much more progressive feel than the Thudbuster.

  • cal3thousand

    I just wanted to report back that the NCX on my wife’s bike was acting weird and not giving much suspension action. I think the term is stiction.

    So, I just broke out some grease for the piston, which helped marginally. But then using WD-40 on the linkages instantly returned the “action” I was expecting and stopped any signs of noise.

    If your seat is not working as you’d like, take 5 minutes and lube it up!

    • ..

      Sounds good but I’d point out for anyone reading this that WD40 doesn’t seem to be a lubricant but a water displacer! Try GT-85.

  • Frostbite

    What do you think, Thudbuster LT or Suntour NCX for -20°C environment? (That’s -4 °F)

  • JudaDE

    been using the NCX for a couple of weeks now… really, really happy with it. Did an e-bike conversion with a hard tail. The NCX has made a world of difference riding on/off sidewalks in urban/city streets commuting to work.. Can’t recommend it enough.

  • ..

    I got a bog standard spring type post for $12 – it is good enough (in combination with my Selle Royale Respiro Relaxed seat which has elastomers and gel padding and a big groove so your sensitive bits aren’t touching the seat.) Before the post, any bump in the road would make my head rock up and down on my spine (upright seating bike) – after 1/2 hr of that I’d have a headache. The spring stopped all that.