Community > Non-Thorn Related
Soliciting Suspension seatpost recommendations
Danneaux:
Hi All!
I'm considering a suspension seatpost for my Nomad Mk2 when I use it on logging roads without a load. Usually, I just post (stand up briefly) when hitting a bump with my unladen bikes on such terrain, but that is less-often possible when tootling along in low gears uphill with a full-on touring load. Despite what I initially thought, the front of the bike is not problem; I just bend my elbows and do fine with that. It is the compressive loads coming up my spine that have a whiplash effect on my neck and I can really feel that after several hours. Unlike when road riding, the size of the bumps makes tire cross-section and lower pressures less effective in absorbing the larger hits while seated. For road use or extended touring, I'd still choose a lower-maintenance rigid post, but a sus-post would really help when I'm riding the bumpy stuff in the hills and mountains that surround my town.
I have experience with two suspension seatposts on my tandem. The stoker gets a USE telescopic seatpost I heavily machined and modified to reduce stiction and uses a combinaton of elastomers and a repurposed automobile valve spring. It works well, but would not be to my taste for the Nomad because there is the slightest bit of rotation that can be felt while pedaling and I find that annoying. My stokers have all been very enthusiastic about it, and say it performs well even on the "bigger hits" experienced by stokers when going on rougher surfaces (the stoker sits nearer the rear wheel and so feel the bumps more than I do as Captain, suspended midway between a long wheelbase).
I have a different sort of sus-post at the Captain's saddle. It uses an elastomer in compression that works a bit like a broomstick in a door hinge. It is just the ticket for absorbing the little bit of "road buzz" that comes up through the long wheelbase to the captain's saddle. Its one drawback is it tips the saddle rearward on compression, so I have to set the saddle up with a bit more forward tilt than usual to compensate. Not a problem with the leather-covered Avocet Touring II saddle I use there.
I think I'd prefer a parallelogram seatpost on the Nomad for several reasons. For one, under compression, the saddle moves downward and rearward, making for a bit less vertical compression and so affects saddletop-to-BB distance a bit less. Second, the geometry seems likely to be a bit more responsive than a telescoping post, which is about halfway locked-out when examined in light of the compressive forces coming up through the rear wheel.
There's three leading candidates so far in my search, and all are available in 27.2mm to fit my Nomad's seatpost shim. Thudbuster has a long-travel parallelogram post with two tunable diagonally-placed elastomers. Thudbuster also offer a shorter-travel post whose parallelogram is filled with a single, shaped elastomer that comes in several durometers. These are both nice, have received stellar reviews for their respective intended usage, and are expensive.
Alternatively, SR-SunTour offer a parallelogram seatpost that has been freshly redesigned for 2012, the SP 12-NCX: http://www.flickr.com/photos/29976052@N08/8022574000/sizes/o/in/photostream/
...and...
http://www.srsuntour-cycling.com/index.php?screen=sh.detail&tnid=3731
The price is considerably less than Thudbusters', and the reviews have been uniformly good on this new model at German and Dutch online vendors and among the pedelec crowd, even in comparison to Thudbuster. Our own Stuntpilot has one on his Raven Torla, and was initially impressed by it and is gathering long-term data on its performance. In an earlier post, he mentioned setting his tension so his post was effectively a rigid until he hit a large bump. That appeals to me. At that time, the post made a clicking noise when it hit the rebound stop, but was infrequent enough to be no bother. The SunTour uses brass bushings and rebuild kits are readily available to keep them fresh.
One thing that concerns me about the SunTour post is the apparent lack of rebound control. It uses a very clever design where a roller vertically compresses a spring-loaded shaft. This makes for a low-friction, very responsive post, but I'm concerned its action might not be well-controlled. Here's a video showing it in action at a bike show: http://www.youtube.com/watch?v=hN8v_SEWPto
Wondering if any of you have experience with suspension seatposts, if you also prefer a parallelogram design over telescopic, and what you thoughts are on the SunTour versus Thudbuster(s) or perhaps some other model or design.
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EDIT: I just came across another possibility by German component supplier XLC: http://www.xlc-parts.de/produkte_detail_de,854,33700,detail.html
Google-translated to English here: http://translate.google.com/translate?sl=de&tl=en&js=n&prev=_t&hl=en&ie=UTF-8&u=http%3A%2F%2Fwww.xlc-parts.de%2Fprodukte_detail_de%2C854%2C33700%2Cdetail.html&act=url
It uses an elastomer with adjustable preload to produce only 25mm of travel inits parallelogram linkage.
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I should note I'd like a seatpost with considerable layback/setback to get a good position on the bike while clamping the saddle rails midway to reduce breakage. I currently use a Thorn/Zoom long-layback 'post and it works fine. Thanks in advance for sharing your thoughts.
Best,
Dan. (...who <Ungh!> could use something to help with the <Ungh!> larger bumps while touring on <Ungh!> really rough roads)
martinf:
Maybe try a Brooks Flyer saddle instead? Similar top to B17, but with fairly stiff springs.
I generally prefer B17 for my bikes, but have a B66 Champion (the twin-rail predecessor to the Flyer) on my old 5-speed. On off-road riding I find this smooths out the worst of the bumps without noticeably compromising on-road pedalling efficiency.
Had the B66 Champion since 1984, done over 60,000 kms with it, the leather is a bit cracked now but the saddle is still very comfortable.
Downsides of a sprung saddle - extra weight, and may make creaky sounds. But probably simpler than a suspension seatpost, and doesn't develop sloppiness with wear over time.
Danneaux:
--- Quote ---Maybe try a Brooks Flyer saddle instead? Similar top to B17, but with fairly stiff springs.
--- End quote ---
Thanks for the thoughtful suggestion, Martin! I really wish this would work as a solution for me, as it is simpler and more direct, just as you say.
I tried a Flyer some years ago, and sadly ended up selling it to my neighbor. I found the springs were just too stiff to provide much (any) suspension effect for me even on larger bumps with my back at a 45° angle.
Similar experiences here: http://www.bikeforums.net/showthread.php/227872-Brooks-saddle-springs-%96-is-ride-softer-with-use
I really liked the idea, and wished very much I could have substituted slightly softer springs to make it work on muting the Big Bumps without bouncing much on the smaller ones. The B.17 is the perfect match in width and shape for my needs, and the Flyer felt the same. I really wouldn't want to go wider or narrower in the Brooks line, or to a different shape when this works so well for me.
--- Quote ---Downsides of a sprung saddle - extra weight, and may make creaky sounds. But probably simpler than a suspension seatpost, and doesn't develop sloppiness with wear over time.
--- End quote ---
All very true. I'd sure be willing to give a Flyer another try if I could just source the slightly softer springs I would need -- and then get then installed.
Best,
Dan. (...who may give this some more considered thought, as it is a Preferred Solution™)
geocycle:
I think a lot depends on your saddle. I didn't get on well with combining my B17 with a suspension post. I think it slowed down the break-in process. Also, for me getting the height of the saddle just right is critical for a Brooks and also for my knees. We are talking mm here! With a suspension post the height and geometry becomes variable. i suppose a sprung flyer or B67 would have some of the same issues but not tried them.
martinf:
According to this reviewer, the springs in recent saddles are stiffer than those in my old saddle:
http://swhs.home.xs4all.nl/fiets/tests/zadels/index_en.html#Brooks_b66_champion
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