Is elastomer the best solution
for a suspension seatpost?
If you want to improve rear end comfort of your bike you have a lot of options. Ergon / Canyon flexing seatpost, Specialized CG-R seatpost, spring based Kinekt 2.1 or upcoming Shockstop suspension seatpost are most noticeably examples. But there is one more: a elastomer based eeSilk from Cane Creek. I bought one to see how well it works in comparison to my Ergon CF3 Pro seatpost.
I like a lot my current suspension seatpost from Ergon. It offers up to 20 mm movement and simply looks cool. But I am still very interested in finding if it is the best one on the market. I already tested Kinekt 2.1 and found out that although it can provide better comfort overall it has drawbacks (springiness and bottoming out) that are stopping me from using it on everyday basis. Cane Creek with its elastomer based eeSilk suspension seatpost looked, at least on paper, as something that could finally beat my current seatpost. It also offers about 20 mm suspension but achieves this not through a carbon leafs movement but by using a elastomer which is put inside a clever moving construction that allows it to be freely squeezed when we hit bumps but also keeps the saddle leveled through that movement. It even uses a titanium bolts to make everything reliable in long term. And to be honest the construction indeed looks rock solid and it should be very durable. Some of the reviewers reported a small side movements but I did not felt anything like that. Everything works well and very silently. Just as you would expect from a thing costing about 300 euro…
So it is well made but how does it feel in use?
eeSilk uses a elastomers to provide the suspension. And they are not very big so the amount of movement they provide can be sometimes limited. In the result on a big bumps you will feel that eeSilk reaches it limits – you feel the sensation of bottoming out but this is nowhere near a real bottoming out that you can experience on something like Kinekt 2.1. There is no noise when this occurs either but compared to my Ergon flexing seatpost the end of the suspension movement is subjectively more harsh (again this is due to the limited amount of travel that small elastomer can provide). It is not a big difference but I can definitely feel it when riding on a bumpy forest route.
The other difference is in the way you perceive the suspension itself. A few weeks ago I had the opportunity to test the carbon GT Grade Expert bike and when I compared it to my steel Jamis Renegade I said that carbon frame offers a very comfortable yet muted ride. On the other hand a steel bike is more springy and engaging. The same comparison can be applied here. Cane Creek eeSilk elastomer based suspension is like a good carbon frame that offers you a great amount of comfort but at the cost of slightly muted feel of the ride while a Ergon spring based suspension seatpost is like a good old lively steel frame. By no means this is a bad thing but you have to be aware of this difference and choose what you like best.
OK, lets talk about comfort now!
eeSilk ships with a selection of 3 elastomers. First (number 3) is for riders between 45 and 73 kg, second (number 5) is for 68 – 95 kg and the third (number 7): 90 – 118 kg. On the seatpost itself Cane Creek mounted the middle so with my weight of roughly 84 kg I was ready to go and test it right away. The vibrations reading that I got on my benchmark bike (Soma Cazadero 700x42c tires run at 30 psi and a Lauf Grit SL with ShockStop stem at front) was very similar to my Ergon seatpost. On a fast gravel route eeSilk was exactly as comfortable and on a bumpy forest route a slightly less (3,8% less to be exact).
Based on my experience with a ShockStop suspension stem which also is based on elastomers I also wanted to know how eeSilk will behave on an elastomer dedicated to lighter riders (45-73 kg). So I changed the stock elastomer and rerun the test. This time I got the same level of comfort on a bumpy forest route and over 5% improvement on a fast gravel route compared to my Ergon seatpost. But to be honest the riding characteristic also changed – I was definitely feeling that elastomer is squashed quite badly just from me sitting on the saddle so it is no surprise that riding on it felt strange – I was constantly looking for my back tire to be 100% sure that it still is properly inflated. And this is the thing that Cane Creek can definitely improve. I really believe that elastomers are a very good solution for suspension seatpost but you should have more option of them to really find the best one for you (for me it would be something exactly between the 3 and a 5).
Do I recommend it?
Having a option of easily changing the elastomers to find the best one for you is a great advantage over a solutions like my Ergon seatpost where you got just one setup and either it will fork for you or not. But to fully use that advantage I believe you should have a greater selection of elastomers to play with. For now you have 3 in the package and maybe it will be more than enough for you but I found that I need more. It would be also beneficial if the eeSilk was available in different seatpost sizes (right now it is only 27,2 mm). But it weights only 295 grams (which is far less than Kinekt 2.1 that I also tested) and is Di2 battery compatible. The other great think about it is that it provides a modest 8 mm setback while my Ergon, to make the most of the flexing carbon leafs, has a 25 mm setback which creates a challenge to properly set up the saddle (of course you can buy a very similar Canyon VCLS 2.0 seatpost in 10 mm setback variant but Canyon itself say that it will be less effective in damping the vibrations). So when you don’t want a seatpost with a big setback and you don’t like to feel any bounciness that is assosiated with a spring based solutions like my Ergon of Kinekt 2.1, then eeSilk seatpost definetely looks like the best choice right now…