Shooky56

Was kind of interesting to read the "arguments of opinion" from those who discounted it but never ridden one. I agreed and likely done the same myself but I would (based on a survey of one) been incorrect.

My friend, doctor and cycling buddy owns 11 bikes and has purchased half again that many that he has sold. He has only ridden road bikes for exercise and cycles about 4-5K miles each year. He bought a specialized bike with the Zertz inserts. We have tar and chip roads around here for much of our routes. They're generally pretty smooth but there's that constant rumble of road feedback. He says the difference is "amazing". On top of that, he's ridden solo TT's on one of our courses (19.6 miles) and broke his 10 year old record by roughly 1 minute. The bike has nothing special over his older ones (wheels basically same profile etc) EXCEPT energy losses to vertical displacement of unsprung mass. That is, of course, my opinion only but I'm a national TT medalist and cannot for the life of me see anything special about that bike except those inserts. They wouldn't help a bit if the course were silky smooth but it reminds me of my change from an aluminum to carbon fork. My smooth courses were the same speed but my rough courses got substantially faster (about 1 mph sustained over the rough surface).

shadowcyc

Do have any idea about quality of Zerts ? is there any deformation, that depends on usage ?

regards

unterhausen

This is a really old thread, are there still bikes made with these inserts? It seems to me that the problem they were meant to solve, road vibration, has been solved by most carbon builders in other ways.

NYMXer

Another structural engineer chiming in and I just wanted to add that there is a "cancelling" effect at the split, and that is what does the job. It is not as significant as adding a shock (due to several factors, isolation being one, as in a motor mount) but there is a ride improvement via a simple concept.

At the end of the day (or ride), if it works for you then it is worth it. The Roubaix is a great bike and rides smooth, but so do other bikes without the Zertz.

BTW, I own a Roubaix, lol

clasher

I took an older roubaix out for a spin yesterday and it wasn't much different from my vintage steel roadie as far as road buzz, the roubaix had harsh 23mm tires though and I had supple 25mm open corsas on the road bike and the ride was pretty similar.

prathmann

If you're referring to the potential for destructive interference of the vibrational waves, then note that 'Smokester' already correctly addressed that claim in post #8 . Sounds good until you estimate the wavelengths involved in vibrating bike tubes.

deapee

lol...The zertz itself isn't absorbing the force, you guys are correct in saying carbon handles it -- the design of the carbon frame allows the carbon to flex more -- the zertz insert is there to fill in the gaps. It could probably be filled with bubble gum and the cutouts in the carbon frame would still be functional. I don't pretend to know the structural integrity of the zertz, and any "engineer" that does, other than one who worked on designing the zertz inserts and makes a statement on it is doing just that; pretending.

To say the zertz inserts / cutouts do nothing is a joke. If you put your fingers on each side of the zertz, you can feel the carbon flexing / moving independently of one another and thus absorbing. Anyone who denies the efficacy of the zertz is probably just a hater.

That being said...a 28mm tire vs a 25mm tire would probably smooth the ride more...but that's not what the topic is about.

unterhausen

it is possible to make rubber absorb energy, I used to have a ball that you could throw at the floor, and it wouldn't bounce. Are there bicycles available with these inserts in bike shops?

clasher

The specialized roubaix and sirrus both have zertz in them according to the website. I would guess that "zertz" is a trademark of theirs.

dim

I ride a cheap aluminum road bike with steel forks for my daily commuting.... it feels like operating a jackhammer on bumpy roads... on flat roads, it's fast and a pleasure to ride

I rode a friend's one (exact same bike), but he has a carbon fork .... huge difference .... so much so, that I am seriously looking at the same carbon fork for my bike

the nice thing with my bike, is that it's a good cheap one, and when I lock it up in the city, the bike thieves don't bother. (I live in a high bike theft area and I need to lock my bike in public places)

so... what I'm trying to say, is that the fork makes a big difference

my other bike is a Surly Long Haul Trucker with steel forks .... main difference being is that the fork is 'swept' and not straight.... it also has wider tyres .... an absolute pleasure to ride, and it rides like a Lexus LS400

unterhausen

a cheap steel fork is going to be a lot stiffer than an expensive steel fork. I would think that a LHT fork is still going to be relatively stiff. It's a budget bike built for heavy loads.

dim

the curve of the steel fork makes a difference ... thats why some of the pashley steel forks are curved ... and they ride like cadillacs .... The surly LHT forks are also curved/swept but not as much as Pashley but still very effective on bumpy roads:


you can have any saddle/seatpost, but the ride depends on the forks .... a crap fork and you will feel all the vibrations through your arms IMHO

the surly is a budget bike because when you buy it off the shelf, it's basically a skeleton(but saying budget, £1300 ($1900 USD) is not cheap considering what you get) .... start customising it with fenders, decent saddle, etc etc and it's not so cheap

they sell them like this, because everyone has different aspirations/ideas on how they want to customise their bike .... I could have (and seriously considerded) a Koga world traveller, but opted for a surly LHT because IMHO the surly is a much better bike when customised