Felt Z1, Part II

The Z’s bottom bracket is massive. To be any broader Felt would need to move to BB30.

When I found out that the Z1 frame was tipping the scales at 900g, I knew I wanted to review one. My first trip out on one came in borrowing one belonging to one of Felt’s staffers. In two rides I knew I needed to experience more.

I arranged for a frameset rather than complete bike. I had a Campy group sort of lying around waiting to go on a bike. Doing reviews this way cuts the expense for a bike company pretty radically and while I had done this on a number of occasions previously, that’s not quite what I did here. Spoiler alert: I bought the frameset.

With that out of the way, here’s why: When it comes to my views on frame geometry, high performance carbon fiber construction and weight, the Z1 comes very close to everything I want in a bike. Traditionally, my preferences have been for relatively low weight, a longish wheelbase, a tad more trail and good torsional stiffness. I also like a low bottom bracket, but as far as production frames go, that’s just a pipe dream on my part thanks to the CPSC. The Z, like all Felt road frames, has a 27cm-high BB.

As I see it, you have several alternatives. You can buy a heavier frame that will offer more impact/crash resistance. It may handle better, or it may not. It may have a superior road feel, or it may not. You can buy a frame with a lower BB, but it won’t be as light. Of course, you can choose to purchase a frame with a shorter wheelbase and less trail and those bikes abound.

That tiny carbon fiber “patch” (not their term) is where the chainstay is co-molded to the bottom bracket, yielding a strong joint that is much lighter than what would result with a traditional lug.

My preferences aside, in absolute terms, the Felt Z1 is a remarkable and rare bicycle. To my knowledge, it is the only grand touring frame that tips the scale at less than 1kg in a 56cm frame. Even the Cervelo RS weighs more than 1kg. And while weight isn’t everything, the bike’s weight comes with an important corollary. To be that light, the frame must employ a fairly ambitious blend of intermediate, high, and ultra-high modulus carbon fiber. This blend allows for exceptionally thin-walled tubes. As a result, the Z1 has a road feel that imparts much greater sensitivity than competitive models. As much as I like the Roubaix, the Z1 has a far superior road feel.

Among cycling cognoscenti there’s a certain mistrust of bike reviews. The joke goes, “and they said it was torsionally stiff and vertically compliant.” I think the reason these assessments don’t pass the BS meter is simple. Anyone who rode steel from the Columbus SL/Reynolds 531 era knows a thing or two about vertical compliance. And if you ever rode one of the bonded aluminum Alan or Guerciotti frames, then you know a lot about vertical compliance. Today’s top-shelf carbon fiber frames are stiffer than those old frames in every single dimension. Where they really differ is in the severity of road vibration they transmit. An equally stiff frame made from steel transmits more road vibration. What gets called “compliance” by most cyclists is really just vibration damping and the beauty of carbon fiber is that some carbon fiber frame have the ability to damp a broad spectrum of vibration so that the sensation isn’t so much wet blanket, but rather volume lowered. Kind of the opposite of the amp in “This Is Spinal Tap.”

Look, this one is turned down to five.

That said, there’s also some suspicion for the notion of torsional stiffness. To this I cry foul. When I began reviewing bikes I would spend some time making sure the shifting was adjusted perfectly to eliminate the ability of componentry to color my opinion of the frame building. It was only fair.

Next, I would take the bikes out and after I was warmed up I would do a few sprints in the 53×19 (assuming the cassette was a 12-23). On most frames, I could make the outer plate of the front derailleur rub against the chain. This was my standard litmus test for bottom bracket stiffness. On those occasions in which it didn’t rub, I knew I was dealing with a bike with a really stiff bottom bracket.

That didn’t happen much.

To resist torsional flex and twisting loads, the down tube is broadest on its underside, at the bottom bracket.

But bottom bracket flex isn’t the whole story. Not even most of it. Once manufacturers had largely addressed BB flex a whole new issue emerged: torsional flex. The issue is familiar to avid tandem riders. Those who rode tandem back in the days of small-diameter steel-tubed tandems will remember a phenomenon referred to as “lash.” Frame twist could be so pronounced as to cause the tandem to steer in one direction or another, making handling unpredictable. Compounding matters, wheels have gotten more flexible. Some 16- and 18-spoke wheels flex like the BB used to.

Carbon fiber frames still run the gamut on flex, mostly due to their forks. Some are sheetrock stiff while others are as flexible as bamboo shoots. Sit on the top tube of a bike and twist the handlebar and you’ll be surprised how often you’ll feel the bar twist slightly and the front wheel stand firm as the fork gives.

The fork on the Z1 is the same as Felt’s F1 with two minor changes. The dropouts are made from aluminum for increased durability while they are shaped slightly differently, giving the fork 50mm of offset. The steerer, the layup of the blades, all that is exactly the same.

This idea of creating exactly the same bike in two categories is significant to me. One thing I heard consistently from women when we reviewed bikes at Asphalt was that any time a bike was offered specifically to women it almost always featured either a watered down frame or parts pick. I knew a number of successful professionals who happened to be women and they felt consistently insulted by the fact that most of the time they couldn’t buy a bike made specifically for women that would also include a top-of-the-line parts pick of Record or Dura-Ace.

So one of my bigger pet peeves is an indication by a bike company that only racers will have reason to buy an ultra-light bike with Super Record or Dura-Ace. Honestly, how many people who are racing out can both afford Super Record and would choose to race it given how much of it is likely to disintegrate in a crash?

The carbon fiber blend that gives Felt’s F1 such a distinctive feel is present in the Z1 as well as their women’s frame, the ZW1. The ZW is essentially just Felt’s Z geometry in women’s sizing.

Other than a change to the dropouts, this is the same fork used on Felt’s F1 bike.

Back to that whole flex issue. Builders who chose to builde with Columbus tubing back in the 1980s had to choose on what size frames they would begin to blend Columbus’ heavier SP tube set in order to offset the stiffness loss of the larger frame sizes. It was not uncommon to find a 56cm frame built entirely from SL while the 58cm frame featured an SP down tube for some additional stiffness while the 60cm frame would be built entirely from SP. Well carbon fiber allows you to tailor each frame’s material usage to get exactly the right flex pattern.

Because there is no limiter forced by the raw materials, Felt changes the amount of material in each frame size of the F, Z and ZW bikes. Because the ZW bikes are the smallest frames intended for riders likely to be a bit lighter, the ZW1 is actually Felt’s lightest carbon fiber frame, weighing roughly 800 grams in its smallest size.

Why do this? Imagine having the ability to create frames that offer the same flex pattern in every size. Imagine knowing that your riding experience is the same as someone four inches taller … or shorter.

When shopping for bikes, fitting is the crapshoot. Until you take a serious look at the geometry, there’s no way to know if you can fit on a given bike. Between the Z-series frames and the ZW-series (women’s) frames, the Z is available in nine sizes. From smallest to largest, the top tube lengths are as follows: 49.7, 51.5, 52.5 and 54.5, for the women’s bikes and 52.5, 54.5, 56, 57.5 and 59.5cm for the men’s bikes. I could easily have ridden the 57.5cm top tube bike, but selected the 56 due to the length of the head tube and my desire to keep the bar relatively low, while avoiding the change in handling brought about by using a really short stem.

With only five sizes for the men’s bikes there are definitely some holes in the sizing run that could be problematic for some riders. The 1.5cm jumps aren’t too bad (or uncommon), but the 2cm jumps between the 52.5cm and 54.5cm top tube bikes could pose a fitting issue, as could the 2cm jump between the 57.5cm and 59.5cm top tube bikes.

Let’s talk absolutes. I’ve ridden frames stiffer than the Z1. I’ve not ridden one lighter in a 56cm frame—my frame weighed in at 908g. It’s in a dead heat with the best frames I’ve ridden in terms of ride quality. It retails for $2599, about $200 more than Cervelo’s RS and $100 less than Specialized’s Roubaix SL2.

By creating two bikes so very similar in so many aspects, the folks at Felt brought focus to a point that doesn’t get much attention these days: geometry. At the end of the day, the only meaningful differences between the F1 and Z1 are how they handle.

The Z1 reminds me of nothing so much as the Italian road bikes I often reviewed a dozen years ago. It’s calm in a straight line, turns in easily and is responsive in a sprint.

The wishbone junction is clean and features simple lines.

It was at the Markleeville Death Ride nearly Lake Tahoe that I had a revelatory experience. Descending Carson Pass in a painful hail storm (I know, that’s redundant) I began to catch a 3-series Beamer at 40 mph. I couldn’t see much other than the yellow lines to my left and the white line on my right and yet I felt calm and secure. The Z1 was rock solid.

The bike’s only weakness emerges at truly high speeds. I’ve found that once I’m above 45 mph the front end starts to get a little loose, twitchy. I haven’t experienced anything as bad as a speed wobble at those high speeds, but the bike’s unperturbable nature begins to falter. In the grand scheme that’s happened fewer than 10 times and I have more than 2000 miles on this frame.

The bike industry is full of good, if ordinary, bikes. There are a number of impressive bikes as well. There are a handful of truly extraordinary bikes. The shame is that Felt’s Z1 could easily be lost among not the ordinary, but the impressive. It’s far more than that.

(A quick note on bike scores: I’ve decided I’m going to score bikes a little more stringently than I did in some of my previous reviews. I’ve revised those scores down and scores in the future will reflect that as well.)

Felt Z1: 95 points

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14 comments

  1. Rich

    Really interesting reading especially as I have borrowed a friends F series bike. Frankly it’s left me stunned by the quality of the ride. I read sme rumours that some of the Pros ran the Z with the F fork t get the shape & handling they where looking for. As you know the guys at Felt are you able to shed any light on the subject. Great review, makes me want to try one.


    1. Author
      Padraig

      Mark: You’re right that in frame design 86mm is the “new” standard. The issue, as discussed by the engineers I’ve spoken to is whether the BB30 spindle offers enough advantages to make going to the wider design worthwhile. The press-fit bearings of BB86 aren’t how most companies seem to be discussing the issue. So, yes, you’re right, but I’m trying to stick with the terminology most of the industry seems to be using.

  2. MattS

    This is a great post. For me it furthers the conversation about frame design and ride quality in a very clear manner. One question remains though: what size tires can you fit in there? The grand touring bikes really are well suited to riding on varied surfaces. It would be a shame if the Felt won’t accept 28s. I’d personally love to see bikes like this accept 30s (which would take require a mid-reach brake, of course). I feel bad for all the riders out there riding aluminum cross bikes on dirt roads because their road bikes won’t take 25s let alone 28s.

    One more question: have you experienced similar twitchiness at speed on other bikes with very similar geometry? Curious about whether this trait should be attributed to the frame and fork’s flex characteristics, or perhaps even alignment rather than geometry.


    1. Author
      Padraig

      MattS: You can definitely get 25s in there and I believe you could get 28s in there, but I haven’t tried. Fitting 30s is pretty unlikely, though.

      It’s hard to say if this will be a consistent feature of the current grand touring bikes as a result of design. It’s definitely not a flex issue and I don’t think it’s an alignment issue; it tracks much too well when ridden no-hands.

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  4. MattS

    Padraig: good to hear 28s seem likely. 30s don’t tend to fit in standard reach brakes, so no surprise there.

    I don’t recall you talking about twitchiness on the Roubaix at high speeds. I’ve never experienced twitchiness on mine at any speed (up to 100k/hr), but I have to admit none of these descents were longer than a couple kilometers (and mine is the first generation model). I would have been using 28s on 32spoke Open Pro wheels – i.e., not light. Wondering whether the distribution of weight is the issue. I’m 6’1″ and ride a 58 with a 120 stem (and bump up 1cm for the odd road race), zero offset post, which definitely gets plenty of weight over the front wheel. But from what I’ve read, your bikes have a very similar distribution of weight. It seems the reduced drop to the bars must play a role here, compared against a typical race bike. Also, bb drop has to figure to a degree, and you’ve mentioned no light grand touring framesets feature low bbs. So I’m wondering whether the combination of higher bar and higher bb than the bikes you’ve liked most for descending might be the design elements that contribute to this unsettling trait at speed?


    1. Author
      Padraig

      MattS: The descent that I’ve done the most on the Z1 in which I detected the twitchiness—Tuna Canyon, for those of you who know Malibu—was one that I think I only took the Roubaix down once and I can’t specifically remember it getting twitchy. They both performed very well on Decker Canyon, but what I remember most from those descents was that the Tarmac was calmest of the bunch. The Roubaix does feature a 2mm lower BB in the 56cm size as compared to the Felt. Not huge, but a difference nonetheless.

      Regarding setup: I’ve got long legs and a shortish femur, so my saddle is fairly far forward on the rails. I try to set up all my bikes as similarly as possible, with the goal being 56-57cm of reach from the nose of the saddle to the center of the bar and 5-7cm of drop from the saddle to the bar. Because I can never get bikes to be exactly the same, I have to remain somewhat flexible on that final mix. One bike might have a bit more reach and less drop while another might have less reach and more drop.

      The goal is always good fit with great weight distribution. I’m not a great climber anymore, though I continue to work on it, but I love to go downhill fast. It is absolutely the best test of a bike’s handling and any time I’m on the bubble between two sizes, I’ll almost always take the smaller of the two bikes just to make sure I can get a lot of weight on the front wheel.

  5. mark

    Padraig, with all due respect, your explanation still doesn’t make sense to me. All I was saying is that BB86 would enable a wider bottom bracket area while BB30 would not, since BB30 isn’t wider (it has a higher diameter spindle and internal bearing cups, so it’s actually narrower). I’ll let the engineers debate which standard is stiffer, but the likely reason many bike companies are only discussing BB30 is because it’s an open standard.


    1. Author
      Padraig

      Mark: Maybe the way I should phrase it is that folks are saying BB30 when what they really mean is any wider BB shell. There are so many standards out now that the conversation is often couched as “BB30 or something like it” and they just end up saying BB30. The move from external cups and bearings to press-fit bearings is the larger goal as that will allow for a larger BB area in the frame’s design. As you point out, BB30 is an open standard and that’s attractive to many manufacturers.

  6. mark

    “Maybe the way I should phrase it is that folks are saying BB30 when what they really mean is any wider BB shell.”

    This makes a lot more sense. Will be interesting to see how things develop since neither Shimano nor Campy makes a BB30 crank. Both can be used in a BB30 frame with inserts to accept outboard bearings, but that sort of defeats the purpose of incorporating BB30 into the design.

  7. Dave

    You mentioned that you prefer bikes with more trail, and while you never actually said the Z has more than average trail I felt like you were implying it. So I just want to clarify that the Z series uses less trail than most bikes today, and unlike the Roubaix, Synapse, etc which use more trail. A HT angle of 72.5 and rake of 50mm, with 23mm tires would yield a trail of 54.1mm, and a mechanical trail of 51.6mm. With stock 25mm tires you would get 54.7, and 52.2 respectively.


    1. Author
      Padraig

      Mac: I reviewed the Colnago CLX 2.0 and hated that bike. It’s unlikely I’d come to kinder conclusions about the CLX 3.0. And just so you know, the Z1 reviewed here (this review dates from 2010) is the original version of the Z series bikes, not the newer version, which is a significantly refined and improved bike.

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