Tubesets for Our Bikes: Oversized

In addition to individual Kaisei frame tubes, Compass Cycles offers three complete tubesets: Superlight, ‘Mule’ and Oversize. Each tubeset is based on bikes that we have found to work extremely well. The Superlight set is the lightest steel tubeset available today, great for riders who prefer a flexible frame. The ‘Mule’ set uses an oversized down tube for a little firmer feel. It’s also better for carrying a front camping load.

The Oversize tubeset is made from thinwall oversized tubing to offer the ultimate performance for those who prefer a somewhat stiffer frame. BQ contributor and constructeur Hahn Rossman’s heavier build is accompanied by a higher power output, and he builds his own bikes with oversized tubing, both his randonneur bikes (above) and the cyclocross bikes he races with panache and passion.

The oversize top tube with ultra-thin 0.7-0.4-0.7 mm walls adds stiffness to the frame without detracting from its lively feel. Kaisei keeps the ‘belly’ of the down tube to a slightly more conservative 0.5 mm, instead of the ultra-thin 0.4 mm, because the large-diameter tubes dent too easily when they are too thin. (Down tubes are larger than top tubes, making them less convex and easier to dent.) Since our tubes are available with longer ‘bellies,’ they are still lighter than other tubes with thinner-wall, but shorter, bellies.

How does a bike made with the Oversize tubeset ride? I’ve ridden Hahn’s bikes – we share the same bike fit – and they feel subtly different from mine. They still ‘plane’ – by most standards, this tubeset is very light and still has flex in the right places – but they do have a more planted feel. For me, they work best with a higher power output and a slightly lower cadence.

Interestingly, descending feels the same on all our bikes, regardless of the tubes used in the frame. We’ve found that frame stiffness makes little difference in how a bike handles – which makes sense when you consider that there are no significant side loads on a frame when you aren’t pedaling.

The Oversize tubeset is a great choice if you want or need a little more stiffness in your frame than our other Kaisei tubesets offer. That makes it perfect for tall, heavy and/or strong riders. This is also the tubeset I’d chose for a camping bike that carries rear panniers in addition to a front load.

Of the three tubesets we offer, which is best for you really depends on your build, riding style, preference, and intended use of the bike. They all offer excellent performance that comes with a carefully designed balance of frame stiffness. As a Compass exclusive, we offer the Kaisei tubesets in two lengths, so you can get tubes optimized for your frame size. All tubes we sell feature Kaisei’s unmatched quality and experience that comes from supplying the tubes for the frames of thousands of professional Keirin racers. We import these tubes because we feel that there are no better tubes anywhere.

Further reading:

About Jan Heine, Editor, Bicycle Quarterly

Spirited rides that zig-zag across mountain ranges. Bicycle Quarterly magazine and its sister company, Compass Cycles, that turns our research into high-performance components for real-world riders.
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16 Responses to Tubesets for Our Bikes: Oversized

  1. Richard says:

    The idea that how a frame handles is unrelated to side loads is difficult to understand. When thinking in terms of weave, wobble and chatter, there are a couple of apparent correlations. A more flexible frame seems to have a greater tendency to weave when cornering hard on a high-traction surface. Regardless of frame stiffness, chatter can be a problem just before the transition to side-slip. (It can be helpful to think of chatter as a forbidden zone between traction and sliding, avoidable by decisive control input.) Both weave and chatter during cornering are related to wheels not staying in plane, frequency and amplitude distinguishing one from the other. It makes sense that those problems are not due to side load as experienced by, for example, a car. But, when cornering, a frame is not under a purely vertical load either, as the contact patch is offset from the centerline. Both weave and chatter as described above involve torsional frame flex. If the cause is neither side load nor vertical load, what is it?

    • You are right, there are sideloads on the frame as you corner, and especially as you countersteer to initiate a lean. But these sideforces are relatively small compared to the loads the frame experience when you pedal. Thus, it seems that all frames are stiff enough to resist those loads sufficiently, and there is no difference in handling between stiffer and less stiff frames. That matches our observation in the double-blind test of frame stiffness, where two of us easily could tell the frames apart when sprinting and climbing, but not at all when descending.

  2. John Clay says:

    It seems like .9/.6/.9 wall in conventional diameters, possibly with an 858 or 747 top tube, would provide a useful range of flexural characteristics, including accommodation of a broad range of increasingly large riders, while providing dent resistance nearer the “better” end of the spectrum. Why the the jump into OS tubes rather than more fully utilizing the capabilities within conventional diameters?

    • The torsional stiffness of a standard-diameter .9/.6/.9 mm tube is roughly the same as that of our Oversize tubeset, but the Oversize is significantly lighter. With that in mind, we chose to invest in the tooling for the OS tubes.

      On larger frames, you can also increase the frame stiffness by using the ‘short’ tubes we offer. The length is almost the same, just the ultra-thinwall ‘bellies’ are shorter, which means that the tubes are stiffer.

  3. canamsteve says:

    Interesting that you do not ever mention the actual diameter of the tubes used. Is that because they vary depending on frame sizes? While wall thickness and butting are of course important (some say denting can be a risk with thinner wall sections) it would seem that “oversize” can mean quite a range of sizes – and even then that is in reference to some norm (traditionally 25.4 TT and 28.6 DT)?

    • The diameter is marked in the tubing specs, but it’s pretty simple: ‘Standard’ refers to a 1″ top tube and 1 1/8″ down tube. ‘Oversize’ is 1 1/8″ top tube and 1 1/4″ down tube. Seat tubes are always 1 1/8″ (so that a 27.2 mm seatpost fits inside…)

      There are larger tubes, but we don’t offer them, as they just get too stiff for most riders.

  4. aquilaaudax1 says:

    Would you recommend this tubeset for a classic road race, 700c, frame that’s going to be used by a 78 kg rider on longer rides with plenty of climbing and dirt roads? Or would I be better of using something like standard diametre Reynolds 853 or 631?

    • Many great bikes have been built from these tubes, especially for taller riders. It really depends on your preferences and riding style. If you mash bigger gears, a stiffer frame may be better. If you spin, a more flexible one often allows you to get more out of your pedal stroke… Personally, I prefer the ‘Superlight’ and ‘Mule’ tubesets, but then, my weight is closer to 70 kg.

  5. Matthew J says:

    Having bought more than ten custom bikes over the years, it’s been my experience anyway builders can get prickly when customers come to them with proposed tubesets.

    Keeping a list of builders who have already made frames with your tubesets or have expressed interest in doing so may prove helpful to both prospective customer and builder. Gates for instance does this now.

    • Kaisei tubing has an excellent reputation, and I can’t think of a single builder who would reject it – except for those who’ve developed a proprietary tubeset that they use on all their bikes. So if we made that list, it would include most framebuilders.

      However, the selection of the actual tubes (diameter, wall thickness, butting profiles) is something that should be done by the builder. You are absolutely right, if you went to a builder and say “I want a frame built from Kaisei ‘Oversize’ tubing,” the builder probably would (and should!) say: “Not so fast! Let’s look at you riding, at your current bikes, at the rides you intend to do on your new bike, and then talk about the tubing.” So that process should be a collaboration, where the customer asks questions and (perhaps) makes suggestions, but in the end trusts the builder.

      If builder and customer believe in different philosophies (say, one believes that ‘stiffer is better,’ while the other is interested in ‘planing’), then it’s usually better to find a builder who is on the same page than trying to convince a builder to make a bike they don’t believe in.

      • Matthew J says:

        I understand and respect what you are saying in the second paragraph. In fact perhaps not so eloquently it is the same advice I have given first time custom buyers who have come to me with questions based on how many customs I’ve bought over the years.

        Unfortunately ‘I’m just real curious to experience what Jan has written about so much on his blog and in BQ’ does not translate well to most reputable steel frame builders.

        The rub with high end steel frames is you go custom or you don’t go at all. I can and have walked into an LBS and gotten a formidable CF race frame and even a pretty good semi-custom Ti frame. Rode them long enough to learn they weren’t for me then donated them to local charity auctions. Would be something if there were the same sort of option for your light weight tube sets. Fantasy, I know.

      • I agree that a readily available high-performance steel bike would be great. As you say, walking into a bike shop and being able to test one would go a long way to dispelling the myths that ‘steel bikes are heavy’ and ‘steel bikes are slow.’

  6. Double oversize/OOS (31.8mm/1.25in TT and 34.9mm/1.375in DT) deserve a mention for frames above 58cm and even larger. While I am fully on board with the concept of planing and that everything these days is way too stiff for performance (among other geometry limitations), tall cyclists have been excluded from all considerations and that includes by the bicycle industry as a whole. Saying that made to measure frames were an eye-opener would be an understatement. I have two OOS steel frames (61-62cm top-tubes; one built for me and one by me) coming soon and I am defintely curious how will they ride since I designed them before I could fully wrap my head around the planing concept.

    Just as a sidenote is that when you mention such ‘size recommendtaions’ it is nice to include a bit more numbers on the riders because 150lb rider (such as yourself) on 55cm top-tube frames (even oversize) is VERY different than somebody who weighs 180lbs (and much more) riding 58+cm top-tube frames. You do mention in the comments that all of your expereinces are what works *for you*, though you cannot exclude a solution that is a game changer for a good number of cyclists out there.=)

    Even if you don’t offer them directly, mentioning OOS would paint a more complete picture on what is available.

    • You make some interesting points. When we did the double-blind test of frame stiffness, we used frames that were 58 cm tall, with 57 cm top tubes. We were surprised that even during uphill sprints with 600 Watts or more, the ‘Superlight’ frame didn’t flex excessively. Sure, we are not very heavy, but that power output isn’t something most cyclists reach on a daily basis. So even for relatively tall and strong riders, even the lightest tubesets can work well. The ‘Oversize’ tubeset already is quite a bit stiffer, and I’d recommend it for larger bikes, too.

      If a rider needs a 70 cm frame or so, then that is a totally different matter, and few tubes are long enough for those anyhow! For the few riders that tall, it is indeed a difficult situation – usually, straight-gauge aircraft tubes are used, since there is no need for butted tubes when you are trying to get more stiffness and strength anyhow. (Butting is used so you can make the centers of the tubes thinner, while keeping the ends thick enough to make strong joints.)

      • The ‘challenge’ when it comes to large frames is that longer tubes are significantly less stiff and taller riders are usually (much) heavier and have wider handlebars etc so just regular riding torques a frame more. Size 70 frame is big outlier (Shawn Bradley for example) and while tubing exists in 9/6/9 butting it is indeed rare and maybe even OOS might not be strong enough and you might need rollcage stuff. In my n=1 experience stock frames are too twisty under (hard) cornering and sprinting and i am not that big at 6’7″/185lbs, getting a custom titanium frame made me realize how a bike should actually feel and handle.I will definitely read the full test you made, since your blog posts for sure sparked my interest and ‘planing’ makes perfect sense. I am eager to try the two OOS steel frames i have and how they fare in terms of stiffness and now i have an idea on what to look for in a frame. Maybe i will find that just Oversize is enough. As you know yourself – we all have our (two wheeled) journeys of discovery.=)

        It is nice to find a place where cycling ‘traditions’ get questioned. You article on front end geometry and the merits of larger tyres has made me reconsider quite some of my framebuilding projects. Keep up the good work!

  7. John Clay says:

    I drafted a spreadsheet that calculates the stiffness of different tubes based on their dimensions. The output is a ranking of tubes by relative flexibility. With the help of others it’s being verified and improved for use as an aid to tube selection. You can see the initial, non-peer reviewed, results here: https://groups.google.com/forum/#!topic/framebuilders/QaOg8c-17eE

    Updates and corrections will be posted within that thread as they are available.

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