I took that new SILCA Terra pump and did a couple of tire swaps the other day. First up was to switch the WTB Vulpine S tires to another wheel set. I decided on the DT Swiss hubbed Roval wheels I have.
These are mountain bike wheels, they have six bolt rotor interface, and convertible axle interface, and are narrow. I think the internal width is something like 21mm? I cannot recall, but it is skinny.
The Vulpine S tires are 45mm wide and they look great on these rims. As in they set up well and look fine, as far as how they should perform goes. Aesthetically? Well, this scheme on the rims is a little "shouty", and that really isn't in vogue these days. But the Rovals are probably 12 years old. So times have changed.
One thing is certain, not only are the graphics out of date, but the inner rim width is as well. However; as with most trends, I feel the "wider is better" trend is going to pull back some from the extremes it is reaching for now. Maybe things won't go back to 21mm inner rim width, but I can see 23mm - 25mm being a "sweet spot" where inner rim widths for road and gravel will eventually settle into.
I don't think I am wrong because if you look at how light wider rims are now for gravel, just think how light they could be using less material in a narrower rim. The performance won't suffer, and 42mm -45mm tires will be just fine in the inner rim width range. There are no downsides. I know tire sizes are reaching toward 50mm+ on gravel bikes the racers use, but I think even this trend will pull back for similar reasons. Lighter, more aero, and easier to attain mud clearances.
But I digress...
The tire swaps will encourage more riding, allow me to get some more review stuff done and buttoned up, and keep me riding. All good things.
A Success Story:
The Honeman Flyer by King Fabrications based upon a 1930's track bike design has become something of an obsession with me. I am constantly reaching for this bike even just to go around the block once if that is all the time I have.
I did not expect this to happen. The radically slack seat angle and long chain stays are laughable on paper. No one would choose this for their bicycle in 2024.
But perhaps they should consider this.
I'm not going to sit here and claim that this is "the next big thing" but I've never ridden a bicycle that handles like this one does. Well.....maybe my old 20" banana seat bike did. I recall that bike being really stable, but think about what the effective seat angle is on a bicycle with a long, 'banana' style saddle. Pretty slack, I bet.
So, maybe that is where I developed an affinity for the set up on the Honeman Flyer. Or, perhaps, those old builders were on to something in the 1930's. I mean, they weren't doing this to make the bicycles slower, or less racy. This design won a track championship, so it isn't like it was some cruiser meant for recreational riding.
All I know is that, while the design might be crazy, I love it. This has been the most fun bicycle to ride that I have owned since I got the Gen I Fargo in late 2008. I just cannot seem to stop wanting to ride it. So, for me the Honeman Flyer is a success.
I think chainstay length is not quite the right metric for judging how a bike will ride, at least if seat tube angle is not the same across bikes you’re comparing. It’s better to think of it in terms of horizontal distance from your center of mass to the bottom bracket. The slack seat tube causes the bottom bracket to move forward (unless the seat tube is bent). This means your center of mass is likely over or just behind the bottom bracket. Of course, this distance is very dependent on saddle position and upper body position. So it’s not a frame dimension. But it’s good to think of seat tube able and chainstay length as intimately related and that affects what makes a chainstay “long”. If the rear axle still ends up close to your butt, then I would say it’s “short”. So I would judge your Honneman Flyer as riding as if the chainstays are short.
ReplyDeleteThere’s something magic about having your weight centered at the BB (or slightly behind). It’s one of the stiffest parts of the frame, so that extra weight there will soften the ride a bit. It makes the bike ride beautifully because your weight is being applied to the lowest point on the frame, below the axles, so the bike reacts more to your body side to side movement. That makes it better at both holding a line and carving a turn (assuming you lean your body). Less weight on the front wheel helps it roll over bumps better. The one downside is needing to put a bit more weight in the front wheel in loose corners.
Then there’s benefits of the slack seat tube. Up hills it puts your weight closer to the rear tire contact patch for better traction. Down hills your weight is also further back. The longer and angled back seat tube and post absorb bumps better because the force is more bending the tubes instead of going more through the tube centerline.
So yeah, there’s a lot to like about slack seat tubes, weight over/behind the BB and rear axle under your butt.
@Nooge - This comment: "There’s something magic about having your weight centered at the BB (or slightly behind)" is the one that I think is what describes what is going on here the most succinctly. I felt this the moment I threw a leg over the bike to do the first test ride.
DeleteThis is in direct contrast to most bicycles I've ridden which are "weight forward" in design and do no center the bulk of a rider's weight evenly between the axles. It is less comfortable for several reasons.
Perhaps the 1930's designs were driven by the needs of the previous generation of six day racers. Combined with the fact that many of these bikes were also training bikes over rough roads, the geometry was, perhaps, driven by needs of stability and comfort for the rider.
It would be a great read to find any book or discussion recorded concerning this with fellows like "Pop" Brennan, who was one of the premier designers and builders of track bikes in the 1920's - 1930's. To get into the reasons why they chose the designs they chose would maybe help explain what I am feeling now, almost a 100 years later!
I have had very similar experiences to yours concerning seat tubes and chainstay length.
ReplyDeleteMy first experience was with a Jones LWB. I bought it inexpensively, expecting to sell it. The bike rides wonderfully! It handles great on the road and off-road. One of my favorites.
The second was a Rivendell Appaloosa. I think the seat tube is 71 degrees with incredibly long chainstays. I can't believe how stable this bike rides and absolutely carves descents.
On both bikes, I feel very comfortable. You don't know what you don't know.
I’d love to be able to experiment with slacker seat tube angles, but bio mechanically it simply doesn’t work for my legs. I do however typically like bikes with a bit longer chainstays.
ReplyDeleteThe long chainstay and slack STA do sort of cancel each other out, and this makes short cranks work even better. I've built a couple frames exploring this, and recently blogged my current gravel bike with a 71 STA and 465mm stays for 155mm cranks. https://drwelby.net/bikewrites/bike-check-sc-3/
ReplyDeleteI really enjoy your writings Marc. Your experiments are thought provoking and actually pushed me to try the Rivendell. I am currently running 160mm cranks on the Riv with a 25mm offset post and the SMP saddle slid quite aways back. I have so much power and is very comfortable for moderate to high power output for long durations. Keep up the experiments and blogging.
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