Lightcarbon: New LCR017-D (or Yishun R1058-D)

[Serge_K]

Since I'm a cyclist and not an aerospace engineer, I don’t have access to a wind tunnel to measure these things. What I can say is that my bike performs perfectly in all situations, even on descents at 80 km/h. I've never noticed any weird noises or whistles like the ones you get from roof racks on cars, so as far as I’m concerned, the square downtube isn’t a real issue at all.

The drag would have to be insane for you to be able to hear it.
A bus isn't aero. Therefore, that downtube can't be aero. Would you be faster on a kamm tail shaped down tube? almost certainly. Would you EVER see a bus shaped downtube on a TT bike? No. Do you see kamm tail shaped downtubes on TT bikes? Pretty much 100% of the time.

Now, does it matter?
If you like your bike, great.
From my perspective, most of my riding is done on the flat, so i do care if i can save 5w at 40kmh, because i often ride at 40kmh.
And from the perspective of people considering the frame, they should know that this feature can't possibly be fast. Whether it matters to them or not, is for them to decide.

My frame arrived today and all my worries about quality issues faded 
Frame is a top notch without any wringles, cheese and etc.

Lovely bike!

[ceres]

The drag would have to be insane for you to be able to hear it.
A bus isn't aero. Therefore, that downtube can't be aero. Would you be faster on a kamm tail shaped down tube? almost certainly. Would you EVER see a bus shaped downtube on a TT bike? No. Do you see kamm tail shaped downtubes on TT bikes? Pretty much 100% of the time.

Now, does it matter?
If you like your bike, great.
From my perspective, most of my riding is done on the flat, so i do care if i can save 5w at 40kmh, because i often ride at 40kmh.
And from the perspective of people considering the frame, they should know that this feature can't possibly be fast. Whether it matters to them or not, is for them to decide.
Lovely bike!

Easy, just don't buy It   

[rasch]

I'm a bit surprised no one else has reported this issue before. I’ve already contacted Lightcarbon, and they just said it’s normal, but I’ve never seen anything like this on other bikes.

Yessss. I have it too. It's super annoying. I had a puncture last ride and it took me forever to get the thru axle aligned with the wheel.

Is quite annoying

[edy]

My frame arrived today and all my worries about quality issues faded 
Frame is a top notch without any wringles, cheese and etc.

That black and tan tire combo is mint!

[Walter-sobchak]

Has anyone out in the real world been able to quantify whether or not the square downtube is actually causing significant drag? Meaning, does the riding dynamics on road feel draggy? Can you actually tell?

I spent a significant amount of time riding side by side with friends on flat terrain, and as someone who pays close attention to power data, I feel confident that this bike doesn't come with an aero penalty. Based on what I've read about aerodynamics, the downtube is positioned in the 'dirty air' created by the front wheel, so having a slightly less aerodynamic shape doesn’t significantly impact performance.

[ceres]

I spent a significant amount of time riding side by side with friends on flat terrain, and as someone who pays close attention to power data, I feel confident that this bike doesn't come with an aero penalty. Based on what I've read about aerodynamics, the downtube is positioned in the 'dirty air' created by the front wheel, so having a slightly less aerodynamic shape doesn’t significantly impact performance.

I would also add that the biggest impact on aerodynamics comes from the cyclist and their position on the bike. However, it's true that I was looking for a stiff and lightweight frame, easy to handle on climbs. That said, with this bike, I’ve improved many of my personal records, even on flat terrain.

[Da11as]

I own a 2018 BMC Roadmachine size 54 and a 2011 Kuota Karma. There is no comparison with the Kuota, whereas compared to the BMC, I can say that, in terms of ride quality, I haven't noticed any significant differences. In fact, I actually prefer the LCR017 because I built it to fit my measurements. The geometry has a slightly longer reach and a lower stack. Surprisingly, I feel more comfortable with the lower stack, which is about 3 cm lower. As for the reach, I compensated by shortening the stem.

The frame I received is of excellent quality, and the assembly went smoothly. The BB on the LCR017 is a T47-68 mm, which threads into the frame and is easy to handle, whereas the BB on the frame you're proposing is a press-fit type, which is a bit trickier to deal with.

I wouldn’t underestimate the issue with the rear hanger. If you do races and need to change wheels quickly, I think it's better to avoid the LC frame. Otherwise, the issue is almost negligible, though personally, it does bother me a bit.

Yeah, that is clear. I am more about the ride quality, given you have same (or very similar) wheel setup.

[Da11as]

The drag would have to be insane for you to be able to hear it.
A bus isn't aero. Therefore, that downtube can't be aero. Would you be faster on a kamm tail shaped down tube? almost certainly. Would you EVER see a bus shaped downtube on a TT bike? No. Do you see kamm tail shaped downtubes on TT bikes? Pretty much 100% of the time.

Now, does it matter?
If you like your bike, great.
From my perspective, most of my riding is done on the flat, so i do care if i can save 5w at 40kmh, because i often ride at 40kmh.
And from the perspective of people considering the frame, they should know that this feature can't possibly be fast. Whether it matters to them or not, is for them to decide.
Lovely bike!

Quite many modern allrounder bikes have square shaped downtubes, Giant or Bianchi, for instance. It's not much a deal from perfomance perspective. But it indeed hurts my eyes...