Brompton G Line (20" Gravel Bike)
09-21-24, 11:14 PM
#51
Actually, ETRTO507 is not so bad for the tire choice for wide touring tires, 50mm or more.
The error of Helix is that they limited the width to about 40mm.
And, like for the G-line, a bigger wheel diameter mean an bigger folded size (and also some weight increase). I guess that Helix choose a max width of 40mm to reduce the folded size, as already said, Helix is more a 23" wheel size bike than a 24" wheel size bike.
The question is also the real benefit of 24" vs. 20" with the same type of tires, does this 20% overall wheel size increase provide enough rolling improvement to justify the folded size increase and the increased inertia of the bigger wheel diameter?
For me having tried bikes with 24" and compared to 20" with same wide tires, I think that the 24" wheel size of Helix is only a marketing feature aimed at customers not used to small wheel size bike ( I remember very well the original Kickstarter campaign in which the creator claimed that Helix is safer due to its bigger wheels).
The error of Helix is that they limited the width to about 40mm.
And, like for the G-line, a bigger wheel diameter mean an bigger folded size (and also some weight increase). I guess that Helix choose a max width of 40mm to reduce the folded size, as already said, Helix is more a 23" wheel size bike than a 24" wheel size bike.
The question is also the real benefit of 24" vs. 20" with the same type of tires, does this 20% overall wheel size increase provide enough rolling improvement to justify the folded size increase and the increased inertia of the bigger wheel diameter?
For me having tried bikes with 24" and compared to 20" with same wide tires, I think that the 24" wheel size of Helix is only a marketing feature aimed at customers not used to small wheel size bike ( I remember very well the original Kickstarter campaign in which the creator claimed that Helix is safer due to its bigger wheels).
I would think if someone debuted excellent, larger 24" tires, Helix would tweak the design to use them, however, the total girth of the current model is 63.5" and 0.5" can be shaved by removing the seat and stashing it in the fold. That's awful close to legal checked bag size of 62", which is a big deal. So no, if they make a change I think it will be to 451 or 406 and clearance for up to 50mm at least.
EDIT: BTW, Helixes are spec'ed with 165mm crankarms.
Last edited by Duragrouch; 09-21-24 at 11:58 PM.
09-21-24, 11:27 PM
#52
Senior Member
Plenty on Lazada, here. (and Shoppee, Aliexpress, etc)
Cycle into any South East Asia bike shop (especially the mom and pops ones and they will surely have some kids bikes using 24")
As mentioned, these are 'replacements in a pinch' , not about latest and greatest tire options (of which there are for 24" as well )
Maybe its different where you are.
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09-21-24, 11:31 PM
#53
Senior Member
I think the decision for 24" was them looking at gear inches versus fast bikes. My 20" has a tall enough top gear (50x11x406) for me, I can pedal down mild grades, but it's no race bike. Given that the cassettes used on Helix, modern, I think have a 10T high cog, even better. (EDIT: Nope, 11T standard, 9T on premium lightweight model.) But then 24" also has market differentiation, it looks faster on paper, and like you said, a lot closer looking to 26"/559.
I would think if someone debuted excellent, larger 24" tires, Helix would tweak the design to use them, however, the total girth of the current model is 63.5" and 0.5" can be shaved by removing the seat and stashing it in the fold. That's awful close to legal checked bag size of 62", which is a big deal. So no, if they make a change I think it will be to 451 or 406 and clearance for up to 50mm at least.
I would think if someone debuted excellent, larger 24" tires, Helix would tweak the design to use them, however, the total girth of the current model is 63.5" and 0.5" can be shaved by removing the seat and stashing it in the fold. That's awful close to legal checked bag size of 62", which is a big deal. So no, if they make a change I think it will be to 451 or 406 and clearance for up to 50mm at least.
https://www.modernbike.com/tires+tir...meterequals507
There are enough good tires for 24"
Personally, I'd worry more about the special Helix hub and my own fitness and budget for good tires than tire options.
09-21-24, 11:35 PM
#54
Senior Member
Before this post and the G-line in particular peaked my curiosity, I have not looked closely at 20" trifold bikes, thinking of them as some sort of frakenbike done up by enthusiasts.
But seems like the option of such bikes have existed for a while now.
Even though this guy sells the bikes, I think he's quite enthusiastic about it and gives a better overview of the bike than the what GCN has done for the G-line.
But seems like the option of such bikes have existed for a while now.
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09-22-24, 12:02 AM
#55
https://www.modernbike.com/tires+tir...meterequals507
There are enough good tires for 24"
Personally, I'd worry more about the special Helix hub and my own fitness and budget for good tires than tire options.
There are enough good tires for 24"
Personally, I'd worry more about the special Helix hub and my own fitness and budget for good tires than tire options.
Helix actually specs the outside diameter at 23", and I think that is essential for the fold.
The hub is spec'ed as "Formula Helix". Sounds like made for them by Formula (I only have experience with their cheaper hubs). It's a cantilevered hub, but there might not be much special to the hub, just the axle being essentially a bolt. The hub itself doesn't know if it's being supported in double shear or cantilevered.
09-22-24, 08:46 AM
#56
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I'm unconvinced that the classic Andrew Ritchie trifold design that works so well at 16" is optimum for 20". The Caracle trifold design (with 20" wheels) and Tern BYB trifold design (with 20" wheels) both fold appreciably smaller.
09-22-24, 02:39 PM
#57
Senior Member
https://www.modernbike.com/tires+tir...meterequals507
There are enough good tires for 24"
Personally, I'd worry more about the special Helix hub and my own fitness and budget for good tires than tire options.
There are enough good tires for 24"
Personally, I'd worry more about the special Helix hub and my own fitness and budget for good tires than tire options.
Increasing a lot the wheel diameter to 54x406 require a new folding concept.
But Brompton is captive of his marketing image, a Brompton with a fully new folding concept would not be a Brompton anymore.
Last edited by Jipe; 09-22-24 at 02:52 PM.
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09-22-24, 04:38 PM
#58
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09-22-24, 05:31 PM
#59
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09-22-24, 06:09 PM
#60
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I personally think they did a pretty good job of it, but there are some caveats. It's cost prohibitive, which I'd expected it to be, it's strangely limited with its usage of an internally geared BOAT ANCHOR hub, its more massive than I'd imagined it would be, and it's BLOODYYY HEAVY for what it is. I'd either opt for a BrompNot, or just go with a tried & true, easily serviceable dual folder. I like it, but I'm disappointed at the same time.
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