tiagra and above groupset with dropbar

click here
https://forum.lowyat.net/index.php?showtopi...&#entry98863638

i am not sure about campagnolo…

but of course you can use shimano from tourney to ultegra. foldies mostly using rb parts.

foldies we just dump whatever parts that's working best for the wheel size. does this explain to your question?

chainring u might need to change the whole crankset since foldies normally using 130bcd. 52/39 or 52/42 is common for 20-incher.

cassette wise some of here even using custom 11-18t…but mostly 11-28t, 11-25t, 11-32t, 11-36t depends on your terrain, wheel size, single or double chainrings setup too.

RD if 16-incher must use short-cage.

FD no need worry…plenty of mod parts even if your frame don't have the FD mount.

shifter just need to check the compatibility to your RD.

are you come from rb and need a smaller bike to travel around?

d9 is using hydraulic disc brake right?

why not just get the tern verge p9 and save all the time and hassle to mod? If you can afford, look at Tern BYB S11, smaller footprint.

if u want road bike feel…better look for Pacific Reach.

but seriously…when you compare 451 with 700c rb, u will feel the size not much compact…better just ride rb. expectation vs reality is cruel. that's why many people bought bigger size folding bike eventually go back to rb. when you are having a folding bike that is not compact enough for portable, and it's not as fast as road bike, then you know what i mean.

my personal ideal size for folding bike:
1. Exocet Flying Fish with 406 wheelset
2. Fnhon Zephyr with 349 wheelset
3. Brompton or Pikes with 349 wheelset
4. Dahon K3 with 305 wheelset mod (3 speed 41T : 9-1317T)
6. Fnhon Breeze with 254 wheelset with schwalbe big apple tyre (single speed 41T : 9T)

Why not both?

I have both RB and foldie. Actually the foldie is my wife's, but she hardly rides it anymore, so I kinda took over riding it. Spent some money changing some parts and now I have 2 bikes to alternate with

not sure about modding groupset but the Altus came stock on the foldie. i only changed the cassette ratio to 11-32 from 11-28 but maintaining 8-speed.  but not long after the shifter went bonkers and considering the cassette still new i bought another 8-speed shifter.

on hindsight i should have gone with a 9-speed shifter and swap to a 11-32 9 speed cassette, one extra gear so lesser jump between gear shift. The RD can support so it doesnt need to be changed.

Current stock crank is a 52/42, i have another 53/39 ready on hand. smaller small crank should allow me to climb easier. but havent have the time or need to get it swapped yet

based on your requirements

105 groupset la

50/34T

11-30T

You have that much of a budget I know of one guy letting go of his newly assembled fnhon with ultegra groupset. Not sure if he sold it off yet or not