tdong

Currently i have Alfine 11 with 18T rear and 52T front on the 20" wheel dahon. what front and rear combine would give me around 32T and 34T on a normal road bike 700cc.

I can't climb steep hill with my fold but I can do it with my road

1nterceptor

Smaller chainring(less than 52T). That' what I did with a BF Pakit I just got.
Swapped the 53T to a 44T I had laying around. I think I went too far. Will swap
again with a 50T I also have laying around.

tdong

thanks will give it a try with a small front. i have a 42 laying around will try that first

tdonline

When changing chainring size, do you also have to change the chain length?

Same story here, I can't go up hills on my Dahon D7 like I can on my road bike. Have been contemplating cheap/easy solutions.

reppans

Yes, usually by 1/2 the difference in teeth (since the chain only engages 1/2 the chainring).

tdonline

Thanks Reppan. After posting, I searched for a local bike co-op--it really is time for me to learn how to take care of my bikes! Found one not so local but still within 45 minutes of ride time. I sent an email to inquire about their beginner's workshop--hoping they have something in the fall.

invisiblehand

Your current Dahon has direct drive gearing proportional to ... 20 * 52 / 18 ~ 58
Your 700c road bike has gearing ... 27 * 34 / 32 ~ 27

Your Alfine's gearing ... https://www.sheldonbrown.com/alfine-11.html

The lowest Alfine gear is 0.527. Right now the lowest gear on your Dahon is ~31 gear inches. (27/31) * 52 ~ 45 is the chainring size you're looking for.

42 is a safe bet assuming you care about the bottom end more.

tdong

Thanks for a detail answer.

tdong

My bike is like a single speed to due internal gear. I already have the chain tension no need to cut anything

tdong

my 42 chainring doesn't fit my front (130 i think my front is 110). can i get the 23T sprocket and assuming 1 teeth at the back should be double at the front.

badmother

sounds right

invisiblehand

If you change the chainring/cogs by several teeth, you'll probably need to change the chain length.

Leisesturm

What just about everyone in this thread is missing is that your 700C road bike usually has two (2) chainrings! One a 52 and the other a 42 or something like that. Change the only ring on the folder to a 42 and you will go up the hills alright, but you will be miserable at any other time as senior citizens call "on your left" at you as you flail away. My folder has a 53 ring and it doesn't go quite low enough so I walk up the steepest hills, for now. At least this one has round tubing, my earlier one did not. I can put a front derailleur on this one if I get annoyed enough. Either that or find a SRAM dual-drive hub. I've had a 45T ring on my old Giant 1/2way. I know what that feels like. Bleah. A 42? Just shoot me. Sorry to break it to you guys but what you want will be neither cheap nor all that easy. But it is possible. There is that...
'

Leisesturm

It does? I don't know, but I would not assume. Easy enough to calculate the gear inches with the present rear cog, and also any other cog to be considered. Then spend money.

Rick Imby

Great post Leiseturm--

It may not be just the gearing on the 700c, it may be a higher quality bike also.

A 30 pound cheap folder will not go up hills or have the top speed of a 20-23 pound 700c bike.

Add the lack of two chainwheels up front.

I have said it over and over in the folding bike forum---be sure to buy a bike with a cassette rear hub NOT a freewheel rear hub so you can get a much wider range cassette with 11 tooth small and 32 or 34 big. With small wheels and one chainring the cassette gearing benefit is huge.

badmother

When I am to lazy to calculate my rule of thumb is "two in the front equals one at the vback".

When I need to spend money I calculate. Most of the time I just dig into the shed and find what I need.

tdonline

I have a triple

Yes, Agree with all your points. It's a catch-22. If I go with a smaller chainring, I'll be a spinning fool for many rides.

tdong

$10 fix very happy



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