YonathanZ

Hi,

I'm looking for the cheapest way to add suspension to my 20 inch folding bike. This is my bike:


As you can see, the place where the seatpost enters the bikeframe (not sure what it's called) is low, like on dahon and tern frames, which is a problem because I cannot find a suspension seatpost that's long enough (the one I got with the bike is 450mm, and I have it fully extended).

I already replaced the saddle and it helped a lot, but I could use a bit more suspension. The tires are 1.5 inches wide and the rims only allow for tires up to 1.75 inches wide, and since it's an ebike I don't want to deal with replacing the rims as well (rebuilding the wheel with the hub motor is expensive).

Is there a way to extend the seatpost? How about an entirely different solution (that you might know about...)?

HGR3inOK

Where are you located? This is a worldwide forum. Options will vary among locations depending on price and availability. Also, what is your seat post diameter? This value is probably stamped on the seat post. I believe the current Dahon suspension seat post is 39.9 mm.

-HANK RYAN-
Norman, Oklahoma USA

downtube

Look at a triathlon setback adapter to push your saddle up and back.

I don't like suspension seatposts. Your leg length will change as it engages. Hence I prefer a suspension fork or balloon tires.

Thanks
Yan

1nterceptor

There are saddles with suspension(springs) built-in.
Fit the widest tires and use the lowest air pressure
without causing pinch flats.

ThorUSA

okidokee
check your seatpost diameter .. if it is 33.9 mm you are in luck ... 54 cm to 66 cm on the thudbuster lt will make leg extension a thing of the past ...
The regular suspension seatpost is really not that bad, especially not for the price it is sold. The thudbuster although almost 3 times as much get raves from everybody who got one ... the suspension goes in a arc, meaning the distance to pedals changes only minimal. Anyway, not a problem in my opinion unless you are a very sportive rider. ( With the bike you have I highly doubt that, and hence a minimal loss in "theoretical"performance doesn't matter. )
Next ... get some big apples .. 20 x 2.00 will definitely fit... with your generous room to the fenders even the 20 x 2.10 should be ok ...
easisiest and most likely cheapest mod u can do
I have the suntour suspension fork , which will fit in your bike .... as long as u get a 100 mm axle front wheel ..( maybe u have one already, most folders come with 74 mm front axle )

add a SUntour fork and a thudbuster, get some big apples,,, and your ride will be buttersmooth ... :-)

thor

YonathanZ

How can you be sure that 2" tires will fit? The guy at the bike shop (not the one where I purchased the bike) said he thinks the rim won't work with a tire fatter than 1.75" (I asked him while he was replacing the inner tube of the front wheel).

IIRC, the width for the seatpost is 30.9mm. A Thudbuster is too expensive anyway, and maybe even unnecessary if I can use those Big Apple tires. How are they at cornering, btw? I do use this bike for "sports", so to speak. Will they limit my ability to do sharp turns?

tds101 

Fat Schwalbe Big Apple tires are excellent on cornering. I used them on my REALLY sporty Xootr Swift. Excellent tires,...add some nice cushioning. I have Schwalbe's on my 29er now. I don't feel any bumps. I plan on putting them on all my bikes.

YonathanZ

Thank you, that's great to hear. Now I only need to find out if the rims on my bike can take a 2" tyre. How can I find that out for sure before I order those tires?

tds101 

The picture doesn't help. What brand is the bike?

fietsbob

Under Your Butt, suspension seat post, will be low cost . the ones at about $30 bucks are not as nice as the $200 ones . of course.

YonathanZ

It's an Italwin eLight. There are no specs whatsoever for the bike on the company's website.

jur

Can you make an estimate of the width of the rim? I would be very surprised if the rims this being an eBike couldn't accommodate Big Apples. The biggest problem is likely not the rims but the frame clearance.

tds101 

Their other bikes use 20X1.75 tires. See how much space is between the fork and tire, and on the back wheel as well. 2.0 tires just might fit.

I was told by a bike shop owner 700c and 29er tires were different - they're actually the same. Do a little digging and see what works.

fietsbob

So this is in advance speculation , you cannot even measure the fork width because you are not in the same room with the product ?
eLight? Ha!
Its got a Motor and a Battery .. they aint Light .. a Dahon knock off copy apparently .. the most copied folding design Made. in China..

osco53

ThudBuster... They show a 610 mm post,,,

Tuneable

Welcome to Thudbuster.com

From my recumbent experience and now my Dahon a 20 x 1.75" handles sidewalk cracks noticeably better than 20 X 1.5"

And from my mountain bike experience narrow rims and larger tires only squirm a little more at the upper levels of performance.

I'd put 2" wide on my current Dahon's rims with no worries at all.. I cannot Imagine your rims are narrower..

YonathanZ

The frame and fork can probably even accommodate even a 2.35 inch tire by the looks of it. How can I measure the internal rim, though?

bhkyte

I found a range of koga extending telescopic seat posts available on ebay. These were intended for folding bike. I simply bought one that matched my bike frame diameter then replaced the inner with a standard suspension seatpost.

This cost about 30 pounds. I added this to my mezzo, as and ocassional option. It's very long and I don't need to extend the inner seatpost at all. Only disadvantage is it results in a larger fold as the post does not fully insert. I can always remove it if it's an issue on a commute or car journey.

YonathanZ

That's a clever idea. I'll continue researching the option to replace the tires with Big Apples, but if that doesn't work out, I'll get that KOGA seatpost + an XLC suspension seatpost.

ThorUSA

I really haven't seen a rim which is used today which would not accommodate big apples .... that rim would be super super narrow and most likely very expensive .. way to expensive to put on a bike like yours .

I love bike shop guys who talk out of their ........ Makes my life soo much easier ..lol
Nothing wrong with bike shops in general .. there are some places where it is a pleasure to walk in.
thor

p.s. in the past Thudbuster only made the 33.9 in a very long size
but that can change over night

osco53

Yank a tire off..

My mountain bike with 2.35 wide tires has rims at 24mm O.D. and Inside Diameter is 20mm

My Dahon's Outside Diameter is 20 mm, so I'm guestimating I.D. would be 16mm,, yeah If I needed wider I'd go 2.0 Apples..

YonathanZ

OK, I took measurements for the frame to see if a 2" or even 2.15/2.25" tire would fit.
So here's how much space there is between the current tire (1.5") and the frame:

fork: left side of wheel - 15mm. right side of wheel - 10mm.
back wheel, lower part of the frame (whatever it's called): left side of wheel - 11mm. right side of wheel - 15mm.
the top part of the frame, near the rear wheel, has tons of room, so I didn't bother measuring.

So I guess I should be able to fit the 2" big apples, right? As long as the rim is decent, of course.

tds101 

The rims aren't an issue. On this type of your not getting super thin racing rims. The tires will fit regardless. Take the wheel off the bike, take a ruler, measure the gap in the fork and frame where the tires fit. That will show you how much clearance you have. TAKE THE WHEELS OFF TO BIKE FIRST!

YonathanZ

I measured without taking the wheel off, but I'll see if I have the tools.

Update: Took the front wheel off, measured 2.75 inches the lowest, and another time it was 2.81 (I used that tool, and it wasn't stretched tight because I didn't wanna scratch the fork, so it's probably even a little bit more than 2.8).

I've completely deflated the tire of the front wheel but am having trouble exposing the rim completely for measurement. I did see a writing inside, though: 20 x 16. I guess 20 is the diameter of the wheel in inches, and 16 is the internal width of the rim in millimeters. I'll keep trying to get an accurate measurement anyway.

YonathanZ

Measurements of the rim:


Will a 2.15" tire fit?

tds101 

GoGo buy your Schwalbe's. You're good to go!!!