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Old 06-09-17, 02:04 PM   #1
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Shorter folding stem for Allen Sports "Downtown"

I just got my first folding bike, a cheap Allen Sports "Downtown".
Great price at 110.00 shipped for an aluminum frame. Took off most of the junk and put on drop bars, leather seat,
and the bike is weight around 23 pounds. It's only a one speed, and I didn't want to invest too much until I played with folding bikes for a while.

The main problem is that it is a one piece stem, that is 14 inches tall! from the head tube to center of bar. Great it you are 6 feet tall, or want to sit in a totally upright position, but being only 5'7", and riding usually 50 cm road bikes, I want a shorter stem. Either an adjustable length stem or one that is about 4 inches shorter. With the straight bar, I felt like a kid with "ape" bars on a gooseneck. The drops make it a bit more comfortable.

Not really familiar with the various options of folding stems. I see that the fancier versions of Allen bikes go for higher prices and some have adjustable stem length, but getting one is not going to be an option, probably due to liability.

I see other options from China, but they look like they have different attachments. Some use the original nut like the Dahon and the Allen clamp. a few look like they use a quill stem with binder that goes into the steering tube and then the allen clamp. Some look like they have double allen clamps.

So how do I determine What to get for this.
The picture shows what I see. An Allen bolt that goes into what? The instructions say that this bolt should be tightened down and yet have the fork spin free, so I assume that it is a fixed length to the head tube for free movement of the races.
Does the allen into a stem like a binder bolt like on the old quill stems. Is it more like a thread less setup?

Is there a standard on these that make them interchangeable?
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Old 06-09-17, 02:30 PM   #2
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It looks like your bike has a threadless headset, I am almost 100% certain based upon the slot in the lower hinge. Can you remove the handlebar post to confirm? If it is threadless, there will be one or two fasteners through the bottom section of the hinge that just need to be loosened, and one fastener that goes vertically into the star nut in the steerer tube that must be removed completely. If this is the case, there are lots of options (I have a bunch if you just want to cover the shipping).
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Old 06-09-17, 02:59 PM   #3
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OK, with you help.
The star nut would be the allen head? I loosened it already, but didn't want to entirely remove it until I have an idea of what it does. So it goes into the steering tube.
Then there is only ONE Allen screw at the slotted clamp. Undo that and pull it off?
If this is the procedure, I can do that take a photo and measure the steering tube for replacement.
Thanks!
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Old 06-09-17, 03:31 PM   #4
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Quote:
Originally Posted by HighValleyRanch View Post
OK, with you help.
The star nut would be the allen head? I loosened it already, but didn't want to entirely remove it until I have an idea of what it does. So it goes into the steering tube.
Then there is only ONE Allen screw at the slotted clamp. Undo that and pull it off?
If this is the procedure, I can do that take a photo and measure the steering tube for replacement.
Thanks!
The start not is actually down inside the steer tube to have to undo that fastener and remove it completely Italy obvious one of us come out of the nut. The one on the side you simply need to loosen a little bit and then the whole thing will come off
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Old 06-09-17, 04:25 PM   #5
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I think Pingis wanted to say that the star nut is actually down innside the steerer tube.

That screw you are talking about in the center is screwed into the starnut (to keep it all in place). Undo it completely and then loosen the screw on the side of the lower part of the stem. Then you should be able to pull it off- I think...
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Old 06-09-17, 04:31 PM   #6
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Double tap

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Old 06-09-17, 04:38 PM   #7
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If the handlepost is made out of steel...you could do some metal fabrication to lower the handlebars.
Good point. Steel is easy to work.
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Old 06-09-17, 04:44 PM   #8
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Ok, thanks for all of your help. Disassemble it entirely and got it all back together.
The Allen bolt goes into the threaded portion of the steering tube. The purpose of this Allen bolt is both to secure it to the steering tube and fork, and also control the tension of the headset races.
The Allen bolt on the side of the clamp allows adjustment of the alignment of the stem to fork, and also secures the attachment of the folding stem to the steering tube. The tension of this allen head screw is quite snug. By removing the Allen bolt that goes into the star nut entirely, and loosening the Allen screw on the clamp, you can remove the folding stem.

>>>But while the folding stem was off, I wanted to see if the fork and steering tube can be pulled out and it came apart, but the top race, race retainer and cone all flew onto the floor. I was able to figure how it all reassembles!LOL. So it appears that the bottom of the folding stem rides on the plastic headset to keep proper tension.

The steering tube is 1 1/8" and the folding stem has a recess that slides over the portion of the steering tube that sticks above the headset.
1. The first photo shows the folding stem removed and the portion of the steering tube that pokes up from the headset. The Allen bolt goes into that hole in the center
2. The center photo shows the bottom of the folding stem. That recess is 24.14 mm and I assume that is a critical measurement as the bottom of that rides on the headset. Not sure if that was deeper if you can just back the Allen bolt out with the same results. SO I NEED TO KNOW HOW CRITICAL IS THAT RECESS FOR MATCHING??
The recess slides over the 1 1/8 tube so I assume that is another critical measurement in matching another stem.
3. The right photo shows the top of the folding stem, and the Allen bolt has a wide washer that is larger than that hold.
It is just flat with a flat washer. The other hinged portion of the folding stem is hollow, so it rides over the Allen bolt.
None of this looks to be as critical in measurements.
4. The OEM folding stem/post is alloy, not steel, so it just can't be cut and welded.
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Old 06-09-17, 04:46 PM   #9
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I have the exact same problem with my Boardwalk...and have ponder over it for many sleepless nights.

The trouble is these bikes are really designed for riding up-right posture.

If you lower the handlebar by 4"...you may have to also move it forward, to be comfortable...if you ride for long distance, or else be cramped.

I don't know if it's possible...without spending awful lot of money...and your bike may not fold properly afterward.

Quote:
Originally Posted by HighValleyRanch View Post
The main problem is that it is a one piece stem, that is 14 inches tall! from the head tube to center of bar. Great it you are 6 feet tall, or want to sit in a totally upright position, but being only 5'7", and riding usually 50 cm road bikes, I want a shorter stem. Either an adjustable length stem or one that is about 4 inches shorter. With the straight bar, I felt like a kid with "ape" bars on a gooseneck. The drops make it a bit more comfortable.

Last edited by mtb_addict; 06-09-17 at 04:55 PM.
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Old 06-09-17, 04:56 PM   #10
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mtb addict,
Being fairy short waisted, I usually go with a short top tube on my road bikes, and with the drops placing the hands in a more forward position, this might not be as big a problem for me.
Also there is a stem called the "lite pro" stem that also moves the handlebar a couple of inches forward. That and the more forward position of the drops could easily add four inches forward.
Since I'm new here, I can't link to an URL, but google litepro stem and you will see what I am talking about.
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Old 06-09-17, 05:11 PM   #11
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Quote:
Originally Posted by mtb_addict View Post
If the handlepost is made out of steel...you could do some metal fabrication to lower the handlebars.
Good point. Steel is easy to work.
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Old 06-09-17, 09:30 PM   #12
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Here is how it looks right now with the drop bars and original folding stem.
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Old 06-09-17, 09:36 PM   #13
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Front view. Just an vintage alloy Japanese drop bar from my parts bin, some drilled diacompe levers, and old ideal seat. Didn't have any bar tape on hand, so that is vet wrap!LOL
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Old 06-10-17, 12:43 AM   #14
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That already looks really great! Good frame color. Celeste. ☺️
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Old 06-10-17, 02:05 PM   #15
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I tried to contact Allen Sports to see if they could sell me an adjustable one, and they responded no.
"Thank you for reaching out on this. Unfortunately, we do not have an adjustable stem option available that will fit the Downtown model.

Best regards,

Allen Sports Customer Service
customerservice@allenracks.com"
========================

I searched on Ebay, but most all of the ones they are selling have a stem with binder bolt that goes into a hollow steering tube. I could not find any that looked like mine that slips over a 1 1/8 tube.
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Old 06-11-17, 03:31 PM   #16
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Put an old MB Blackburn rack I had around and modified it to fit for now.
For those who wonder if putting on drop bars affect the folding size, here is a photo of the bike folded.
Not by much if any, because you can rotate the bars over the wheel, and it ends up being the same position as the original flat bars.
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Old 06-13-17, 08:22 AM   #17
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Wow!!! Incredible...I've been thinking of doing something similar to my Boardwalk. Now I am inspired!
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Old 06-13-17, 08:30 PM   #18
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Quote:
Originally Posted by HighValleyRanch View Post
I just got my first folding bike, a cheap Allen Sports "Downtown".
Great price at 110.00 shipped for an aluminum frame.

The main problem is that it is a one piece stem, that is 14 inches tall! from the head tube to center of bar. Great it you are 6 feet tall, or want to sit in a totally upright position, but being only 5'7", and riding usually 50 cm road bikes, I want a shorter stem. Either an adjustable length stem or one that is about 4 inches shorter.
Welcome to the fold!

That is nice looking bike! What a great price. I had a Norco Fiori 8 folding bike, and the handlebars were just too high. I'm 5'7" as well. After getting a Dahon Curve that could fold small, I decided to make the Norco less foldy so that it could have lower bars.

I ended up getting a Delta Stem Raiser and a standard stem and some new handlebars.
https://www.mec.ca/en/product/5042-6...oy-Stem-Raiser

The bike still folded small enough to throw in the hatchback of the car, and I could twist the handlebars sideways by loosing to the two hex nuts on the stem. I rarely had to do this.
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Old 06-13-17, 08:39 PM   #19
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Edelay,
So that stem riser clamps onto the steering tube and then what size (diameter) quill stem do you insert into that?
Also does the riser have the bolt that goes down into the star nut to secure it to the steering tube? I would not want to rely on just clamp to hold it on.
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Old 06-14-17, 07:58 AM   #20
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Quote:
Originally Posted by HighValleyRanch View Post
Edelay,
So that stem riser clamps onto the steering tube and then what size (diameter) quill stem do you insert into that?
Also does the riser have the bolt that goes down into the star nut to secure it to the steering tube? I would not want to rely on just clamp to hold it on.
Your bike is a threadless stem and so is the riser. No quill.

The stem riser has a long hex/allen key bolt that goes down into the star nut. You would use that bolt instead of the bolt from your bike. You'll likely need a few spacers.

You'll definitely need to do some measurements to see if with this stem riser, if the handlebars are too low. There is also a pro version of this same riser which is a bit taller. I was able to find that brand of riser at a number of place along with no name versions on ebay and alixexpress. I bought mine from a local store so I could return it just in case the hex bolt threads were different or there were other issues connecting it.
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Old 06-15-17, 03:44 PM   #21
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Went for a 1/2 hour ride on the bike this morning on a coastal bike trail that winds from Half Moon Bay (CA) north. BEAUTIFUL! Early enough so there were too many people out, and the bike handled perfectly.
Very smooth, and extremely quiet. Out into a headwind, but coming back with a tail wind, and all you could hear was the tires rolling on the pavement. Love that quiet.

The gearing is around mid fifties inches, so on the flats I was spinning as fast as was comfortable, but not traveling as fast as the roadies who past me. But I was happy to go along at a good clip, and enjoy the scenery and quiet. I'm hooked on folding bikes now! Saw a couple of other riders on their folding bikes as well.

Is there a site, or chart or calculation that helps to figure the mph for a given gear inch to wheel size?

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Old 06-16-17, 06:18 AM   #22
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Quote:
Originally Posted by HighValleyRanch View Post

Is there a site, or chart or calculation that helps to figure the mph for a given gear inch to wheel size?
Try Sheldon's calculator here: sheldonbrown.com/gear-calc.html
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Old 06-16-17, 02:48 PM   #23
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Thanks for the link.
I found that on this Allen Sport Downtown single speed, it has a 48 stock front crank with a 16 tooth rear cog freewheel. That gives me a 60" gear, and so at 90 rpm on the flats I can go 16 mph. Crank it all the way up to 110 and I would be able to get 19.5 mph.
Plenty fast for a single speed with little tires.
But last night I changed the crank out to a Gipiemme single chainring crank with 46 tooth, so I have a little lower gear for the hills around my house.
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Old 06-26-17, 10:33 AM   #24
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Got one to work!

A BIG THANKS TO PINIGIS in getting me a shorter adjustable stem to work with my Allen Sports Downtown.
Now the height matches my Mini Velo.
With help like that, I would not hesitate to purchase one of his bikes!

I had to cut about three inches off the sliding stem, but easy mod and now it is the perfect height and can be adjusted higher back to the original if desired. Fit was perfect match and it still folds to the outside as before.
Now I'll have to find a black seat post to match however!

Here is the bike with the shorter stem.
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Old 06-26-17, 10:50 AM   #25
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Quote:
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A BIG THANKS TO PINIGIS in getting me a shorter adjustable stem to work with my Allen Sports Downtown.
Now the height matches my Mini Velo.
With help like that, I would not hesitate to purchase one of his bikes!

I had to cut about three inches off the sliding stem, but easy mod and now it is the perfect height and can be adjusted higher back to the original if desired. Fit was perfect match and it still folds to the outside as before.
Now I'll have to find a black seat post to match however!

Here is the bike with the shorter stem.
The bike looks great! Glad I could help.
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