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  1. #1
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    KENT Magnesium Folder - a real folding bike

    Hi everyone
    I thought I would restart this thread - as the one I started before disappeared. Shame, because there were good discussions about Magnesium as a material, postings of a different bike with the same frame, as well as a video of how it folds. I also wanted to have the thread have a proper starting title, hence my rational of starting it fresh instead of continuing the where did the Kent bike thread go - thread.

    Anyway, I finally got my Kent bike today from Amazon (who are now sold out for the time being by the way - maybe due to this forum? It more or less met my expectations. The frame is great, really stiff, seems really strong, and is ultralite. The casting is quite amazing actually. I really like the way the bike looks. The bike came assembled - but will need plenty of adjustments. The wheels are pretty true. The brakes will just need a little adjustment, and are pretty decent. The rear derailleur seems really poor - and will need adjustment to shift the full range (if it ever will). The fork stem is over tightened and will need adjustment. Regardless, I was able to just pump up the tires, and try out the bike tonight. So here's the good, the bad, and the ugly:
    Good:
    - Handlebar, handlebar stem, seat post, rims, quick locks, brakes, baggage rack, and crank arms are all aluminium alloy and look to be pretty good quality - better than expected.
    - The bike is full sized - meaning it's meant for adults
    - The bike is light as advertised
    - Shows well
    Bad:
    - Crank length: 155mm - too short. The bottom bracket is pretty low - so putting on longer cranks may be an issue. I'll do it anyway.
    - Drive train really rough - haven't figured out which part yet, but either the bottom bracket, the freewheel, and or the derailleur run rough and sticky. I'll need to take the BB and the frewheel apart probably and adjust.
    - Handlebar - it's got a great handlebar that's welded together with the stem (which fits in and adjusts in the fold up aluminum tube). It's light, but it's really high, and too close to the rider. I'm 5'10" and the handlebar, at its lowest setting, feels too high for me. So I'll have to get a new stem and handlebar.
    - Saddle - I hate seats with springs - will need to put on another one

    The ugly:
    - Tires - they look like molded plastic tires - hold on - they are molded plastic tires!
    - Derailleur - need a new one, the grip shift looks decent enough though
    - Pedals - the folding pedals are really poor quality, hardly spin, and are annoying, since you can only use 1 side.

    Overall, I'm pretty pleased with the bike. Keep in mind the price. I'll swap some components and it should come in even lighter. One thing I'm thinking of is swapping the 16" wheels out - the back will take a 20" wheel, and if I swap the fork out, I'll be able to upgrade it to a 20" folder. The only reason I'm thinking about this is to raise the bike overall, in order to fit a 175 crank comfortably. Thoughts on this?

  2. #2
    jur
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    Could you please measure the horizontal distance between seatpost and handlepost (centre distance)? This will tell me finally what "size" the bike is - I expect to have to put on a threadless stem and bars to move the handlebars forward, but if too close, then not.

    It is very important to measure this dimension with the bike on a level surface with the measuring tape held level as well - a small error produces quite a large result error.

    Why shouldn't you use 170mm cranks? Even 165mm? My MTB has 175mm, my Raleigh 20 has 165mm, and my roadie 170mm, and I can not really detect any difference, except that with the MTB my thighs come closer to my body. Pedalling effort etc seems just same.

    Could you post a pic of how the BB shell is attached?
    My folding bike photo essays www.dekter.net/

  3. #3
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    Will do, but probably won't get a chance till tomorrow. In the meantime, some additional notes:
    - The crank arm is actually 152 mm. It definitely doesn't feel efficient. Jur - as you suggested, I'm considering putting 165 mm cranks on it. Those should clear the ground easily. I've given up the thought of switching to 20" wheels, the bike looks cool with the small wheels.
    - The bottom bracket is cast with the frame - it is not attached separately. It looks very strong - as well as the whole frame. As I wrote, the casting is quite sophisticated - within the main dowtube, it is honeycombed on the inside, and it has well placed strenghteing ribs elsewhere (including at the bottom bracket). Although it looks like it might be a problem in the photos, there is no way it or the rear wheel attachement points could bend due to pedaling force. I'll post pictures.
    - I just needed to loosen the crank a bit, and the bottom bracket spins freely.
    - After removing the derailleur protector - the derailleur shifts freely. Pretty dumb - the protectors didn't allow it to shift all the way down. It actually works well now, and hence I could avoid the need to put a better one on (for now anyway).

  4. #4
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    Link to the bike with picture of BB: http://www.amazon.com/Kent-Ultra-Mag...sporting-goods

    The issue with the BB is not the rear wheel. The connection between the BB and the frame will get a large bending stress. The stress will also be cyclical as the cranks spin, which makes it worse.

    My guess is that even if this is a bad design you would really have to use it a lot for it to become apparent. For example the 'mast' steering tube on the Birdy and Dahon seem to have failed on a few bikes. Even if the BB fails it is not a safety issue, like a steering tube (ouch).

    Note in addition to the magnesium frame, the BB is the other radical design approach on the bike. That's why it is getting attention.

    For $150, you have a lot of room to upgrade. This could really be competition for presto light, downtube and dare I say Brompton.

    The cast frame is a real cost saver. The Brompton people put a lot of effort into welding/brazing.

    I bet if you really threw money at it you could take another lb or 2 off the weight.

    Or you could forget about weight and get suspension hubs http://www.pantourhub.com/ and a thud buster. That's one way to get that $150 to a more respectable number.
    Last edited by geo8rge; 11-30-06 at 07:45 PM.
    2000 Montague CX, I do not recommend it, but still ride it.
    Strida 3, I recommend it for rides < 10mi wo steep hills.
    2006 Rowbike 720 Sport, I recommend it as an exercise bike.
    1996 Birdy, Recommend.
    Wieleder CARiBIKE (folding), decent frame.

  5. #5
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    Attached are pictures I took of the bottom bracket, rear frame design, and measurements of the distance between seat post and stem.
    http://www.kolega.com/kent.htm

    Hope this helps. For the stem, I'm thinking of finding a road bike aluminium stem + a straight, or bullhorn handlebar.

  6. #6
    rhm
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    Yo, thanks for all the info, it is very helpful. Yesterday I test rode a Swift, and liked it, but was not optimistic about possible customizations. Fenders are a must for anyone who commutes regularly, and I couldn't see how good fenders would fit the Swift. I would like to put a generator hub in the front wheel, which means pulling the wheel off is a pain, and to make the Swift small you really have to do that... and I don't like the kind of rack the Swift accepts. Too bad; I thought the Swift would be perfect for me. So then I was seriously looking at a Brompton, but just couldn't face the price tag, which was somewhere around $1150. Maybe it's worth it; but that's almost four times what I paid for my Strida! Now, on your recommendation I have ordered the Kent, at over $1000 less. Amazon has them in stock, by the way.
    It will feel strange to spend $300 on a new front wheel for such a cheap bike, but I can do a lot of customization before the price approaches that of the Brompton... or even the Swift!
    I will keep y'all posted.
    Cheers!
    Rudi

  7. #7
    Part-time epistemologist invisiblehand's Avatar
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    Quote Originally Posted by rhm
    Yo, thanks for all the info, it is very helpful. Yesterday I test rode a Swift, and liked it, but was not optimistic about possible customizations. Fenders are a must for anyone who commutes regularly, and I couldn't see how good fenders would fit the Swift. I would like to put a generator hub in the front wheel, which means pulling the wheel off is a pain, and to make the Swift small you really have to do that... and I don't like the kind of rack the Swift accepts. Too bad; I thought the Swift would be perfect for me. So then I was seriously looking at a Brompton, but just couldn't face the price tag, which was somewhere around $1150. Maybe it's worth it; but that's almost four times what I paid for my Strida! Now, on your recommendation I have ordered the Kent, at over $1000 less. Amazon has them in stock, by the way.
    It will feel strange to spend $300 on a new front wheel for such a cheap bike, but I can do a lot of customization before the price approaches that of the Brompton... or even the Swift!
    I will keep y'all posted.
    Cheers!
    Rudi
    If you really like the Brompton but want something less expensive, you might want to consider the Merc.

  8. #8
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    Kent Folder is available for $117.99 after coupons at Amazon

    I'd been sitting on the fence, but at this price :-)

    Amazon's taking $10 off, plus you can use coupon code AMZNSGO6 to get $20 off. My order confirm looked like this:

    Subtotal of Items: $147.99
    Shipping & Handling: $20.96
    Super Saver Discount: -$20.96
    Promotion Applied: -$20.00
    Promotion Applied: -$10.00
    ---------
    Total for this Order: $117.99

    Make sure you pick free shipping.

    Cheers, Sy.

  9. #9
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    Damn it! I know I should have waited a bit - by the way how did you get the coupon code?

  10. #10
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    The 'fin' on top of the BB indicates someone was worried about the BB being properly supported.

    The lug with the screw hole extending behind the BB is curious. I wonder what that was for? Perhaps at some point there was going to be a support from the BB to the rear axil?

    It looks like the front and back are each a one piece casting. They did not do a left and right and weld them together.

    As far as spending money on a wheel, one reason Bromptons cost is that they have an SRAM dual drive rear hub and other expensive parts.
    Last edited by geo8rge; 12-01-06 at 02:31 PM.
    2000 Montague CX, I do not recommend it, but still ride it.
    Strida 3, I recommend it for rides < 10mi wo steep hills.
    2006 Rowbike 720 Sport, I recommend it as an exercise bike.
    1996 Birdy, Recommend.
    Wieleder CARiBIKE (folding), decent frame.

  11. #11
    jur
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    What is the distance from BB axle to floor?
    My folding bike photo essays www.dekter.net/

  12. #12
    Senior Member randya's Avatar
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    Quote Originally Posted by syali
    I'd been sitting on the fence, but at this price :-)

    Amazon's taking $10 off, plus you can use coupon code AMZNSGO6 to get $20 off. My order confirm looked like this:

    Subtotal of Items: $147.99
    Shipping & Handling: $20.96
    Super Saver Discount: -$20.96
    Promotion Applied: -$20.00
    Promotion Applied: -$10.00
    ---------
    Total for this Order: $117.99

    Make sure you pick free shipping.

    Cheers, Sy.
    I couldn't resist. This worked for me, I got the $117.99 deal!

    When I placed the order, I got a page of promos for three other folding bikes Amazon sells, 2006 Dahon Speed D7, $320; Chrysler one-speed PT Cruiser 16", $230; and Schwinn Run-About 7-speed (?) 20", $200. I would assume some of the same discounts (free shipping + promo discounts) would apply to these other bikes. This is the URL I got for the other bikes: http://www.amazon.com/gp/product/han...872575-2606860

    I could have gotten an additional $30 discount if I had signed up for an Amazon.com credit card, bringing the total down to $87.99.
    Last edited by randya; 12-01-06 at 11:49 PM.

  13. #13
    Senior Member randya's Avatar
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    Here's some specifications from http://www.bikemania.biz/Kent_Ultral...kent_61688.htm

    Specs:
    Frame 16” Magnesium Folding Frame; Die Cast
    Fork 16” Alloy; Unicrown
    Chain KMC Z 30
    Crankset Alloy 3Pcs L=145mm; 46T
    BB FP-B602 5 pcs
    Rear Derailleur Falcon RD-22 6SPD
    Shifters Falcon Grip Shifters
    Brake levers Artek Alloy /Resin
    Brakes Alloy Linear Pull V-Brakes
    Rims Alloy 16”X1.5”X20H
    Tires 16”X1.75 All Terrain Black
    Stem Aluminum 22.2 Folding
    Handlebar Alloy Singlebar Upbend
    Saddle Cionlli Comfort Seat with Steel Springs
    Seat post Alloy 29.2 X 500mm with Quickrelease
    Pedals Foldable; Resin
    Carrier Alloy
    Weight 23.0 lbs
    Max. Rider weight 200.0 lbs
    Dimensions folded 27”X24”X15”

    Some other interesting folders at bikemania.biz as well: http://www.bikemania.biz/Folding_Bicycles_s/17.htm

  14. #14
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    More important question: what is the distance from center of BB to top of seat at max seat extension (following seat tube)?

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    Any info on gear range (in gear-in)?

    Do rims take 305 tires?

    Anything else look like it can't be taken apart?

  16. #16
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    Some more info: center of BB to floor is about 9.5", center of BB to top of seat - at full extentision, is about 26" - but I have it extended an extra 2" past the safety line without any problems. One thing I did realize though, is that the seat tube is in front of the BB, not on its centerline. The bike felt a bit strange to ride, until I moved the seat aft as far as possible. It's now better, but, the range isn't that great, so I'll keep an eye for a replacement saddle that can be adjusted further back. The good news with this is, that this increases the length to the stem - in fact, I don't feel I need to displace the handlebar forward anymore. Another simple modification - as lot of reviewers on Amazon complained about the handlebar sticking out when folded - is to rotate the folding stem so that the handlebar folds on the other side of the frame. The folded width is about the same, but the handlebar doesn't dangle out, and the brake levers are better protected. See attachement. Also note, now that I actually weighed the bike, it weighs 25 or 25.5 pounds, I assume the 23 pounds specification is without the luggage rack and kickstand. I believe the lug and hole behind the BB is for a more traditional type of kickstand. Not sure what 305 tires are, and I haven't had a chance to count the speeds yet - the range is pretty wide.
    Attached Images Attached Images

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    Thanks for the specs on seat post length. Sounds like 710mm is all you can expect even with cheating.

    305 is an ISO tire size; checking to make sure it's not a weird size for which replacement tires wouldn't be possible. Can you check and see if iso305 is stamped on the sidewall of the tire?

    http://www.sheldonbrown.com/tire_sizing.html

    Appreciated your quick response!

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    I'm curious too: does it look like the BB spindle is a square taper? Or that the cranks could be replaced if desired? That's suspicious if the BB is integrated somehow; because that may make it impossible to replace the cranks.

    Problem with many of these neat little folders are strange replacement parts.

  19. #19
    jur
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    Quote Originally Posted by jasong
    I'm curious too: does it look like the BB spindle is a square taper? Or that the cranks could be replaced if desired? That's suspicious if the BB is integrated somehow; because that may make it impossible to replace the cranks.

    Problem with many of these neat little folders are strange replacement parts.
    Strange parts is usually the domain of expensive folders. The cheapies use mass-produced off-the-shelf bits as far as they can. I would bet money on it it is a square taper with standard thread.

    The short cranks is interesting. That length is for kids. Probably more as cheap as possible parts. I have seen folders in a department store in Taipei; the general quality was so poor I lost interest. That's not to say the Kent is no good. The frame is really interesting. The 9.5" BB height is workable. I just checked all my bikes and the MTB is highest at 11", the rest is around 10".

    The seat tube to steerer post is on the short side, but may be workable.
    My folding bike photo essays www.dekter.net/

  20. #20
    Seņor Mambo
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    I'm sure the shorter cranks are meant to encourage spinning rather than mashing in addition to saving weight and not striking the ground.

    On another note, in the scooter world (Xootr specifically), decks made from Mg tend(ed) not to be as durable as the decks made from Al or wood. Don't know if this relevantly translates to bikes though.

  21. #21
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    The only thing unique on the bike is the handlebar stem, which I've photographed before. That is the stem and the handlebar being welded together. You could easily replace the whole thing. Everything else is standard, including the crank - which is square taper. The BB is standard non-sealed type - it's only the BB housing that is cast together with the frame. And yes the tires are 305. The manufacturer is Wanda - has anyone heard of it? The crank is shorter due to the lower BB position - but should still accomodate a full size crank actually. I really don't know why they put something so short on it - nothing else is kid sized on the bike. Actually, my kids had real difficulty riding it, due to the handlebar being too far and too high. I think one good upgrade would be to put the slighlty larger Brompton type wheels on the bike, and at the same time switch to a cassette hub. You guys aren't going to be overly impressed with the wheels on this thing.

  22. #22
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    Reducing folding width

    Is there a way to reduce the folded width of the Kent to 13.5"? Adjusting and folding the steering as mentioned and/or removing the outboard pedal? I am limited to this size opening to store on a boat. Thanks in advance. Mike

  23. #23
    Senior Member randya's Avatar
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    305 is a common tire size, many options are available for upgrading the tires.

  24. #24
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    The only way to get it to 13.5" is to slide out the handlebar. This would leave it dangling, but than you can fit it better next to the bike, so that it doesn't stick out. That should work since the main handlebar stem folds flush against the body, and the two halves of the frame also fold flush against each other. (It doesn't look like it in my picture, because the handlebar is in the way, but without it, they do.) It already has folding pedals, although they don't save as much as a removable pedal. So if you replace the right pedal with a removable one, it will fold even flatter.

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    I had posted in that first thread, very early in its run, to the effect that I did not see how a bike could be built out of an exotic frame material at the $100.00 price point. I didn't know then some things that came to 'light' later after the thread developed. Nothing I have read since changes my opinion: "if it sounds too good to be true, it likely is". First, Magnesium is actually not that exotic when you think about it. Tons of things like cases for electronic equipment and of course those ubiquitous Maglite flashlingts have been made out of cast magnesium for decades. The amounts used in those applications don't come close to what a bike frame, even a small one requires and this is what threw me initially. Secondly, the frame is die cast. Likely it is a magnesium alloy and not pure magnesium and after casting, very, very different in yield strengths and tensile characteristics from the steel, aluminum, titanium or graphite fiber tubings intended for quality bike frames. I'm just nitpicking to make a point, for it's intended purpose that frame is probably just fine but lets not kid ourselves (which is what some of us are doing) it is probably as dead as a doorknob as far as ride quality is concerned. And, as I said before, at 23lbs it is hardly light for a 16" bike. I am fairly certain the intended market for that machine is a youth niche and an adult expecting to get much utility from it will be frustrated/disappointed. When I buy a bike, at any price level, I expect to do minimal 'upgrading'. I should be able to enjoy it out of the box whatever it costs and it can be done if the buying is done carefully. Putting on 20" wheels, changing componentry is IMO buying two bikes to make one. For me upgrading means adding bottle mounts or blinkies or pumps, racks, etc. to make the bike easier to live with. I should be able to at least live with the components the bike comes with till they wear out, or in the event that I really have some kind of project in mind (like substituting a dual drive rear hub) the OEM components should not be so horrible that they have no intrinsic value of their own to aid in the swap). Just my opinion.

    H

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