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  1. #1
    Wheelsuck Fat Boy's Avatar
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    Downtube FS IX review (long)

    OK, Hereís my Downtube FS IX review. I got it a couple weeks ago. I have a reasonable amount of bike experience, but Iím not a complete bicycle maniac. The reason I wanted a folder is because I work on racecars which means I travel all the time. When on the road I end up stranded in a hotel a lot. Having a bike that I can take with me gives me access to transportation, gets me some exercise, and keeps me out of the bars!

    From the time I opened the box to actually riding the bike was probably less than 15 minutes, and I even read some of the directions! I think the bike looks pretty cool and I was happy with the initial overall looks and finish. The riding position is much better that I expected it to be. The bike is well balanced and handles nicely. The 20Ē wheels are plenty big enough to be stable. Maybe I could have gotten away with the 16Ē bike, I donít know. I did travel on United with the bike in my new Samsonite FíLite 31 case. I checked it at the curb in Los Angeles. It cost $2 per bag for curb service. I gave the guy a 20, checked my 2 bags (the FíLite was 48 pounds and the other was 40), and asked the guy not to bother putting the bags on the scale.

    I never leave a bike stock. Itís just in my blood. Iím a mechanical engineer and my job is working primarily on car suspensions. Iím a confessed and unapologetic tinkerer.

    My first bit of tinkering happened very early. Right away, I started to try and figure out how to get the bike into the Samsonite case. Itís a little bit of a trick. To get the fork to Ďnestí in the rear stays, you have to disconnect the shock and rotate the swingarm out of the way. When I did, I couldnít believe how much force it took to move the swingarm. With no shock, it should freely swing. Well, it doesnít. So that was the first thing that I started playing with. I pulled the pivot apart and measured it all up. The plastic (nylon?) bush has a little over 1mm of crush on it as delivered. This means there is so much friction, that the spring/shock really never get a chance to operate. No wonder some of the reviews I read stated that the 850# spring seemed too stiff!

    Well, I made a spacer to put in the middle of the swing-arm axle. Originally, I took all of the crush off the bushing. That caused some frame stiffness issues (Iíll get into later), so I put some of the crush back in. Iím at about 0.4 mm right now, and itís a good compromise. The suspension doesnít feel too stiff at all, and think it could probably use a little more damping.

    My first feeling while riding was that the gearing was a little low for me. Sure, if I were actually using this as a mountain bike, then Iíd probably need some real spinning gears. That isnít what I have this bike for, and I really donít think itís what anyone has this bike for. So I decided to step up from the stock 46 tooth to a 53t chainring. I like the 53. Another reviewer said that it was a little tall, and heís probably right. On the open road itís nice, but to go up a steep hill, you better be prepared to get a little down and dirty. My travels have taken me to Mont Tremblant in Quebec, Canada. Itís a ski village and has some real mountains. My hotel is Ĺ way up one and getting up that hill is a *****. I doubt if I see any bigger this year. Anyway, Iím using it as a catalyst to get in better shape. If I ride it enough, it wonít feel tall. Pedaling around town, I use 5-6-7th gear, which is right in the middle of the range and it feels nice. Also, be sure to set your derailleur tension and limiters, they come backed out all the way.

    The first chainring I bought was for the stock crankset. In higher gears, all I had to do was put 10% of pressure on the pedal, and it would throw the chain off the pedal side of the chainring. I noticed the chain was actually a 7/8 speed chain, so I changed to a 9 speed chain and made it extra long to account for the added teeth on the chainring. That didnít really help. After looking closer I then noticed some pretty major deflections out of the stock crankset. Letís be honest, the stock crankset is crap. Aluminum arms and a stamped steel spider pressed on it not a good way to go. I replaced that with a modest FMF BMX crankset, which took another chainring bolt spacing. No big deal, but it sucked to have to buy the same part twice. While replacing the cranks, I noticed the bottom bracket bearing was way, way too stiff. Someone had that bearing preloaded to beat hell. So I set that up properly. That seems to be a common deal. These bikes are built quickly by people who either donít really know the right way to do it, are instructed to do it in an improper manner, or just donít care. The change in crankset made a big difference on throwing the chain. Now I had to be pedaling pretty hard to get it to come off. The deflection of the swingarm pivot was starting to be an issue now, so I stuck some of the preload back in it, and that has (almost) fixed the problem entirely. Now on a Ĺ hour ride, being very conscious to shift slowly and not do anything to confuse the matter, it will probably throw the chain once. This is more than I like, but I can live with it. I will probably get some sort of chain guide soon.

    Observations:
    1. The fasteners used on this bike are crap. The headset allen that needs to come out to get the bike in suitcase was stripped when I got it. I donít know how Iíll get it out. I came up with another way to get it in the case, but coming from the factory that way sucks. Also, the shock mounting bolt stripped on me the second time I was installing it. Keep in mind that I do a fair bit of mechanical work in my professional life. Iím not a rock-ape with a crescent wrench. The fasteners are junk and need to be replaced.

    2. If you are asking the plastic bushing in the swingarm to not only control rotational motion, but be a big player in the torsional stiffness of the bike, then it needs to be much bigger in diameter. I have an old Schwinn mountain bike (1998 model) that used something similar. It did to with a large diameter tube and a well supported positioning of the bushing. Ultimately, I believe this should be 2 sealed ball bearings with a crush sleeve between them. The loads that youíre putting into this thing just canít be efficiently controlled by the present arrangement. At some point I think Iím going to do a redesign.

    3. Now that Iíve set up the suspension to actually move, it has the tendency to shift gears due to rear swingarm movement. If you hit a big bump, youíll likely shift into the next gear. I might be able to play with chain length to get rid of this, but I think itís the nature of the beast.

    4. If you stay in the saddle on level ground, the bike feels pretty good. If you try to stand up and sprint or climb a steep hill, the bike really moves around underneath you. This has to be just a part of being a folding bike, but itís something that needs to be acknowledged. Iím not very sensitive to this. Iíve never noticed it on any other bike, so it must be pretty pronounced.

    5. This bike really shouldnít really be used off road. The tires are road tires and narrow. This bike is represented as having off-road capabilities, but in reality, stay on tarmac. At one point I road on the shoulder of a road and it was pretty dicey. A proper mountain bike wouldnít even have cared, but I was actually having to do a little work to keep upright. Off-road isnít new to me. I live in Southern California which has really great mountain biking and plenty of loose dirt/sand to ride in.

    6. The brake and derailleur lines should probably be replaced. Theyíre not the greatest quality. The housings have a lot of flex.

    7. If I would have had a couple of these to ride before ordering them off the web, I think I may very well have ended up with a hardtail frame and an internally geared hub. Maybe my gear spread wouldnít have been quite as big and my ride would have been a little rougher, but Iíd be chasing the shifting around a lot less. That alone would be a big gain. I donít know what derailleur would be an easy swap as a replacement for what Iíve got, but Iím probably going to buy one. Iím not overly impressed with the JuJu.

    8. I paid $309 for my bike. For that kind of money, I think the bike is a good buy. Itís doing everything I ask from it and Iím glad I bought it. Having said that, Iíve also put about $100 into getting it more set up to my liking and I'll be spending more in the future. If I would have bought a $500 bike, Iíd expect it to have significantly better components. Iím a little surprised that the new Downtubes are so much more expensive. The only difference I can see in them is the new fork. I think they need to be very careful with the pricing. I can see offering a higher end version with better components throughout, but I think theyíre advantage in the market right now is in the Ďbang for the buckí game. They need to not lose sight of that.

    Summary:
    In short, Iím happy I bought the bike. It gets me out and riding in places that I just couldnít have before. The bike has some cheesy components, but they can all be changed. Iíd like to see better build quality and quality control in the hardware of the bike. I also think that the rear suspension / swing-arm could use a significant re-design. The full-suspension is an interesting choice to have, but, ultimately, I think getting a hardtail is probably a better choice for most users. Looking at the bike as a whole, I think Iíll give it a 8/10 rating. Itís a good choice, but not an absolute slam-dunk. If you ride it very much at all, youíll probably be doing a number of upgrades.

  2. #2
    Eschew Obfuscation SesameCrunch's Avatar
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    Thanks for the detailed review! It'll help a lot of folks out in the future. It's going to be great having you on these forums. Your attention to detail and your mechanical background will make you a great asset here!

    I had to chuckle at your BB experience. I just automatically loosen and grease the BB's whenever I get a DT (have had 6 now). I don't know what the process is at the factory, but I have this visual image of a Yao Ming sized guy with big forearms torquing them down

    I also agree with you on not needing the rear suspension. My first DT was a full suspension also because I was unsure of the comfort of small wheels, but now I find the ride is just fine at reasonable psi's. The rear suspension just gets in the way of pedaling efficiency.

    Congrats on your new bike. Hope you have lots of fun as I do with mine.

    PS: The reason the 2008s are so much more expensive is because Yan is trying to move out his older stock as fast as possible. The 2008 prices are likely to come down later.

    PPSS: Heck of a deal on the bike @ $309!!!

  3. #3
    jur
    jur is offline
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    I give this review 10/10.
    My folding bike photo essays www.dekter.net/

  4. #4
    SeŮor Mambo
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    Your review is very informative, but your summary is a bit confusing. Given what you've written, if I knew I'd have to spend $100 - $200+ in addition to what I've already spent because of a bike that needed "better build quality and quality control in the hardware of the bike" if not an outright "redesign" of the swing arm, I don't know if my rating would be as generous (though I realize ratings are subjective). Maybe you need a rating break down like Consumer Reports.

    By the way, was there a reason why you didn't take advantage of DT's return policy?

  5. #5
    too many bikes
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    Fat Boy, nice to read an ME's review of the DT FS. I hope you stick around the Folding forum.

    You opened Pandora's Box when your modsmanship took you into the swingarm bushing. The first time I rotated the swingarm down for packing, I, too, was very tempted to "improve" the swingarm mechanics, but I demurred, since the rear sus did work well with almost no preload on the coil spring (I'm 200 lb.). It was the front sus that I couldn't tolerate. As a result...
    The Mauna Kea bike

    I'm sure Yan would welcome an ME's suggestions about a reengineered swingarm pivot, especially a design that could be implemented in technologies and by assemblers available in China.

    Oh yes.... the crankset spider has been known to taco, so if you like standing on the pedals, it's just as well that you replaced it.

    As for the final score, for the money, I give the DT FS 10/10. To improve on what you got for $309 in another product line, you're lookin' at 2x or 3x the DT FS price.

  6. #6
    Bromptonaut 14R's Avatar
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    If I own a bike business I would give you bikes just to get that kind of quality, unbiased review! 10/10.
    Thank you for the time to write it down.

  7. #7
    Part-time epistemologist invisiblehand's Avatar
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    Quote Originally Posted by SesameCrunch
    I had to chuckle at your BB experience. I just automatically loosen and grease the BB's whenever I get a DT (have had 6 now). I don't know what the process is at the factory, but I have this visual image of a Yao Ming sized guy with big forearms torquing them down
    Make that some guy with Popeye forearms torquing down the cups without any grease or anti-seize lube. Mine was as dry as a desert.

  8. #8
    Eschew Obfuscation SesameCrunch's Avatar
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    Quote Originally Posted by invisiblehand
    Make that some guy with Popeye forearms torquing down the cups without any grease or anti-seize lube. Mine was as dry as a desert.
    +1. All of mine were dry too.

  9. #9
    Senior Member downtube's Avatar
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    Quote Originally Posted by Fat Boy
    OK, Hereís my Downtube FS IX review. I got it a couple weeks ago. I have a reasonable amount of bike experience, but Iím not a complete bicycle maniac. The reason I wanted a folder is because I work on racecars which means I travel all the time. When on the road I end up stranded in a hotel a lot. Having a bike that I can take with me gives me access to transportation, gets me some exercise, and keeps me out of the bars!
    Thanks for the objective review. I'm glad you liked the bike, and I thank you for your critique as well. We are striving to make our bikes the best we can. We really need input from you and other customers.

    FYI I have taken this bike off-road many times, I think it does very well in light to moderate trails. Additionally we have about 550 2007 IXFS remaining. They would loose value if we introduced new bikes at the same price. That is not an option since we already wholesale our bikes to the public.

    Thanks,
    Yan

  10. #10
    Wheelsuck Fat Boy's Avatar
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    Well, I guess I came up with an 8/10 trying to put it all into perspective. One of the things that has to be acknowledged is that over the last week I spent about 4 1/2 hours on a bike. That wouldn't have happened without a folder. Even spending the extra money, my Downtube was less expensive that any other option.

    Had I not changed the chainring and swingarm spacing, I probably wouldn't have had the problem throwing the chain (although I would then be complaining about the gearing and ride). It's hard to fault the bike for something that I did, ya know?

    I believe the build procedures (no lube and stripped bolts) are legitimate gripes. I also think the low overall fastener quality is a legitimate gripe. Beyond that, the actual construction of the bike frame is pretty nice.

    I don't see a swingarm redesign is that big of a deal. It's perspective, I guess, but going from a nylon bushing to a ball bearing could be accomplished with a few different parts and a couple different machining processes. All in all, it wouldn't affect the overall price of the bike significantly.

    So my 8/10 is because I'm pretty happy with the bike as an overall piece of kit. The ergonomics of the bike are surprisingly comfortable (I'm 5'9" / 155#). I haven't ran into anything that would leave me stranded. Do I think it's perfect, no. I rarely think anything mechanical is perfect. Do I think it will probably serve a lot of people's needs and do so for 1/2 the money of the competition, yes.

    So I've now left Mont Tremblant, a ski village with bike trails through the woods. This week, I'm going to be riding through the streets of Toronto. Let's see how it acts in a completely different environment.

  11. #11
    Wheelsuck Fat Boy's Avatar
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    So about a week ago I had my 5 days in Toronto, and I take off for Edmonton on Wednesday. Another 5 day deal.

    My DT is treating me pretty good. The route that I had in Toronto was from Yonge street and Dunhill(?) to Exhibition Place. It's about a 15-20 minute trip. 1/2 of it is on the streets and 1/2 is on a bike path by the water. No biggie really. The Toronto traffic is used to having bikers around pretty much everywhere, but they sure don't cut you any slack.

    The chain throwing thing on my bike is really starting to get old. The derailleur gets hung up very easily and it somehow gets pulled way too far forward and then sticks there. This takes all the tension off the chain. Any attempt at shifting once this has happened is pretty much a sure thrown chain. I've tried to keep everything as clean as possible and used plenty of Tri-flow. It's still a pain. I think the stock 'bash guard' is really more of a chain guide. I've bought some Lexan at Home Depot and I'm going to make a custom one if I get the time.

    I also bought a SRAM X.9 derailleur to put in place of the JUJU. I'm not sure if I can used the stock shifter, so I picked up a SRAM grip shifter, too. I'm away from my bike right now. The work will happen on Thursday. Hopefully this will address the issues that I'm having right now and make for a happier ride (and rider).

    Oh ya, if you're in Toronto and jonesin' for some cheap Mexican food, try Burrito Boyz. Weird name, I know. It's just a hole in the wall on Peter street. I was highly skeptical, especially since there wasn't a Mexican guy or gal actually on the stove, but they put together a good Halibut Burrito with Guacamole and a hot salsa.

  12. #12
    Senior Member JeremyZ's Avatar
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    Quote Originally Posted by invisiblehand
    Make that some guy with Popeye forearms torquing down the cups without any grease or anti-seize lube. Mine was as dry as a desert.
    I bet it is some skinny Chinese guy with a pneumatic ratchet.

    Yes, excellent review.

    Hey, to solve the chain-throwing problem, have you considered going back to the stock setup? We'd like to hear how reliable that is.

    After reading this review, I'm glad I followed my instinct and stuck with the hub gear on my folder.

    Why don't more of the folders use hub gears? Is there some disadvantage I don't know about?

  13. #13
    Senior Member JeremyZ's Avatar
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    Oh, one other thing. 5'9" and 155? Fat Boy? Very funny. I'm 5'8" and 173 and don't consider myself fat. I could probably afford to lose 10 lbs worth of beer belly, but no more than that.

  14. #14
    Wheelsuck Fat Boy's Avatar
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    It's kind of a left over name. I just stick with it.

  15. #15
    Wheelsuck Fat Boy's Avatar
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    I just made an upgrade. I stuck an SRAM X.9 rear derailluer and a X.0 shifter. The problem I've been having with the chain being thrown just went away. I'm convinced the stock JUJU derailluer is pretty much a P.O.S. I stuck the new derailluer on and, just so you know, the stock shifter doesn't use the SRAM 1:1 ratio, so I had to get a new shifter. I got last year's X.9 and X.0 pieces pretty cheap.

    The difference in the bike is _huge_. It reminds me of when I went from an STX setup to an XT setup many moons ago. There's no more chain throwing or false shifting. It's not a cheap upgrade, but it's definitely worthwhile.

  16. #16
    jur
    jur is offline
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    It would be interesting to compare derailer spring tensions. On shifting, the chain oscillates momentarily and that's when it can fall off. I suspect that stiffer springs may result in smaller oscillation and fewer chain chucks.
    My folding bike photo essays www.dekter.net/

  17. #17
    Eschew Obfuscation SesameCrunch's Avatar
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    Quote Originally Posted by Fat Boy View Post
    I just made an upgrade. I stuck an SRAM X.9 rear derailluer and a X.0 shifter. The problem I've been having with the chain being thrown just went away. I'm convinced the stock JUJU derailluer is pretty much a P.O.S. I stuck the new derailluer on and, just so you know, the stock shifter doesn't use the SRAM 1:1 ratio, so I had to get a new shifter. I got last year's X.9 and X.0 pieces pretty cheap.

    The difference in the bike is _huge_. It reminds me of when I went from an STX setup to an XT setup many moons ago. There's no more chain throwing or false shifting. It's not a cheap upgrade, but it's definitely worthwhile.
    Reminds me of when I upgraded a DT Front Suspension bike to SRAM X.7 shifter, RD, cassette and chain. Shifting became a thing of beauty.

  18. #18
    Wheelsuck Fat Boy's Avatar
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    The spring tension on the SRAM piece is much higher than stock JUJU. The shifts are much crisper and quicker.

    I went for an hour ride earlier this evening. I got to hit a little single track. Honestly, I probably shouldn't have. At first I was just on fire-road. That was OK, but got a little hairy. The stock tires are really good for streets and roads (what I ride on the most by far), but it gets _real_ lively at speed on loose stuff.

    I ended up eating it on the single track stuff pretty good. In all honesty, some of the stuff I was on would have been a little hairy on a real mountain bike. On my DT you'd have to be a better rider than me to make it without going down.

  19. #19
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    Last month I bought a closeout Downtube IX. I already have a Dahon D7. We had two grandkids visiting, and wanted another bike so we could all ride together. To that end, the IX is fine-especially at the price of $299 (IIRC). As a folder, however, the IX leaves a bit to be desired. It folds into a heap that is bigger than the D7, and there's nothing to hold the bike together when it's folded. This makes carrying the folded bike problematic. My wife and I took a bike/bus trip downtown, and the bus driver HATED the IX, having some words with me about carrying on a too-large item (the D7 folded neatly and stowed under a seat). He also didn't like the way the IX's handlebars fold on the outside of the bike, thus exposing more parts for passengers to accidentally trip over. The D7's handlebars fold between the wheels, thus not leaving them exposed when the bike is folded. On our return trip, I put the IX-unfolded- on the bike rack on the front of the bus. This worked fine, but seems to defeat one of the reasons for having a folder in the first place. I can't speak directly about riding this bike, because at 5'11" I can't raise the seat high enough to ride comfortably.

    So...as an extra bicycle that can accommodate a variety of people (kids through adults), the IX is good choice. In this case, keeping it folded until needed is fine if one uses a strap or a bungie cord to hold it together when folded. As a folder for people who commute, and need a bike that folds compactly and can be carried on rush-hour buses/trains, this ain't it.

    We've wondered if the IX could be sold in a non-folding version. In this way, it'd be a very affordable addition to a multi-bike household. Again, as an extra bike that can accommodate people of different heights without costing a fortune, this is a good choice.

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