Folding Bikes - Upgrade DownTube derailleur from Juju to What?

I'm pretty happy with my DownTube (FS IV 2007) folder, but the rear derailleur seems to be a weak point for me. It has a long cage that is less than 2 inches off the ground, and I can't keep it from skipping gears and throwing the chain occasionally. I'd like to upgrade to a medium cage derailleur, but I'm confused about compatibility - can anyone suggest a good upgrade derailleur?
I believe the Juju M90 is high-normal, so that rules out Shimano, but SRAM seems to have a proprietary 1:1 actuation ratio. Also, the rear cluster is 11-32 and many derailleurs seem to handle 28t at the largest. Finally, will I need new shifters or can I continue to use the Juju? I'm definitely confused - Help???

Thanks,
-J.R.

I'm no tech expert but I'd have thought the Downtube can take pretty standard configurations. I haven't had any experiences with the chain throwing but I do find the bike geared somewhat on the low side and the range would improve by changing the cogs to a larger T set.

If I was going to upgrade, I loved the Shimano Deore with the trigger shifting mechanism that I used to have on my Specilaized Crossroads 2006. Great gears with such a smooth and precise change. Trigger shifter was great too.

I'm pretty happy with my DownTube (FS IV 2007) folder, but the rear derailleur seems to be a weak point for me. It has a long cage that is less than 2 inches off the ground, and I can't keep it from skipping gears and throwing the chain occasionally. I'd like to upgrade to a medium cage derailleur, but I'm confused about compatibility - can anyone suggest a good upgrade derailleur?
I believe the Juju M90 is high-normal, so that rules out Shimano, but SRAM seems to have a proprietary 1:1 actuation ratio. Also, the rear cluster is 11-32 and many derailleurs seem to handle 28t at the largest. Finally, will I need new shifters or can I continue to use the Juju? I'm definitely confused - Help???

Thanks,
-J.R.

I think you need to parse out your problems individually to resolve them properly. It seems you're describing 3 things you're not happy about - 1) long cage being close to the ground, 2) skipping gears, and 3) chain drops.

1) You don't say whether the 2" clearance is causing you problems, but if you do want to switch to a medium cage, you'll be fine with the 11-32. I'm using one with 11-34 cassette. The specs are often conservative, as you probably know. Shimano RDs will work fine. Deores go for about $25 I think.

2) Skipping gears - Are you sure your RD is properly tuned? New cables often stretch after a while, and a very simple adjustment will bring the RD in proper alignment.

3) Chain drops - I'm assuming you mean it drops off the front chainring. Do you still have your chainguard on in the front? Chain drops happen more often with folders because the wheelbase is typically shorter. Therefore, the chain leaves the chainring at a more severe angle than with standard bikes. So, it is more vulnerable to drops. There are aftermarket solutions to preventing this. Some of the guys here have purchased little rollers that sit on top of the chain to solve this.

.... It has a long cage that is less than 2 inches off the ground, and I can't keep it from skipping gears and throwing the chain occasionally.

Is the < 2" from the ground a problem?

If so, I am amazed, because I thought some time ago that derailleurs were pretty crude & that low clearance was bound to cause a problem, but my experience is that yes, they're primitive, but work just fine, & in awful weather, & poor road surfaces. I've never had a problem riding rough surfaces with low ground clearance, so I'd be interested to know what conditions you find that a problem!

We've had lots of floods over here over the last 2 years & it's unclear to me how well hub gears would cope in such conditions.

Can you expand on "high-normal" & "actuation ratio" please?

There are some videos on Youtube et al, explaining gear cable adjustment.

Chain throwing may be a result of sticky chain links, perhaps after heavy rain? (No idea where you cycle)

I think you need to parse out your problems individually to resolve them properly. It seems you're describing 3 things you're not happy about - 1) long cage being close to the ground, 2) skipping gears, and 3) chain drops.

1) You don't say whether the 2" clearance is causing you problems, but if you do want to switch to a medium cage, you'll be fine with the 11-32. I'm using one with 11-34 cassette. The specs are often conservative, as you probably know. Shimano RDs will work fine. Deores go for about $25 I think.

2) Skipping gears - Are you sure your RD is properly tuned? New cables often stretch after a while, and a very simple adjustment will bring the RD in proper alignment.

3) Chain drops - I'm assuming you mean it drops off the front chainring. Do you still have your chainguard on in the front? Chain drops happen more often with folders because the wheelbase is typically shorter. Therefore, the chain leaves the chainring at a more severe angle than with standard bikes. So, it is more vulnerable to drops. There are aftermarket solutions to preventing this. Some of the guys here have purchased little rollers that sit on top of the chain to solve this.

Thanks very much for the advice.
1) The 2" clearance hasn't caused me any problems yet, but it seems like a vulnerability I can eliminate with the right upgrade. To use a Shimano RD, do I need to replace the Juju shifter?

2) Well I'm no expert mechanic, but I use the barrel adjuster to correct shifting from highest to low gears. But when I'm pedaling under load, sometimes the middle gears skip. I don't think the hanger is bent, but that's just by eye.

3) I had removed the chainguard from the front thinking it was unnecessary - I guess not. But it did seem like some people on the list reported that the tighter springs of better RD kept the chain on.

Is the < 2" from the ground a problem?
Can you expand on "high-normal" & "actuation ratio" please?


I thought derailleur compatability was an issue between brands. From my internet research, I discovered that "high-normal" derailleurs "rest" at the highest gear and are pulled toward the low gears by the cable. "low normal" work the other way. The Juju appears to be "high-normal," but I thought shimano were low-normal - so incompatible???

Then when I looked for SRAM derailleurs, I discovered that the amount of cable they pull for each gear change is different than Shimano's (the actuation ratio). So, which one is right for the Juju shifter????

I'm obviously confused still, though because people on the list report success with both. Unless the answer is that I must upgrade the shifter at the same time as the derailleur.

You would be better off upgrading the whole set say to Shimano or SRAM. It is not en expensive upgrade.

You would be better off upgrading the whole set say to Shimano or SRAM. It is not en expensive upgrade.

I would say the same thing. I switched to SRAM X.7 RD and thumb shifter, and it was fantastic! Not that expensive either. I felt so confident with that combo. Shifting was absolutely precise and fast.

Also, part of your gear slippage problem could be the twist shifters that come with the bike. I found early on that I was inadvertantly twisting the grip shifters as I rode and that caused gear slippage. Hence I switched to thumb shifters. Huuuuuge difference.

I would say the same thing. I switched to SRAM X.7 RD and thumb shifter, and it was fantastic! Not that expensive either. I felt so confident with that combo. Shifting was absolutely precise and fast.

Also, part of your gear slippage problem could be the twist shifters that come with the bike. I found early on that I was inadvertantly twisting the grip shifters as I rode and that caused gear slippage. Hence I switched to thumb shifters. Huuuuuge difference.

I agree about the twist grip, this is interesting as I have had issues with the shifting because of it. I totally endorse SC's advice lol. Anyway, Sesame is one of the resident Downtube conversion expert and had already upgraded the juju set. :)

Within weeks of getting my DT IX I switched out the RD and shifter. I had similar skipping problems, plus it just wouldn't stay in alignment. It was hard to tell for sure, but it appeared that the Juju cage had been bent in shipping. The RD hanger had been bent for sure, but Yan sent me a replacement. Still, it did not work quite right.

I also chose to upgrade to the SRAM X.7 RD w/ a medium cage(couldn't find a short cage) and shifter. Now it shifts like it really should. Plus, I have only thrown the chain once in the last 9 months. While I was at it I also replaced the cassette and chain, but that is probably not necessary in most cases. I did it to assure myself of complete compatibility.

If you are going to ride the bike daily I would definitely recommend an upgrade to either SRAM or Shimano. Both make excellent dérailleurs.

Thanks very much for the advice.
1) The 2" clearance hasn't caused me any problems yet, but it seems like a vulnerability I can eliminate with the right upgrade. To use a Shimano RD, do I need to replace the Juju shifter?

2) Well I'm no expert mechanic, but I use the barrel adjuster to correct shifting from highest to low gears. But when I'm pedaling under load, sometimes the middle gears skip. I don't think the hanger is bent, but that's just by eye.

3) I had removed the chainguard from the front thinking it was unnecessary - I guess not. But it did seem like some people on the list reported that the tighter springs of better RD kept the chain on.

This still could be cable stretch.

I have an 8 speed Downtube and had problems with the shifter. The LBS replaced it (along with the shifter cable) and the bike worked good for a few days. Then the middle gears started missing. Note gears 1 and 8 were fine. I took it back to the lbs and they adjusted it in about 30 seconds and the bike was fine.

I'm not sure what happened, but my theory is that if the stops are set correctly, normal cable stretch will only cause the middle gears to miss.
Take it to the LBS--this might only cost you a $5 adjustment.

The stock JuJu derailler is junk. That's my opinion, but it's an informed one.

I replaced it with a SRAM X.9 short cage (medium would work just as well). When you do this, you have to change to a SRAM shifter because of the aforementioned difference in accuation ratio. I used a X.0 twist shifter.

It works awesome. I haven't thrown a chain since and the shifts are _so_ much better you can't believe it. I spent a good chunk of time trying to make the stock stuff work. It just isn't up to the task.

There are some older threads of mine that talk about what I went through, but it's so much of a better deal after changing that I don't know why it isn't stock. The additional money that it takes to put on something reasonable as opposed to the Suntour trash components can't be that much, and it makes the bike much, much nicer.

I had a used Shimano Dura-Ace rear short cage derailler in the parts box so after reading this thread it just had to go on my Downtube NS.Now the bike shifts great. Jack

And if the Dura-Ace or X.9 works that well, then you can bet that a Deore, Tiagra, or X.3 does nearly as good of a job. Yan goes way back with Suntour, so he probably gets the stuff nearly given to him. Whatever he pays, it's worth less than that, which means it's worth much less than what we pay for it.

I actually think it's a genuine detriment to the bike.

3) Chain drops - I'm assuming you mean it drops off the front chainring. Do you still have your chainguard on in the front? Chain drops happen more often with folders because the wheelbase is typically shorter. Therefore, the chain leaves the chainring at a more severe angle than with standard bikes. So, it is more vulnerable to drops. There are aftermarket solutions to preventing this. Some of the guys here have purchased little rollers that sit on top of the chain to solve this.

Chain drops only happen to me when the chain is dirty. In my area it gets dirty fast, so I have to keep up on it about every 2 weeks.

And if the Dura-Ace or X.9 works that well, then you can bet that a Deore, Tiagra, or X.3 does nearly as good of a job. Yan goes way back with Suntour, so he probably gets the stuff nearly given to him. Whatever he pays, it's worth less than that, which means it's worth much less than what we pay for it.

I actually think it's a genuine detriment to the bike.

A lot of bike manufacturers use OEM crap. My tikit came with garbage components made by a Taiwanese company that only sells to suppliers. I put on a Tiagra and an SRAM rapid fire and got a much better result, but then thought with a sticker price of $1300, why didn't they make it $1325 and give me the better derailer/shifter?

A lot of bike manufacturers use OEM crap. My tikit came with garbage components made by a Taiwanese company that only sells to suppliers. I put on a Tiagra and an SRAM rapid fire and got a much better result, but then thought with a sticker price of $1300, why didn't they make it $1325 and give me the better derailer/shifter?

I agree 100%. The deal with a tikit, though, that if you want to order it with something else, you can. The derailler DT only comes with a JUnkJUnk.

The derailler DT only comes with a JUnkJUnk.

I have the Downtube IX and had to replace the pedals within a week (lousy plastic piece of crap) - The RD hanger was totally bent on arrival so I stuck it in vice and straightened it. I was fully expecting the rear derailleur set-up to fail but 8 months on it's still working fine (It has a faux-carbon look - Woo-Hoo!!!)

Even the tyres are OK. I keep looking at changing parts but as they still do the job I can't justify it (darn it!)

However, I have been informed that cheap aluminium frames do turn to dust in no time so all i'll be left with is the derailleur and tyres.

In London it's actually quite handy having a bike with nothing really worth stealing on it ( I wouldn't leave my Brompton or Moulton outside )

My JuJu is still working 14 months and 1100 miles on. True, I only have 7 usable gears out of 9, and the chain jumps the track once every 10 rides or so, but it's working, but not very smooth at all. It is hard to justify spending $150-200 to upgrade the entire drivetrain on a $300 bike. So far I've spent a total of $81 on maintenance/upgrade: $35 (sealed bottom bracket), $15 (brake noodle and seatpost binding, $21 (new brake pad sets)

I replaced mine with sram X7s, and my GF with Shimano LXs (we both like triggers). Both are long cage, as hers is on a 50t and mine is on a 49t (in hind sight I would have gone with the medium had I known they would be compatible).

I got very tired of the JUJUs fast. They reminded of a nagging hag that needed to be patronized after every ride.

I have bent my hanger more than 8 times since last May when I got the bike.

My first SRAMs... I think I've been converted!!! I could not believe how much the x9 and xOs cost (can be prohibitive especially since you need the 1:1 triggers to match).

The drivetrain upgrade (isis BB, cranks, chainring, chain, sram x7 rears and triggers) has made a huge difference. My GF loves her LX and trigger upgrades.

We both no longer have to deal with that JUJU hag! That alone is worth the upgrades.

My JuJu is still working 14 months and 1100 miles on. True, I only have 7 usable gears out of 9, and the chain jumps the track once every 10 rides or so, but it's working, but not very smooth at all.

Well, I was in a similar state, but a little worse. My chain would jump off the big ring about every 15-30 minutes of riding. I changed the chainring to a 53t, so it was a little worse than stock, but I like the gearing better. I too only had 7 usable gears. Everytime I hit a bump I'd get false up and down shifts due to the derailler not being able to keep up with the suspension.

I bought a derailler for $65 and a shifter for about $50 off of ebay. They were both relatively high end because I didn't want to make the change and _still_ be fighting the same problems. Anyway, it was some of the best money I've ever spent on a bike. It took about an hour or so to change things over and get it set up. I'm really impressed with the SRAM stuff. I just put it on my road bike. I think that you could go with the lower end SRAM stuff or the lower end Shimano and accomplish the about the same that I did for less money. A Deore derailler costs, what, $40? (http://www.performancebike.com/shop/profile.cfm?SKU=21141&subcategory_ID=5111) You can use the stock shifter. I'm telling you, it's a no-brainer. All the annoying stuff just goes away.