masi61

So I’m working on a pretty cool 3 x 8 drivetrain on my 1999 Cannondale R1000 that is made up of Suntour shifting components.

I’m using SunTour “Command” 8 speed butterfly thumbshifters. The rear derailleur is an XC Pro short cage and it shifts really well with my Suntour “AP” 8 speed cassette.

Previously I had a Dura Ace 7410 double crank with 53, 39 Salsa chainrings shifted by a SunTour Cyclone 7000 front derailleur - it shifted fine.

Then I decided to turn the crankset into a triple using a Willow triplizer. The chainrings are now: 53,46 & 32. My bottom bracket axle went from a 103mm to a 115 mm to accommodate the 32 tooth granny and clear the chain stays. I couldn’t get the range I needed on the Cyclone 7000 front derailleur to let the cage come out far enough to not rub in the 53 x 12 big gear so I put a SunTour XC 9000 front derailleur on there. It does have the range.

But I have a new problem: it can’t quite push the chain from the 46 down to the 32. I have the low limit screw set to allow no rubbing in the 32 x26 low gear. If I give extra room on the inside by opening up the limit screw more, well then it drops the chain.

So what I need to know is: how can I get this to shift reliably to the 32 chainring yet not drop the chain? Please help!!

Eggman84

According to Sheldon Brown "Rotating the derailer so that the back of the cage is farther out will sometimes improve shifting to the small ring of a triple by preventing overshifting, but may cause increased need for trimming on the larger rings. It may also cause the crank to strike the cage." https://www.sheldonbrown.com/deraile...ent.html#front

If overshifting is a problem, you can also add a chain watcher like https://www.universalcycles.com/shop...ls.php?id=6716

Setting up front derailleurs for triples can be very frustrating and time consuming. For 3 years, I had problems shifting to the large triple ring; either was VERY slow or overshifted. I finally realized that if I just slightly bent the front of the inner cage outward (narrowed the space between the plates by about 1/16"), that it would push the chain onto the large chain ring without upsetting any of the other shifts. Works perfectly. Why it took 3 years???

Good luck.

masi61

Thank you!
I'm going to try pivoting the cage outward as you suggest.
I did just go and order an inexpensive "deflector/drop watcher/guide/keeper" in the 31.8 size I need from eBay for $5.87. Who knows, maybe I won't need it.
Anyway, I will post an update on how (and when) I got it to work.
3 years for you to dial in your set-up does now surprise me by the way. My Ultegra 66603/6503/Dura Ace 7703 set up took about that long for me as well.

HillRider

+1 on the chain watcher. I've used both the Third Eye Chain Watcher and the N-Gear Jump Stop and both have worked well. There are also others such as the Deda Dog Fang but I don't have any experience with it.

You set them up so they run as close to the granny chainring as possible with just enough gap for the chain's inner plates to clear. You can then adjust the shifter and front derailleur inner limit screw to give a solid shift but the chain won't (can't) fall off the inside.

masi61

Excellent!!

By the way, i have also seen a type of chain deflector that seems to be an outrigger that mounts to the bolt on a braze-on front derailleur. I'm not sure precisely if these have one specific application such as extra large chainrings for time trials or what. This type ONLY seems compatible with braze on though.

dsbrantjr

Excellent advice, I pre-emptively put Jump Stops on my bikes. As much as I obsess about keeping my drivetrains adjusted, things do happen, and I hate digging a greasy chain out and re-railing it.

masi61

The Jump Stop looks like a nice design. Not sure if these are still made or not. I real excited about this drivetrain not just for the funky, versatile gearing that it will have but also because I am switching over to "Molten Speed Wax". I've got my whole drivetrain, spin-n-span so to speak with the Wippermann chain having a nice coating of the chain wax. It is great that you can touch the chain and not immediately get filthy black oil all over you.

ThermionicScott 

One other tip to help prevent throwing the chain to the inside: don't wait until you are in your 26T bottom cog to downshift to the granny ring. If you are still somewhere in the middle of the cassette, the chain will be running at an angle when you shift to the granny, so it will be less likely to go too far.

dsbrantjr

Their Web site says they sell direct and will ship to USA free.

masi61

Good advice. I tried this, and unfortunately it gives the same result right now. Chain just not quite shoving over down to the 32 tooth.

ThermionicScott 

Hmm, have you ruled out cable friction? Like, if you set it up so that it just fails to shift into the granny after being on the middle ring, can you then press on the FD while turning the cranks to get it to shift successfully?

masi61

good suggestion, I just checked & friction not really the issue as the cable is running smooth. It just appears that (in the application) for the outer front derailleur to have enough "push" to get the chain over to the granny ring - I'm going to have to adjust the low stop screw further inward. Unfortunately this then sets up the situation described where I am now throwing the chain onto the bottom bracket shell.

dsbrantjr

A good chain catcher will eliminate the chain throwing, there is simply no where for the chain to go.

maddog34

"3x8" ... der, is old school suntour,,, from before 8 speed, mostly.....

CHAIN WIDTH is the main difference...

reset the width of the FRONT DERAILLEUR CAGE to compensate... Narrow it up a millimeter or so... work carefully, lest the cage get bent in the wrong amount or direction... the area the chain is nearest when in the middle ring will need the tweaking most...

now, with that solution proposed... you ever notice all those odd bends/steps in the cages of modern 3x front ders.? they are there for more than great looks...... they are shift aids.....

masi61

The chain I’m using is a Wippermann which for 8 speed, will need to check the model but it shifts the rear perfect. I do have a few triple Shimano front derailleurs in my stash for 31.8 (fd-6603, fd-7703, fd-7803). They definitely have much more complex, contoured cages. I believe they were guaranteed to only work perfectly with specific chainring combinations such as 53-42-30 or 52-39-30. The funky combination of 53-46-32 That is being tried here might as well just stay all SunTour for now. I’m hoping that the chain catcher I ordered does the trick.

shelbyfv

It does sound as if the derailleur cage is too wide. However, a more modern triple will likely not clear your large middle ring. The jump stop will probably let you live with less than optimal adjustment but I'd still try angling the cage or putting a little bend in the front.

bradtx

masi61, Is the chain derailing cleanly and easily from the middle to inner chain ring? Is the inner chain ring dished on one side?

Brad
PS. And some thought I was odd to change my '99 R1000T to bar ends.

masi61

HaHa - yes you are odd & so am I. A ‘99 bike is practically in the realm of “classic & vintage” now anyway. I purposely built this up as a bare frame from day 1 as a vintage SunTour build. It has always ridden really nice. The polished hubs (Superbe Pro 8 cassette rear, XC 9000 front) look bling-y in a bygone way...

As to your question re: how cleanly am I transitioning from middle to small chainring - I’m not shifting over at all right now. It’s just rubbing on the thin middle part of the outside of the XC 9000 front derailleur.

This was purchased last week & is “new old stock” condition, I really have no plans on monkeying around with the cage. The outer arc seems sufficient for the 53 tooth big chainring. Also, the cages on many of the SunTour front derailleurs I’ve run across has some old school contouring of its own. For example, while the outer cage lines up parallel to the chainring, the inner cage has a helpful inward, pigeon toed bend to it. This feature speeds the release from the big to the middle ring. (Correction ... I had to think about this, the opposite is true. The toe in of the inner cage aids in the smooth push from the middle to the big ring. Basically upshifts into the big ring are heavenly). Honestly, I couldn’t ask for more, the retrofriction action on the Command front shifter is just that good.

I have a Puch Marco Polo set up as a touring bike with SunTour Superbe Pro 7 speed down-tube shift levers. My crank is an older Specialized road triple with 53-42-30 rings. The front & rear derailleur are SunTour X-1. The front shifting is fine as I recall. The bike hasn’t been ridden in a few years due to the frame size being 25” (~64cm!) where I now enjoy compact frame geometry. I guess it’s going to have to be deployed in the name of a drivetrain check!

bradtx

masi61, I would try raising the FD a couple mm to engage the chain a little aft.

Brad

masi61

Is raising the cage going to engage more of the bottom of the cage as it shifts from the middle to the granny? This is worth a try since the middle (46 tooth) chainring is a little taller then average. I will try it then post results here.