I have an TruVativ Stylo Team crankset.

Bought a FSA 36t chainring to replace the 32t middle ring and a bash-guard to replace the large chainring. Simple, right?

The ramps for dropping the chain down on the FSA chainring are larger than the TruVativ it replaced. This causes the chain to rub against the ramps of the FSA ring when the chain is on the small ring and 4h or 5th gear in the back.

I tried spacing the small chainring out with 1/4" washers (hole size, not thickness ). No more rub on the ramps of the middle ring when the chain is on the small ring across all the gears of the cassette. Good. Except the chain can now get stuck between the chainrings. Suck.

Guess I need smaller (thinner) spacers. Home Depot didn't work. Any ideas?

I don't know why this is even an issue. I thought this stuff was standardized.

_________________
Ambition is a poor excuse for not having sense enough to be lazy. ~Milan Kundera

I had the same issue when I replaced my big chainring: middle chainring + small cog and the chain rubs the shift pins on the big chain ring. I just adjusted my shifting to avoid those gear combinations and next time I'll be sure to use TruVativ rings.

My advice is to do the same: leave the spacers out and adjust how you shift to avoid the high chain angles. Not the answer you wanted...I know. Sorry!

_________________
"I never learned anything from winning, it's the races where I got my butt kicked that I learned the most" - Michellie Jones (Ironman World Champion)

http://www.ericpalmerendurancecoaching.blogspot.com

Did you try a FSA granny ring? Beyond being a general rule to replace chainrings together (and rear cassette for that matter) I'm wondering if the FSA granny ring is inheritently spaced differently and designed to work with the FSA middle ring. Just a thought.

Very good idea Brian. Yes, I tried replacing both, no change. I think the spacing between rings might be different between TruVativ (narrower) and FSA (wider) cranksets, so the ramps are more prominent on the FSA to drop the chain over a wider gap to the smaller ring. At least that's what I suspect would make sense. Unfortunately, the washer I tried as a spacer makes the gap just a little too wide. No more rub, but the chain can drop between rings and seize.

Need something thinner as spacers. Meantime, back to using the TruVativ 32t middle ring.

I wonder which camp Shimano is in, that is can Shimano rings be used on TruVativ or FSA cranks?

_________________
Ambition is a poor excuse for not having sense enough to be lazy. ~Milan Kundera

It could simply be the larger diameter of the 36T ring that is causing the problem. For one, if the chainline is not optimal what was not a problem with 32T could become one with 36T. When the chain is running to the cassette at a slight angle it would be more likely to contact a 36T chainring than a 32T, because the edge of the larger ring would extend out further. This is especially true if you kept the same size small ring. A matched setup like 22/32/42 will normally work better than something like 22/36 as its an easier gap to jump. A larger small ring would have the opposite effect of the larger middle ring.

Two possible fixes are adding or removing a spacer from the bottom bracket, and/or using a larger small ring.

Check your chainline first. Keep in mind if you are going from triple to double ring the chainline setup can be different as you will no longer need spacing to accomodate the 3rd ring. With the chain on the middle ring the chain should tend to be at more of an angle when shifting onto the larger cogs at the back. On the other hand, from the small ring the angle should be greater for the smaller cogs. If either is not the case then you can add or remove a spacer from the bottom bracket to improve the chainline. Spacers are usually 2.5mm and can be had at any shop.

The other thing you could try would be to go a larger small ring - 24T might work better with a 36T ring because the chain will be at a higher point relative to the edge of the larger ring and might not contact it as easily. It still might, but not until one of the harder gears (which you wouldn't want to use with the small ring anyways).

I've seldom been able to set up a drivetrain so that there is no rub in all gear combos. With tweaking you should be able to set it up so that there is none in the combos that you want to be using.


edit - I've used shimano, raceface, FSA, probably some other brands with different types of cranksets. They should all be interchangeable - at least, I've never noticed problems by changing brands. The only problems I've had come from using larger diameter rings or mistakenly trying to use ramped rings with single ring setup or non-ramped with dual. They should work fine, I would think.

No. I tried that and the inner diameter on the Shimano rings doesn't fit the TruVativ cranks.

_________________
"I never learned anything from winning, it's the races where I got my butt kicked that I learned the most" - Michellie Jones (Ironman World Champion)

http://www.ericpalmerendurancecoaching.blogspot.com

Thanks evedog! I hadn't even considered the chainline. This makes good sense. Will check on that tonight.

I was able to get the FSA 36t and FSA 22t to work well after some adjustments in my living room (Note- as per Brian's suggestion- only the FSA 22t worked through most of the cassette. The TruVativ 22t appears offset, the FSA is not).

That is until I took a ride. The combo of the small chainring and 4th cog down on the cassette would sometimes get the chain to jam between the chainrings. I guess it begin to ride into the higher chainring for this to happen? This surprise usually occurred only when in that gear combo and when under stress. I didn't try higher gear / smaller cassette cogs while in the granny- probably should have. I could generally feel it binding up and could back-peddle before jamming it completely between the chainrings.

EDIT: Got home and checked it out. Yup, when the chain is in the granny and shifts to the lower cogs (3rd and 4th) in back, the chain angle is causing it to get picked up by the shift pins of the 36t chainring. Thus the chain moves to jam between front rings.

As Evedog rightly points out, the geometry of a smaller (32t) ring would allow more clearance than a larger (36t) middle ring for the chain. A triple ring chainline would be different from a double (converted from triple!) chainline. Hope it works, for both Zippy, myself and other TruVativ users. Thanks Evedog.

_________________
Ambition is a poor excuse for not having sense enough to be lazy. ~Milan Kundera

Okay, Evdog had it nailed- the chainline.

I took the spacer off the non-drive side and put it on the drive side. Found another spacer from an old bearing set and put that on too. So 3 spacers drive-side.

Now the chainline looks as though it passes from the middle of the 2 chainrings to the center of the cassette. The granny shifts to all but the highest 2-3 cogs, and the 36t shifts to all but the lowest 2-3 cogs out back. Nice!

Thanks Evdog!

Only issue may be having 3 spacers on he drive-side which I heard may impact bearing wear.


So anyone converting a 3-ring to 2-ring set up, and increasing the size of the middle ring, be aware of the effects on the chainline.

_________________
Ambition is a poor excuse for not having sense enough to be lazy. ~Milan Kundera