Chainring replacement oh no!
 

Just replaced the cassette and chain on my Specialized Crosstrail Elite Hybrid 2016 and ended up with a set of noisy chain rings under load. Here is the symptom as stated on another thread.


https://www.bikeforums.net/bicycle-m...-so-noisy.html


So I went to my local LBS to get a Small 64 BCD 32T chain ring and a Large 104 BCD 44T chain ring. I put them both on and found out that the large chain ring hits the chainstay after tightening down on the bottom bracket taper. The crank is a Samox 2X10 44/32. Here is a link to the large chain ring:


https://www.amazon.com/Truvativ-Chai.../dp/B006M4KG52


The only response from the LBS is to keep the large chain ring I have and just replace the small one. That does work. But I really would like a new large chain ring. The problem is tied to the original chainring that has a 4 MM offset to the outside while the new large chain ring is flat. Here is a link to a set of pictures with the old large and new small chainring installed, with the new large beside it. As you can see this offset of 4 MM is what I need in a new large chain ring. LBS was really not interested in going any further. I have replaced everything on the drive train except the large chain ring. Any ideas on how to solve this? New crank? Searching on line is quite difficult just by looking at the pictures for chain rings.


https://www.dropbox.com/sh/0qsokotn8...6M0lsTWBa?dl=0

Try to find an identical replacement. If they are made as OEM equipment for your bike, there are undoubtably replacements available.

Longer bolts and spacers

When using the large chain ring I had to use spacers on the small chain ring(4 MM) to get it in correct position since the large chain ring is 4 MM closer to the frame. I would have to mill the crank on it's spider connectors to move the large chain ring out.

What you just discovered is there are no longer any standards in bike parts. Stronglight 49d crank was shown in 1932, fully marketed in 1934 and manufactured with no changes for almost 50 years. There are currently several copies of that crank being sold still (Sun XCD, Velo Orange, maybe more) and you can get chainrings easily. In fact you can use steel chainrings made before 1932. When marketers want to introduce new and unique configurations every day of the week lots of orphan parts happen. Try not to buy that kind of junk. Often you won't know in advance you have an oddball part, in many market segments you don't even have a choice to buy standard parts.

LBS could spend a lot of time and get nowhere on this one. They see it every day and usually have no good choices. Parts distribution is a train wreck. You could try to contact Specialized yourself. I'd not even know where to look to find if Samox is a real company or a name used once.

the spacers would go on the big ring side but if you need to shift it 4mm to miss the chain-stay then that is too big a jump between the rings, was the original 32 tooth ring scalloped to match the big ring? I would look at how much the crank needs to shift and then consider whether a longer bb would still allow a reasonable chainline and front dérailleur adjustment. Option 2 and 3 would be a smaller big ring or look at new crank and bb options I prefer the outboard bearing type like the hollowtec 2 varieties.

4 mm difference between the old and new chiainrings? That sounds really high. Did you take the crank off to change them? Tighten the crank tighter than it was before when you put it back on?

Now the deed is done. You can add a spacer inside the fixed cup and move the whole BB out a bit. A few of us have brought life back to overly forced crank tapers using sheet aluminum (often from soda cans) between the spindle flats and the crank flats. There was a thread recently on doing this. Another option is a new BB with a longer spindle.

If you space out the outer ring; two cautions. You could have such a large gap between the chainrings that the chain falls into it and gets stuck. The end result could be bad. Also you want to make sure that the nut side of the chainring bolts has a sleeve long enough to project into the chainring. It is that sleeve that supports the chainring, not tension from the bolt. If the sleeve isn't long enough, the chairing will slip, the bolt and sleeve will elongate the holes in the spider and chainrings and you will end up needing to replace the crankset. (Not dangerous. Just expensive.)

Went to a different LBS today and showed them my crank and the two large chain rings. Had the chain bolts off so they could see the setup with the new large chain ring and the old. The conclusion was to move to a new BB like the Hollowtec and dump the BB taper. So, tonight I put it back together with the old large and new small chain ring and all is back to normal shifting. The new small chain ring is quiet and the old large has some noise under load. Going to begin the process of moving to a new type of BB.

Thanks for all the comments!