Hi apologies in advance if this is a dumb question, very much an amateur trying to learn and do my own bike maintenance.
I bought a new set of chain rings for my Giant TCX, going from the 46/36 that it came with to a 50/34. Just installing them and the big ring is very close to the frame, during installation before all bolts were tight then some of the teeth were scratching against the frame and this has marked the teeth (and the frame but it's not immaculate to start with!)
Now all the bolts are installed the teeth aren't touching the frame but are within 1mm.
Is this just not compatible with this frame? Or is there another adjustment I can make to make it fit? Or ok and I'm overthinking it?
TIA
by BittsrOtter
14 Comments
You might have totaled the frame there. Hard to tell but if it’s more then paint damage, the frame is no longer safe to ride.
These are a bit too large. Try smaller ones or maybe play around with a spacer around the axle. Is the frame carbon? You may have an issue there. Aluminium or steel? Don’t worry.
Definitely too close for my taste.
But could you do me (and yourself) a favour and run a string from one dropout around the stem and to the other dropout? Are the distances to the seattube the same on both sides? Picture 2 looks like the answer might be “no”.
I do not believe you will be able to get a chain safety around that chainring. Don’t risk an accident.
Yep, size back down and follow manufacturer specs.
Think of the added width of the chain. Yes, it is far too close.
5 sheets of paper is the minimum clearance according to ronny romance. At least on metal frames.
But if you want more clearance you can shim your BB cups. usually when you buy a BB there are 3 shims included which you can put on either side of the BB cups. Try putting one on the crank arm side so you get more clearance. If there is a shim on each side currently, move them both to the drive side.
edit: doesn’t look like your BB has shims. Is this a 19mm FSA BB? those are hard to find, i was referring to standard shimano 24mm BBs.
Definitely too large. I think 6mm clearance is the guideline most brands use. With the TCX being a cross frame, they have likely compromised on chainring clearance to increase tire clearance.
If that is a GXP style crank, you can’t really put a spacer on the axle. You could space the chainring out, but that will completely wreck your front shifting.
If you want to run a bigger chainring, you probably need a crankset with a wider chainline, which you’ll generally find on gravel cranksets. But I’m not sure you’ll find one that will support those chainrings, as most use newer chainring standards…
50t is larger than recommended for a cross bike, so while you could play around with the BB spacing, you’ll then find the chainline will be off. Plus the amount you’ll have to space it out to make is safe and allow for flex. I’d imagine you’d have a hard time making this acceptable.
And that’s without even getting into whether the front mech will have enough adjustment to clear the 50t. Often cross frames won’t.
There is barely any gap between the frame and chain ring. You are supposed to be able to fit a chain on that chain ring. I don’t see that happening.
Sadly your frame wont let you use larger road chainrings only gravel spec. Pretty tight they do this.
Definitely too close. You might be able to get away with installing a 0.7mm-1.5mm spacer on the crank side and see how that goes? You have a square Bottom bracket from the looks of it. and if that doesn’t work then upgrade to a Hollowtech BB+crank. Under $200 upgrade.
Put the 46 back on for now so you can use it.
Depending on the type of bottom bracket, can put a spacer between the bottom fixed cup and frame to move the crankset out a little further. Is this all original BB and crank?