JWK

I'm changing out components on a GT Grade gravel bike. I've got the FSA compact crankset off (surprised to see they still used a tapered square BB), the brifters, cabels, etc. Please keep in mind I've never changed out component groups like this before.

So now I'm ready to install the 5703 crankset. I got a 6800 BB along with it with my order since the 5700 BB was no longer available from Chain Reaction. So I start reading about installing triples and I figure something is wrong. Long story short is that I thought I didn't need any spacers because the Chain Reaction site stated the 5703 has a chainline of 43.5mm. The 6800 BB is designed for a chainline of 43.5mm, so I thought great, I don't need spacers. Wrong. I found the Shimano pdf and it clearly states that the 5700 crankset has a 43.5mm chainline and the 5703 has a 45mm. As I just found in the Sheldon Brown site, this is standard.

So now to confuse me even more, the Shimano pdf for the 5700/5703/5790 cranksets states a spacer and ring is needed for the left (non DS). WTF?! Nothing said about the drive side.

I have done as much research into this as I know how. According to Shimano, I need to end up with a 45mm chainline. I have the typical 31.8mm seat tube. Can anyone tell my what I need to get and where to get it? Why is there a ring and spacer needed for the non-drive side? What the heck is the difference between a ring and a spacer?

Thanks for any help and info.

Side note: Thanks to the help on my last post earlier in the year, I got a 24t inner ring installed with the proper SS washers to give the teeth the same spacing from the middle ring. I really appreciate the help I get here!

trailangel

You need a ruler that measures millimeters.

Bill Kapaun

Have you stopped and thought about how much difference 1-2mm is going to have?
If your chain is running perfectly straight on ONE cog, it won't on all the others.

2lo8

Just follow the Shimano instructions and ignore the part that was probably copied from the double by the retailer.

JWK

I posted that I read the Shimano instructions and that they don't make any sense to me. It states the 5703 needs a ring and spacer on the non-drive side. It says nothing about the drive side or how you get the 45mm chainline the same sheet says you need for the 5703. It also does not state what spacer or ring you need. Maybe they came with the 5700 BB, but those I cannot find.

2lo8

You don't need to make "sense" of the instructions. Just follow them. You don't use the BB to adjust chainline. That's to correct for bottom bracket shell width on MTBs. The cranks need their specified spacers to achieve their specified chainlines, so use them as specified. The tech docs say there is a 3mm spacer NDS and a 6.5mm spacer DS.

jimc101

Look at the EV here SHIMANO Dealer's Manual / User's Manual no need to read anything, copy the EV and it will work.

All this talk of measuring chain-lines is (for external BB purposes) obsolete, the manufactures supply the parts which are effectively fit and it works out the box, much simpler then the square taper days when chain-line was more critical.

Mr IGH

I have that crankset on my 68mm bottom bracket shelled frame. I didn't use any spacers.

shelbyfv

I think the crank will give you the correct chainline. It's so easy to install the new BB and crank. Try it and see.

HillRider

That is correct. The crank itself will give you the correct chainline as installed and no drive-side spacers are provided or required. The 5703 does use a spacer (provided with the crank) on the non-drive side. Follow the instruction sheet and it will work fine.

dedhed

file:///home/chronos/u-71c0988f1649b1a49d367c58f9d512f2c860aba7/Downloads/EV-FC-5703-3004B.pdf

https://www.bikeforums.net/bicycle-me...m-bracket.html

JWK

OK, thanks for all that info. I took a better look at those docs and looked up the components again on the Shimano site and found that the ring and spacer is included in the crankset, not the BB. Sure enough, at the bottom of the box there was a little plastic bag with the non-drive side spacer and the crank arm fixing bolt. However, there is no ring that is supposed to go between the spacer and the BB. All the instructions include this ring as part of the assembly. As far as the drive side 6.5 spacer, it looks like it's on the drive side already. The diagram shows the BB and the crankset together with all parts listed as if it's one unit. I'm assuming the BB shown is the 5700. Maybe the rings (both sides on the docs show rings) came with the 5700 BB but they're not necessary with the 6800 BB that I have. Just guessing.

I'll put it together and see if everything seems to fit right and go from there. Thanks again for the help.

HillRider

The instructions show the ring as a separate item but it's really part of the larger spacer and already snapped into the side that faces the frame. I had the same question when I installed my first 5703 crank but the ring is there.

JWK

OK! Now that I'm looking at it, I see exactly what you mean. With no experience at all, it seems a lot more complicated and confusing at first than it really is. Now it seems very simple and straight forward.

Thanks again, HillRider.

GeoKrpan

Thanks a lot. I had exactly the same dilema as the OP. Now it is perfectly clear to me.