I’m trying to fit a chain device (e*13 DRS) to my Blur LTc and it’s going to involve some serious modification to the device, I can reduce the amount of work involved if I fit the drive side BB spacer between the back plate and the frame, but this will obviously move the chain line out by 2.5mm

Will this have a detrimental effect on the drive train?

Is this chain device fitting by BB mount or ISCG?

Try it and see if you have any problems. I’ve spaced quite a few of my bikes over the years. Some resulted in frame rub and some were fine.

The chain device is a BB mounted one

You can also buy thinner spacers.

i did this on my specialized enduro a couple of weeks back, i couldnt get the guide anywhere near close enough to the chainring so i took the bb spacer out and chucked it. as long as the cranks dont hit the frame at any point during the travel, your cranks tighten up ok so theres no lateral movement (or in your case of adding more spacers, that theres still enough thread to connect up your cranks securely) and it still feels ok to pedal, i cant see the problem. helped to sort my issue right out.

In my experience (based on a 456 and Soul), I had to move the chainline inward when I converted to single ring up front. With that in mind I can’t imagine moving it out by 2.5mm will do it much good, but of course that depends on the frame and crank.

cheers for the replies guys

The BB mount would replace the equivalent amount of spacers on the drive side, not used in addition.

Without knowing your exact setup, if you have converted a triple crankset to single, the lugs the granny ring mounts on to can sometimes interfere with the bb mount in which case you may need an additional bb spacer to create clearance/file down granny ring mounts.

Maybe I am misunderstanding your trouble though.

Edit: nevermind, re- reading your OP I guess it’s swing arm clearance related. Different chain device? I use an inner+outer bash ring sandwich with clutch mech and it’s yet to jump. But I’m not doing DH type riding.

when people say they add or remove BB spacers I assume you are keeping the total effective BB shell width the same by adding or removing spacers on the non-drive side to compensate?

If you don’t you risk messing up your cranks/BB.

Andy, this is what I was getting at.

Due to the swing arm it’s pretty much impossible to mount the back plate flush against the frame but I have managed to get the back plate mounted (still after lots of grinding and filing) by using the BB spacer so I have increased the overall BB length by 2.5mm.

How will this mess up the cranks/BB?