Is it possible to get a 54t chain ring for the FSA custom chain set? The current ring looks to be more heavy duty than my current road bike (this might be due to the increased loads) any thoughts on the matter would be appreciated
You may find the following of some use, which relates to the 2016 Road E+1. The frame on the 2017 version was I think virtually identical, but the new 2018 Road E+1 Pro has a re-designed frame, so may have a different chainstay design.
I too find the 50t chainring too small, particularly during non-winter months when I ride quite a bit faster on both e-bikes and non-e-bikes. I therefore decided to investigate the options for fitting a larger chainring.
On close examination of the space available between the 50t ring and the chainstay, I could see it was going to be touch and go whether a larger ring would even fit, due to the way the chainstay flares outwards immediately past the outer ring's teeth. I nevertheless thought there was a fighting chance a 52t ring would fit IF I also fitted some chainring spacers to offset the 52t ring outwards to help ensure that the teeth cleared the flaring chainstay.
It was a very close-run thing, but when I did the first phase of my proof-of-concept testing, I found the 52t ring JUST cleared the chainstay when 1.2mm chainring spacers are used. I severely doubt whether a 54t ring will fit on the 2016/2017 frames, unless VERY thick chainring spacers and possibly longer chainring bolts are used, but have no idea for the 2018 frame which I suppose may have better teeth-chainstay clearance.
Watch out for FSA chainring designs and availability. I could not find any outer chainrings on the internet that visually matched the ring fitted as standard to the Road E+1. Giant shops can source matching 50t/34t sets though, but they ain't cheap. So I went for the
FSA Unisex Pro Road N10/11 110BCD Chainring ('Unisex' - how ridiculous!). However, this has a different (thinner) bolthole thickness and teeth-offset (i.e. dishing) compared with the fitted 50t ring, meaning the use of chainring spacers of some kind becomes essential anyway.
For this experiment, I established that 1.2mm was the minimum spacer thickness needed to clear the chainstay. I haven't actually ridden the 52t ring yet, as I only tested clearance in the workstand before removing the 52t again for the winter, so don't know how shifting between rings may be affected by changing the ring separation. I'm not too bothered if shifting is compromised, as I only use the 34t ring for 10 metres at the start and 10 metres at the finish of my commute, spending the whole of the ride in the big ring, even the steep hills.
I may of course find, when I eventually test-ride the 52t set-up, that whilst the teeth cleared the chainstay during static testing in the workstand the forces going through the chainset during riding may flex it enough to mean the teeth do make contact with the chainstay, in which case switching to thicker (e.g. 2.0mm) chainring spacers may provide enough clearance. I've got various sets of spacers from SJS Cycles to play with:
chainring spacers
If you do experiment, please report back on the results!