tomgdaly

My wife has a Liv Avial fitted with Shimano 105 compact, and I believe it has a press-fit bottom bracket.
She wants lower gears so is there any 'plug-and-play' option, without having to change the bottom bracket etc?
I have been looking it up on-line but, frankly, I'm bamboozled with all the bottom-bracket standards,.
There seems to be room to slide down the front deraileur a little bit.

dsaul

If you don't mind going Oval, Absolute Black makes sub-compact rings to fit Shimano compact cranksets. https://absoluteblack.cc/oval-sub-co...for-110-5-bcd/

wsteve464

According to the USA site for the Liv Avial, can't access Ireland's site without accepting cookies, the bottom bracket is a threaded BB. So it s/be a standard 68mm wide english threaded bottom bracket, the most common type. You should not have a problem finding alternate cranksets.

If you can't find smaller chainrings considered changing the rear gear set for a higher tooth count set, probably cheaper, max size will depend on the rear derailuer model, spec for the RD can be found on shimanos site.

tomtomtom123

If the BCD is 110mm, then the smallest chainring you can put on it is 33T. If the BCD is 130mm, then the smallest chainring that you can put on it is 38T. If the BCD is 74mm like on a triple crank, the smallest chainring that will fit is 24T. You didn't mention if you have a double or triple Shimano 105 crank, or which BCD it has. If you have a double, you could possibly switch it with a 105 triple and only use the inner 2 rings, but your chainline will be about 2.5mm further inward. TA and Stronglight sell 24T chainrings for 74 BCD, and I think they also have 33T for 110 BCD and 38T for 130BCD. Spa-Cycles in the UK also sells cheap chainrings. (for symmetric 5 arm bolts.) If you have a fancy asymmetric 4 arm bolt then you have to look to more expensive chainring manufacturers like mentioned above.

Shimano also sells GRX crank with 46/30T, with asymmetric 4 bolt 110/80BCD, and technically you should be able to fit 26T on 80BCD but nobody makes them for Shimano. The GRX will move the chainline 2.5mm further outward.

If you want to go the more expensive route, Sugino makes the OX cranks which are 110/74BCD double with the standard road chainline, with 145-148mm q-factor, and as short as 160mm crank arm length.

tomgdaly

Thanks - very comrehensive. It's a double chainring - 110 BCD I guess. The GRX looks like the best option.

smashndash

Just make sure to get the GRX FD as well. 2.5mm is lightyears.

Canker

tomtomtom is wrong. Dsaul posted before him showing a 48/32 option for your 105 crankset but they also make a 46/30, I'm running the 46/30 on my 105 crankset myself. Now cost wise the GRX setup might be the better option. Those absolute black chainrings are not cheap. GRX wasn't around when I bought my setup.
https://absoluteblack.cc/oval-road-c...-for-110-4bcd/

tomtomtom123

Well, 33T on 130BCD is the minimum if you're counting a circular chainring. The 48/32 is an oval setup with a special chainring bolt design that will only work with these 2 specific rings and nothing else due to the way it lets you get away with going under the circular diameter of the 5 bolt pattern (or 4 bolt pattern). There was no text showing the number of teeth for the link, which can show up truncated on mobile display. Yes, the 32t oval will be lower geared than the 33T circular, but it costs more than a brand new GRX 46/30 which can be found around here for $70.
The 46/30 oval is for 4 bolt pattern. The OP didn't say if he has 110BCD in 4 or 5 bolt pattern.