Specialised Sirrus X Chainring change

[Sharky]

With what we have all learned about your set up, what is the real issue?
Is it redundant low gears that you never use or feel that you run out of revs when already on the 11t?
Changing to a 50t is going to be costly. New chainset, chain and tools to do the work.

Switching to a more compact 11-34 cassette may provide the higher gears at the low end that you are missing.

Good luck

 

[Orfeus67]

I'm not worried about redundant gears - they're always there for when an unexpected journey throws up a serious hill - I just want to get a bit more speed than the 40/11 combination will give me on the flat. But given the cost it may be the upgrade isn't worth it and I should either accept what I have or be more savvy with my next purchase.
I'm a recent returner to cycling and purchased the Sirrus X 2.0 on the basis that I had a Specialised Hardrock 20 years ago (that was nicked) which I really loved, and wanted to re-engage with the brand. Romantic rather than pragmatic.
I really appreciate all the tips I have been given, especially as a first-time-poster.

 

[Orfeus67]

... as well as a bit more speed, also I want to have to work a little harder (when on the flat). The 'X' is supposed to stand for 'exercise', and I'd like the gearing to push me more...

 

[iluvmybike]

... as well as a bit more speed, also I want to have to work a little harder (when on the flat). The 'X' is supposed to stand for 'exercise', and I'd like the gearing to push me more...

The 'X' stands for Cross bike - intended use is for gravel, easier off-road routes and light bike-packing which is why it has a single 40t front ring. (and wider tyres, pannier mounts etc etc). If you want to go faster then a road bike would suit you better as it would have better gearing for that use

 

[Ajax Bay]

The OP has a 11-42 cassette (see my early post) so no (practical/economic) option to have smaller smallest sprocket.
Has no chainring bolts/BCD, so larger ring needs new square taper (assumed) chainset and N-W ring (as others have said). These may be self-extracting bolts on the cranks, but I can't tell (so crank extractor tool may not be needed). Worth noting the spindle length of the bottom bracket and note the length required of any replacement cranks.
Longest gear currently 98 inches so would spin out on gentle downhills: price you pay for choosing a 1X.
But at perfectly comfortable 100rpm cadence you'd be getting 29mph/47kph on the current set-up.
http://www.gear-calculator.com/?GR=...7,33,42&UF=2170&TF=100&SL=2.6&UN=KMH&DV=teeth
Finally, as @Cycleops has highlighted, well worth a careful check of chainring / chainstay clearance. A 50t (on the same chainline) will be 25% greater radius (104mm). So measure the current distance between the 40t chainring (83mm) and the chainstay and work out where on the chainstay a 50t would come to, and how much 'wider' the chainstay 'moves in those 2cm.
Fwiw, if you do pursue this, and will still wish to climb steep hills, then a jump from 40t to 50t is pretty radical. At least consider a ring size in the 40s (eg 44t).

 

[Orfeus67]

really helpful, many thanks AB.
According to the Specialised marketing, the X model is the Fitness range. I guess it comes down to where the designers specify the gearing, and on a 1x8 there's limited scope, so I assume they see 40+11/42 as an ideal 'all round' solution. Food for thought.