Replacing drive set.

stewart_asbury66

Hi again,
So my specialized rock hopper 2021 has a 30 tooth chain ring the stout peddle set iv heard it may help me to swap up to a 32 tooth chain ring but my chain ring is a connected item to the drive pedal so i,m looking into possibly upgrading the bottom bracket and getting a peddle set that i can add a 32 tooth chain ring onto so i can bolt it on rather than as is now its fitted to the peddle does anyone know what i,m looking into as in what bottom bearing and a decent but not over the top peddle set reason for this is its also going to be used for commuting to work as well so I feel I would gain by having the 32 tooth chain ring on it gear and speed wise when its being used on the road ???

JBA

That would be so much easier to read if you added some punctuation!

I believe the Stout chain set has a direct mount chain ring so you should be able to change it for a larger one.
If you remove the chain set (self-extracting bolt - look it up) you should see that the chain ring is held on by a screw-in collar similar to a cassette lock ring.
I don't know what the availability of replacement chain rings is though. Stout is Specialized's house brand so you'll have to do a bit of research to find out what make of chain rings can be fitted.

stewart_asbury66

Hi thanks for the reply but as feared the chain ring on this bike is fixed to the drive pedal no way of removal

Ncovidius

stewart_asbury66 said:

Hi thanks for the reply but as feared the chain ring on this bike is fixed to the drive pedal no way of removal

That looks a lot like a removable collar in the shot ( although admittedly I’m not familiar with those chainsets ) It looks like it will come off with a standard threaded BB cup / centre lock brake rotor removal tool. I’m happy to be corrected if I’m wrong though.

reaperactual

Looks suspiciously like a 3 piece square taper crankset, looking at the hole obviously.

Does the non drive side crank come off with a centre crank bolt the same way?

It does still look like the chainring is direct mount and replaceable but as mentioned it's a unique/unusual Specialized crankset.

On the other hand you can see it properly so you could be right and that specific chainring isn't replaceable. 🤔

stewart_asbury66

yes both come off with a centre bolt and crank puller tool and its deffo not removable ive even found a thread where another guy was asking the same thing and he contacted specialized and they confirmed it is non removable.
The thread also stated that a Shimano XT BB-MT800 - HollowTech II Bottom Bracket - Threaded 68/73mm may be a upgrade to a bb for this frame and then I may have more options for a different crankset meaning I could also then fit a removable chain ring hopefully thoughts please ???

reaperactual

Seems like you have a standard BSA/ English threaded 68 or 73mm wide bottom bracket shell, (likely a 73mm).

Any BSA threaded bb will be fine and works for both shell widths depending on bb spacer configuration.

If you decide on Shimano Hollowtech II specifically then there a couple of bb's to choose from.

https://bike.shimano.com/en-EU/product/component/deore-m610/SM-BB52.html

Quite a few Shimano HT2 1x mtb cranksets available and also a few copy brands that use the same Hollowtech system. Either with replaceable direct mount or spider mounted chainrings in various sizes to choose from.

You can go with a bigger chainring and only limited by clearance from the chainring teeth and chainstay.

mully79

Note changing from a 30T to a 32T chainring will gain you approximately 1mph if you're using the smallest rear sprocket which is about 20mph on a 650b at 90 cadence.

If you're fit enough to average 20mph on a rockhopper commuting then i'd be impressed.

stewart_asbury66

In general on my other 2 bikes I use a 32 tooth front chain ring so i,m used to what power I can put to it in a situation i,m just fnding i,m struggling with this 30 tooth chain ring especially on long rides can really tell that im peddling a whole lot more.

stewart_asbury66

Hi ive found a frew possibilities now but thing im not sure about is they state chainline sizes and ive no idea what mine is ???

mully79

In the case of a single ring its the distance between the centre of the frame (seat tube) and the teeth of the chainring.

stewart_asbury66

So do I measure from centre of seat tube to inner or outer of chain ???

mully79

centre of seat tube to middle of chain ie the teeth of the chain ring

stewart_asbury66

So crank set I was hoping to get the shimano DEORE M5100-1are impossible to get in this country atm im assuming due to covid. Ive now seen the RACE FACE AEFFECT 24MM MTB CRANK ARMS - BLACK which is the correct spindle width for the bb I mentioned earlier but it says spindle length is 137mm now ive no idea what length the spindle needs to be for my bike once i fit the new bb any ideas please ???

stewart_asbury66

All done now really straight forward and a nice low price upgrade that I can deffo feel the benefit of.

stewart_asbury66

One last question im going to buy a 34 tooth as well now im assuming if i put the 34 tooth on im at the point then where I would need to have another chain with more links in it ???

reaperactual

If you are still using the original chain that you used on the original 30t chainring then it would be a good idea to fit and size a new chain.

Worth buying not just for getting the length right but also to avoid any wear on the new chainring if the chain is well used and stretched a little.

Be careful with choosing a new 34t if you buy a non Shimano brand. Your new cranks and many Shimano cranksets have an assymetric bolt pattern and need a matching bolt pattern on any replacement chainring.