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At a social distance of several hundred miles I am trying to help my father upgrade the gears on his 2016 Specialized Stumpjumper.
It has 2x10 at the minute and we are planning to put 1x11 (or probably not 1x12, see below) on it.
At present it is a mix of SRAM X5 stuff that is four years old, although it is still in decent condition he rides a fair bit, the front mech is tricky for him to set up and he never really got on with the rather clunky shifting. But he would prefer to do the upgrade on a reasonable budget so using the existing double crankset (SRAM S-1250 double with 104/64mm BCD into a PF30 BB with chainlines of 46/52mm against ideal non-boost of 49-50mm) and rear wheel (with non-boost Specialized hub and standard HG freehub).
The current gearing is 36/22T on the front and 11-36T on the cassette. I am not a particular expert but Sheldon’s gear calculator says that is a gain ratio range of 1.2-6.4
Now I think I am correct in saying that to go 1x12 with either stock Shimano or SRAM means a 10T smallest cassette tooth and different freehub so on that basis those are out but I think I could get a Sunrace MZ90 option with 11T smallest that would fit but not really all that fussed on being 12spd and that cassette is pretty pricy. So that means 11spd it is.
It looks as though 11spd XT or NX are about the same price (NX maybe a little cheaper) and chainring, chain, shifter, rear mech and cassette can be had for around £200.
Not exactly sure which to go for and have a few questions on part picking for each that I am hoping people can help with:
SRAM NX option resulting in gain ratio range of 1.4-5.3:
Shifter: NX 11spd, band clamp
Cassette: NX 11spd, 11-42T
Rear mech: NX 11spd
Chain: SRAM PC-1170
Chainring: One-Up, 30T - Question – this says it comes with inbuilt offset so I am guessing that is all that is needed if mounted in current outer ring position?
Shimano XT option resulting in gain ratio of 1.3-5.3:
Shifter: XT 11spd, I-spec B mounting
Cassette: XT 11spd, 11-46T – Question – Does the big range work OK?
Rear mech: XT 11spd, Mid-length cage – Question – Is mid length the right length: I am guessing the longer one is for 2x11 setups?
Chain: SRAM PC-1170 (I prefer SRAM chains!)
Chainring: One-Up, 30T
So help on the questions appreciated to make sure the parts ordered will fit. I think I am leaning towards XT as it has a slightly larger range (and also biased view as that is what is on my bike) but any opinions or corrections to the shopping list welcomed.
Oh and here is the crankset, what do you reckon are the chances of getting the chainring off and a new one on without taking the crank off BB? And if the crank has to come off is that difficult? Guessing from the self-extracting bolt this is a three-piece affair.
You can go SRAM 12sp if you like - SX/NX Eagle is 11-50T and fits on a standard Shimano freehub. Plus it's all steel, so it'll last.
Apparently the Shimano 12sp stuff is very good, so maybe XT/SLX 12sp shifter/mech, SRAM chain and cassette, and then whatever chain ring you fancy (I use steel NW for durability as it's only a minimal weight penalty).
dogbrian beat me to it, I was looking for the reason you couldn't go 12 speed SRAM using the shimano hub?
You could "probably" * get the chainrings on and off the crankset without taking it off the BB, but it would be a 10 min job for both if you can get it off as opposed to an all dayer with it in place
*Ask an Adult.
And if the crank has to come off is that difficult?
If it's been fitted to the correct torque, and never removed, then it could be interesting. You'll possibly need a long bar to fit over your allen tool, and someone to help hold down the bike while you apply a terrifying amount of force to it. 🙂
Also, if you go 11-50T cassette then you can resize the chainring to keep parity with the lower or higher gears without losing as much from the other end. https://www.bikecalc.com/gear_ratios
I picked up the same bike few years back as my first bike, the shop converted it to 1 x by swapping the rear cassette for the sunrace 11-40 10 speed cassette and the front chainrings to a 30tooth chainring. Mech, chain and shifter didnt change.
The bailout geat wasnt the easiest at 30-40 but worked fine for me for nearly a year before I got a new bike.
I'd probably stick with 11sp and an 11-46 cassette, as you suggest OP.
Definitely XT shifter, then either SLX or XT for the rest. And possibly a Sunrace cassette if he would prefer the cog ratios it offer.
You might get the chainring changed with the cranks in situ, but you might not. Will the BB not need attention after four years of regular riding anyway?
Thanks all, I had not spotted that NX was available with 11T. The SRAM 12spd stuff is barely any more expensive either but availability looks very limited at present, lots of places out of stock though Tweeks (never used them) look to have it all. There are some really good <£250 prices on complete 12spd NX groupset but can't find one actually in stock so it is a bit academic!
@oikeith that sounds like a good budget option but with four years wear on the parts and since he doesn't love the shifting action fairly keen to swap the shifter anyway. He is in his 70's too so wary of loosing lower gears as whilst he is very fit the power is probably less than someone younger.
@cha****ng Good idea to mix in SLX parts and save a bit. But agree I really like the XT shifter and iSpec B ones are a bargain! Swapping the chainring is mainly a logistics issue if he cannot get the crank off. He has a hardtail for grotty weather so this one is the summer bike and most of the time ridden in the Hertfordshire desert but I have not given it a waggle myself so may be worn!
Make the effort for the 12 speed. 11 speed offers little of the benefits and also gives you a reduced range compared by 2x - important if he's in his 70s.
Lots of the NX 12spd complete groupsets don't mention if they are for boost or standard, how do I know or are they somehow suitable for either? Guess this is mainly about the crankset.
Also guessing I would need an adaptor to change matchmaker clamp to bar clamp as the brakes on his bike are Shimano
SRAM achieves boost spacing on its cranks by offsetting the chainring so no big deal there.
It more about the discrepancy between chainring offset and rear hub offset which can make chain line really poor on 1x.
I guess you'll have to contact some of these retailers for more details?
Ah sorry I should have been clearer, his bike is not boost spaced so I want old standard spacing and chainline.
Which will be easy. Just get the non-boost crank, which is only made boost or non boost by the chain ring.
You just don't want to buy the one with a boost chainring and then buy another non boost chainring ontop.
Can I be honest, if this was my Dad (69 year old retired teacher) and the bike was currently functional, I'd get him to take photos of everything for reference, I would then go do the parts hunting, order all the necessary items (to my address), and then leave the whole operation until I can do it in person post lock down...
Doing it remotely just ain't going to work, I bet He's not got all the tools necessary has he?
If it didn't require a change of the crankset I would be confident he could fit the rest of the stuff (he is pretty handy, has sufficient tools and an interest in such things).
So deciding to change (or needing to remove) the crankset is the big deal, it may need a long bar as it has never been off. And then a change in crankset to NX Dub would need a new pressfit BB that I don't have tools or knowledge of so probably a trip to a shop for that. The compromise would be to swap the chain ring to a OneUp one for now and swap the crankset and BB later.
But yes it would be ideal if I could do it in person (in which case he could also visit his two month old first grandson he has yet to meet!)
If your dad isn’t up on bike tools and work then this sounds like a recipe for disaster. Given you’ve mentioned he’s not good at adjusting a front mech then this doesn’t bode well! With that, as long as the low and high screws are set correctly then it’s just a case of cable tension pretty much (as long as the mech is angled / rotated correctly).
If you decide to go with it I’d try to make it as simple as possible - so that means keeping the current freewheel standard firstly. So that rules out shimano microspline (so their 12 speed) and Sram XD (their GX and upward 12 speed cassettes).
Biggest range therefore is probably 11-50 cassette wise - Sram SX / NX 12 speed cover those (but are really quite heavy). I’d imagine Sunrace do an 11-50 in 12 speed - if so worth comparing the cost / weight difference. If going with either of these options I’d go with a Sram shifter and mech. If you can get to a gx mech and shifter they’re more durable - but if lower try to get the gx mech and NX shifter combo. I’ve not heard good things about sx.
If you want to stay 11 speed I’d be inclined to get a Sunrace 11-46 cassette (not sure if 11 speed shimano does 11-50 or if Sunrace do 11 speed 11-50) but then go with shimano shifting. SLX mech and shifter will be more than fine for your dad and will be an improvement on X5.
Either way, be careful on brake mounts. If your dad has shimano brakes and Sram shifters then presumably he has a band on brake rather than it working with his Sram shifter via matchmaker. If this is the case then try to get shimano band on shifters for ease.
The cranks could be an issue on chainline and getting a small enough chairing. Just check if Sram make a 30t chainring in non-boost that fits the 104pcd. I think they do but just check.