1991 stumpjumper with 1x12 NX Eagle?

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1991 stumpjumper with 1x12 NX Eagle?
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flag allsystemsghost
Posted: Feb 23, 2021 at 13:47 Quote
photo
can I fit this 12 speed cassette on stock 7 speed wheel/hub? or will I need to build up a new wheel/hub set up? trying to do the on the cheap(ish) https://www.sram.com/en/sram/models/gs-nx-1-a1
flag PACNW-MTB
O+
Posted: Feb 23, 2021 at 14:04 Quote
I think your frame needs boost spacing to accommodate a 12 speed cassette.
flag PoeticThreeD
O+
Posted: Feb 23, 2021 at 14:19 Quote
Unfortunately the answer is no. The hub on your bike has an old shimano 7-speed freewheel body on it which isn't going to be compatible with the Sram XD driver that the NX cassette uses. I also believe that your frame would need back wheel spacing (boost spacing) to accept a new hub that, so you're not going to be able to buy a new wheel and have it work on this frame.

If you're after 12 speed shifting with a large gear ratio, I'd recommend something like the following:

-Sunrace MZ 12-speed cassette (these fit on old hyperglide hubs, no new hub needed)
https://www.sunrace.com/en/products/detail/csmz800

-Shimano M6100 12-speed rear derailleur and shifter (a great budget option, with superior shifting to NX)
https://bike.shimano.com/en-EU/product/component/deore-m6100/RD-M6100-SGS.html

You'll also have to make sure that you have the 'right kind' of 7 speed cassette so that you can switch to a higher gear cassette, this vid is a good guide: https://www.youtube.com/watch?v=n5YkkAP_QVI

If budget is a big concern, you should also look into just going to 10-speed or 11-speed; either would provide a huge leap in capability and you wouldn't be losing much compared to 12 speed (I ride enduro-type stuff and still used 10-speed on my endure bike)
flag allsystemsghost
Posted: Feb 23, 2021 at 15:30 Quote
wow! this is the most useful and thoughtful reply to any post on any forum i’ve posted on! thanks for the info, i’m going to chase the sunrace/shimano combo. the research continues...
flag andrew95
Posted: Feb 23, 2021 at 17:07 Quote
Fantastic info from the above poster.

I was in a similar situation when I converted a 1992 trek 7000 into a budget gravel bike with drop bars and gravel kings.

I ended up going for the micro shift advent x stuff as it was an extremely cheap option to have both a road shifter and a clutched mtb style derailleur. If you don't already have an eagle drive train sitting in a parts bin I'd highly recommend the advent x line. Super affordable and really impressive range out of a 10sp (11-48T).

One thing I ran into is that my 7sp HG hub was only 30mm wide, any hubs that fit 8+ speeds need to be 35mm. I grabbed a wheel tech (Rockys house brand) hub off eBay for 20 bucks shipped and stole the free hub off that hub and put it on my wheel. Super easy with some cone wrenches, a big ol Allen key (10mm for mine) and some fresh grease.

Another note for some useful/interesting sources. r/xbiking is a reddit community of weirdos doing fun things with old frames. Theres actually quite a few stumpy builds on there that you could probably copy drivetrain wise. Also "spindatt" on YouTube is a good Canadian kid that also does random budget builds. https://www.youtube.com/watch?v=YPymQz4j_HM

I'd love to see a follow up post of what you decide on running as well.
flag allsystemsghost
Posted: Feb 23, 2021 at 23:14 Quote
amazing. more good info as well. I don't have parts yet, and the more research I do , the more i'm glad I didn't impulse buy a groupset...

hot tip on the cheap hub to pull the longer free hub! I haven't pulled my cassette so I don't know yet if I have the 30mm or 35mm, but good to know there's an easy workaround.

I love that reddit thread - it looks like I found my people Smile

all of this guy's builds are fantastic too. I spent a lot of time tonight watching a bunch of these. it's like ASMR bike builds, very soothing. https://youtu.be/dbLxSsfKzmA

when I make my choices, i'll try to keep you updated
flag PoeticThreeD
O+
Posted: Feb 24, 2021 at 7:17 Quote
Looking forward to see how this shapes up Smile didn't know about that microshift either...maybe something for my gravel bike.

Good luck dude!
flag ScaryGuiTarS
Posted: Feb 24, 2021 at 8:21 Quote
It's really remarkable seeing such a vintage design of the stumpy. There are so many older bikes that just don't interest riders of the modern designs, but this here is an example of an older triangle frame that's still relevant and still holds up as a quality bike. I like that you're putting effort and care into keeping it functioning and still enjoying it.

I'm older and I've actually ridden on bikes through the development of marrying the bmx to the road bike giving birth to the mountain bike. They're SO different now, that I almost forget how much riding I did on a rigid steel frame!

SJ's are my fav' mountain bike no question, and that bike you have there is symbolic of the bike that virtually started it all. I could only image how much fun it is to have that and be able to enjoy it once in a while.

~JSV
flag dirttorpedo
Posted: Mar 1, 2021 at 13:27 Quote
allsystemsghost wrote:
amazing. more good info as well. I don't have parts yet, and the more research I do , the more i'm glad I didn't impulse buy a groupset...

hot tip on the cheap hub to pull the longer free hub! I haven't pulled my cassette so I don't know yet if I have the 30mm or 35mm, but good to know there's an easy workaround.

I love that reddit thread - it looks like I found my people Smile

all of this guy's builds are fantastic too. I spent a lot of time tonight watching a bunch of these. it's like ASMR bike builds, very soothing. https://youtu.be/dbLxSsfKzmA

when I make my choices, i'll try to keep you updated

I would definitely check out the AdventX stuff - lots of positive buzz on it on Spindatt, LockedIn and Path Less Pedaled. You might find it easier to just buy a used rear wheel with an 8,9,10 speed freehub. I tried a free hub upgrade on a 7 speed freehub and found I needed a longer axel to make it work.
flag streetkvnt-kvlt
Posted: Mar 6, 2021 at 22:28 Quote
I'm running Deore 10 speed 11-46 cassette on my 1989 Rockhopper. It's not the original rear wheel (thats long gone to the great wheel graveyard in the sky). It works a treat and I have more ratios than I need day-to-day but it's good to have that extra low 4x4 gear there.
flag PBCpeugeot
Posted: Mar 7, 2021 at 12:00 Quote
while a sram 12 speed cassette will not fit on a 7 speed freehub
it is rather easy to convert a 6 or 7 speed hub to 8,9,10,11,12, type
as the body can be removed with an 8mm allen wrench after removing the axle
(good time to re grease the axle bearings) then you just need a good used 8 speed body
flag ScaryGuiTarS
Posted: Mar 7, 2021 at 14:18 Quote
PBCpeugeot wrote:
while a sram 12 speed cassette will not fit on a 7 speed freehub
it is rather easy to convert a 6 or 7 speed hub to 8,9,10,11,12, type
as the body can be removed with an 8mm allen wrench after removing the axle
(good time to re grease the axle bearings) then you just need a good used 8 speed body
Oh so you're saying for people that want to INCREASE the cassette on their limited wheel, all you need to do is change the HUB to accept a larger cassette.. that it? I think I get it--if I got that right? I didn't really know much about altering the hub for cassettes works.

~JSV
flag andrew95
Posted: Mar 7, 2021 at 19:09 Quote
Yep, in most cases anyways

Coupla cone wrenches, something to catch the ball bearings and hex key and you're on your way to being able to thread a wider more modern free hub onto the stock rear hub.

Heres a video showing how to remove the free hub:
https://youtu.be/SZZdB_P3mmc?t=52

These old mtb bikes are real fun to work on, it starts with just a couple modifications then all of a sudden you have a parts shelf of things waiting to go on.
flag PBCpeugeot
Posted: Mar 8, 2021 at 9:30 Quote
ScaryGuiTarS wrote:
PBCpeugeot wrote:
while a sram 12 speed cassette will not fit on a 7 speed freehub
it is rather easy to convert a 6 or 7 speed hub to 8,9,10,11,12, type
as the body can be removed with an 8mm allen wrench after removing the axle
(good time to re grease the axle bearings) then you just need a good used 8 speed body
Oh so you're saying for people that want to INCREASE the cassette on their limited wheel, all you need to do is change the HUB to accept a larger cassette.. that it? I think I get it--if I got that right? I didn't really know much about altering the hub for cassettes works.

You do not need to change the entire hub
The main hub body spokes and rim remain attached together
It is only the 1/2 of the hub with the ratcheting mechanism that holds the cassette you are replcing
It is easy to do even if you have never taken a hub apart, and learning to regrease the wheel bearings is a good idea anyway
~JSV
flag dirttorpedo
Posted: Mar 11, 2021 at 8:45 Quote
ScaryGuiTarS wrote:
PBCpeugeot wrote:
while a sram 12 speed cassette will not fit on a 7 speed freehub
it is rather easy to convert a 6 or 7 speed hub to 8,9,10,11,12, type
as the body can be removed with an 8mm allen wrench after removing the axle
(good time to re grease the axle bearings) then you just need a good used 8 speed body
Oh so you're saying for people that want to INCREASE the cassette on their limited wheel, all you need to do is change the HUB to accept a larger cassette.. that it? I think I get it--if I got that right? I didn't really know much about altering the hub for cassettes works.

~JSV

So here's the thing. BITD there were two sizes of 7 speed freehubs provided by shimano - a short one and a long one. The long one can accept 8, 9, 10 speed cassets. The short one can't. The long freehub can bolt onto a hub that has a short freehub on it, but because its longer it requires a longer axle. I just did one of these swaps and had to source an longer axle to make it work and its hard to find old school cone and axle kits these days. since you can probably find a used 8 speed wheel for $50 it might be easier and about the same amount of $ to just replace the wheel.

Walmart wants almost $60 before taxes for the part https://www.walmart.ca/en/ip/Shimano-RM33-8-9-10-Speed-Freehub-Body-Unit/PRD244IC0L8CZ49

And then you need the axle. https://www.cyclebasket.com/m9b0s498p0/Components_/Hubs_-_Spares_Axles_Cones_and_Seals_Rear
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