jgwilliams

I read the other day that the lower end SRAM Eagle 12-speed cassettes fit on a standard HG hub, which set me to thinking about upgrading my wife's mountain bike. But then I read elsewhere that the SRAM Eagle SX groupset won't fit because it was designed for Boost spacing, and her bike is an older one with QR hubs. The thing is, though, comparing my bike (which is Boost) to hers, I can't see why it matters. Sure, I couldn't fit a boost wheel on there, but the positioning of the derailleur relative to the hub looks pretty much identical on both. I have to admit up front that it was more or less idle speculation; there's so much that would need to be upgraded I'm not sure it's worth it, but can anyone explain why it wouldn't work?

Joe Remi

A cursory reading of what Boost spacing means for that group is the cranks are designed for those frames/chainline. I don't see any reason the shifter, derailleur and cassette wouldn't fit in a normal 135-spaced frame as long as the freehub will accept the cassette.

Which brings me to a question someone else here can hopefully answer: Do these 12-speed cassettes fit on 8/9/10 and 11-speed MTB freehubs? I ask because I have a SunRace 11-speed 11-50 on my bike which will fit 8/9/10 without a spacer, and uses a spacer on my 11-speed White Industries hub.

jimc101

What do you have at present, and what do you expect to get from 'upgrading'?

If your looking at going 12 speed, that normally would mean new shifter, RD, crank/chainring (you have to go 1x for this) and cassette, you can get this all in one for £230 from CRCWiggle (SRAM NX), is it worth it, you need to make that decision.

For hub fits, unless you have a really old 7 speed only Shimano HG (think upto 1993ish) all Shimano HG MTB freehubs are the same spec upto today (road and Microspline being a different matter) Plenty of on-line guides like this one Which freehub body do I need? SRAM and Shimano 9, 10, 11 and 12-speed MTB setups explained | off-road.cc

tcs

Shimano XT Q/R hub 135mm OLD. SRAM Eagle NX 12-speed.



HTH

Iride01 

You sort of put out a hypothetical question that you can only get maybe answers for.

It would help if you tell us what is the motivation to change. More in between gears? Lower or higher gear ratio? As well what you already have will determine whether you can replace one thing or have to replace everything.

jgwilliams

Yes, you're right - my apologies. As I mentioned, it was idle speculation as I'm not sure the bike is worth spending much money on. It's a Giant XTC 4 which I believe dates from about 2008. I bought it used as a cheap way to get into mountain biking to see if it was for me. It's a medium frame which is really a bit small for me, but it's done me quite well. It has Shimano Deore 3 x 9 gears, which work ok but I do get chain suck from time to time moving from the smallest to the middle chain ring.

Last year I bought myself a Sonder Dial with Shimano XT 1 x 12 gears. I kept the old bike for my wife to see if she might also get into mountain biking. Having now ridden a nice bike I can see just how much things have improved over the last 15 or so years. Hence my wondering about whether to upgrade the Giant. I think the two biggest areas of improvement for me personally are the change to 1 x 12 gears and the much better front forks. Hence my idle speculation when I realised that an Eagle SX cassette might fit on the Shimano HG hub.

On the one hand, I quite like messing around with bikes and it would be quite satisfying to upgrade the gears. If I'm honest, though, that change alone would probably cost more than the bike is worth and it would still leave me with a bike with forks that are on their last legs (Manitou Spice - so not that great even when they were new) and bearings that have seen better days, etc. If the bike was lower mileage with halfway decent forks I might go ahead. What do all you good folks think?

Canker

You might want to look at Microshift Advent X instead. Yeah it is only 10 speed but it still has a lot of range 11-48, it is lighter, and it is cheap. If you google around you can find the whole kit for $160 including the chain. If the crankset has replacable chainrings you can just take them all off and replace the middle one with a narrow wide ring and your done.

Joe Remi

Does your wife like the bike as is? If so you have your answer.

jgwilliams

I think she's ok with it. I suspect that if she were to try a more modern bike she might like it more.

jgwilliams

I was doing some more reading around and found the answer. There are two versions of the chainset with different offsets depending on whether you have boost spacing or not. It looks like the difference is only 3mm, so I'm not sure that the performance would be that awful if you had the wrong one.

Keefusb

My wife tends to feel guilty when I upgrade her bike, so she is more likely to ride it if I spend some money on it.

jgwilliams

Lol! My wife has been spending more time riding horses lately and feeling guilty about the money she's spending on that. Doesn't seem to stop her though. Horses are odd, though: the pedals don't go round and the handlebars and brakes only work in an advisory capacity. On the plus side, punctures are rare.