Hello
Building a tallboy next week. I've built a few road bikes but no MTB. I've got a few questions:
1. Will the GX groupset come with cable inner/outers like the road groupsets do?
2. Will the SRAM brakes come with brake lines?
3. I've seen post mount adapter things online I don't understand what these are for and do I need them? Running new level TL brakes on 18 pike rct3 with 180/160 rotors.
4. BB is 73 English thread. Are SRAM spindles 68mm like Shimano? I want to run the cheaper Shimano BB.
5. Will I get away with a normal track pump for sealing tires? Probably going to run 25 or 30mm internal rim with 2.25 & 2.3 tires.
6. Can I use my bike specific cable cutters for brake lines or do I need a specific tool?
Lastly, anyone want a build thread with pics? Can also take the bike to the woods with my DSLR and flashes and get some arty farty completed shots.
Thanks in advance.
Daimo
Timelapse and photos are always interesting
1 & 2 Don't know about SRAM kit
3. The adaptors are to move the caliper to the correct position for the size of rotor you are using. Not sure about Pikes but Rebas come with post mount for 160mm rotors so if you want to fit 180mm or 200mm rotors then you need the appropriate adaptor. Some forks have IS mounts so you'd need an IS to PM adaptor in that instance.
4. Dunno
5. Possible but I doubt it. Depends on the tyres and the rims, some combos are easy some aren't
6. For normal lines they should be fine, don't know about braided.
4. BB is 73 English thread. Are SRAM spindles 68mm like Shimano? I want to run the cheaper Shimano BB.
The spindle and locking method is different so you can't mix.
Hope threaded with gxp adapter is probably the best upgrade there.
Last gx I had came with inner, outer can't remember.
Brakes will be complete but will probably need trimming and bled for internal route - great job for a shop there.
1. Yes, should come with shifters.
2. Yes, should come complete and bled. May or may not come with so are olives and barbs for hose shortening.
3. Depends on what rotor size you want to use. MY18 Pike is direct mount for 180mm rotor. Best guess for the rear is that it will be 160mm direct fit. If you want any other size, you'll need adaptors.
4. No. SRAM 24mm axle is GXP which has a stepped shoulder on the non drive side. After market bottom brackets are available, but I don't think they're cheaper.
5. Depends. Some tyres/rim combos will work.
6. A clean straight cut is all you need, doesn't matter how you achieve it. Should be okay.
The shifter will come with an inner cable only. The brakes will come with brake lines. You will need a post mount adapter if you want a rotor bigger than 160mm.. Shimano BB is not compatible with Sram cranks as Sram are taped. Cable cutters will be ideal for brake lines and if you do it properly then yes a track pump will work.
1&2 yes
4, your issue won't be 73/68mm, it will be whether the BB/Crank is (sram) GXP or not, what are you using for both?
You may also require a caliper mount for the rear depending on wether your frame is post mount or IS
Awesome, literally everything answered, thanks .
180mm rotors up front and someone mentioned the 18 pike is 180 direct mount so ✓✓✓.
Will just buy the more expensive GXP BB over Shimano as can't be doing with the hassle of adapters.
Looking at the tallboy page, they're factory built 180/180 so will I need adapter at rear for 160 rotor?
Building a tallboy next week. I’ve built a few road bikes but no MTB. I’ve got a few questions:
1. Will the GX groupset come with cable inner/outers like the road groupsets do?
Probably..
2. Will the SRAM brakes come with brake lines?
Yes they should
3. I’ve seen post mount adapter things online I don’t understand what these are for and do I need them? Running new level TL brakes on 18 pike rct3 with 180/160 rotors.
Your post mounts will probably be for 160 rotor by default so you'll need an adapter for rotors larger than that
4. BB is 73 English thread. Are SRAM spindles 68mm like Shimano? I want to run the cheaper Shimano BB.
No you need a SRAM GXP bottom bracket, they work differently
5. Will I get away with a normal track pump for sealing tires? Probably going to run 25 or 30mm internal rim with 2.25 & 2.3 tires.
maybe but you might hate your life if it doesnt work. Tubeless inflator is worth having.
6. Can I use my bike specific cable cutters for brake lines or do I need a specific tool?
Use a stanley knife and make sure you get a nice square cut - hose cutters aren't expensive though.
Lastly, anyone want a build thread with pics? Can also take the bike to the woods with my DSLR and flashes and get some arty farty completed shots.
Yes - am about to do this myself and it's cool to see.
EDIT - OK, everyone else already answered 🙂
On the crank thing some people have already covered off if it’s gxp then it’s not Shimano compatible so you’d need a gxp B.B. or an aftermarket compatible one. Unless it’s the new Sram ‘dub’ standard in which case you need a dub B.B.
Pretty sure it wasn't dub as I remember that being a more expensive option on the website .
Regarding SRAM GXP, they're shite! They make the RaceFace cheese bearings look solid. Actually no, at least shite is useful as you can use it as fertiliser.
@mikedabear presumably meant to say that the SRAM spindle is tapered not taped 🙂
Regarding SRAM GXP, they’re shite! They make the RaceFace cheese bearings look solid. Actually no, at least shite is useful as you can use it as fertiliser.
Ok, so what are my options if I want to keep it under £30?
1 - It'll certainly come with inners. It may come with outers - certainly Shimano ones do, it'd be tight of Sram not to.
2- Yes, they'll be either all ready to go (although the hoses may be too long, but I'd not worry about that) or the hose will be attached to the caliper and there will be a little cover on the end of the hose and the hole in the lever where the hose goes. You trim the hose to whatever length you want, fit the screw fitting for the lever onto the hose first, then the olive (little brass ring) second then the barb (little brass tube thing with ridges to go inside the hose) (which will be in a little bag) then screw that into the lever.
3- For your set up with 2018 Pikes you do not need any adaptors. New Pikes are set up for 180mm rotors. For 160mm on the back you won't need anything either.
4- Mountain bike spindles are 73mm, you use spacers on the BB to make up for the difference in width (where to put the spacers is in the instructions). You must use a Sram GXP BB with Sram cranks, or a Shimano BB with an adaptor (which is more faff and will cost just as much).
5- This is impossible to say - probably, but you'd need someone with the same tyre and rim combo to confirm.
6- Yes, or a Stanley knife.
5. Maybe...I have done a fair few tubeless set ups and haven't been beaten yet just using a track pump.
6. I don't like cable cutters for hydro lines, I find they deform the ends a bit and it's hard to get a perfectly square cut. Either use a stupidly sharp blade (I used to use the leatherman blade that i got sharpened by a knife maker in the Alps) or even better one of these:
1 – It’ll certainly come with inners. It may come with outers – certainly Shimano ones do, it’d be tight of Sram not to.
If it's a proper, retail GX groupset then it definitely does not include outers. Buy a box of the stuff for the garage as it's incredibly useful to have around anyway.
Looking at the tallboy page, they’re factory built 180/180 so will I need adapter at rear for 160 rotor?
They may put the adapter on to fit a 180 rear. If its 180 without an adapter, i don't think you'll be able to fit a 160
GXP aren't great but you can service the bearings to extend their life so the best thing to do is open them up when new and pack them with more grease.
To do so: there is circlip with a little notch in around the inside of the outer shell, use a screwdriver in the notch to prise it out of the slot it sits in by pushing the end of the circlip towards the centre of the bearing.
Take the bearing seals off (also carefully) and you'll see the bearings in a plastic race - add grease, replace seal, replace circlip. Job done. Repeat occasionally.
Ok, so what are my options if I want to keep it under £30?
Hope, I don't really remember doing much to them at all over the life, the 3 I had all moved on with the bikes. It's much better value in the long run
Going to open a can of worms here but considering I've made a poor choice for the BB, maybe I should have come here before choosing my groupset.
I definitely dont need the range/granny gears on the gx eagle cassette but I chose it because it comes with the 52mm chainline I need for my boost frame. I also like the direct shifting on SRAM like someone's taking a sledgehammer to the back of your head so hope this is the same for their MTB groupsets.
Any alternatives? I got the groupo for £317 and I could only find the Shimano XT M800 in non boost. I'd have had to buy the boost crank arms separately and then the Shimano groupo is the same price as the SRAM with one less year and less range.
a poor choice for the BB
Just use a Hope BB. I actually quite like the last 2 sets of GXP cranks I've had, having always liked Shimano. Liked them so much when a deal came up for some Carbon Stylo GXP cranks I snapped them up and stuck a Hope BB with the GXP adapter and haven't though about them for the last 6 months.
GX Eagle is far better than anything Shimano makes atm, new XTR not withstanding, so just stick a Hope BB in their with the GXP cranks and don't worry about it.
Just doing a build for my mate and the gx eagle shifter did not come with any outer. Unbelievably tight from Sram!!
I’m still on the same gxp B.B. my bike came with last May / June sort of time. I haven’t done any maintenance and when you take the chain off he cranks they still spin smoothly and there isn’t any play I can feel in them. The previous bike that had gxp for a B.B. was gritty and grindy after the same period of time so maybe it’s luck of the draw - or maybe over time Sram have improved the design / bearings.
I’m not the highest volume rider in terms of use - I tend to get out once a week on my bike but in all weathers so it does get wet and muddy.
When it eventually does die I’ll be weighing up a straight replacement like for like vs the extra cost of a hope B.B. with gxp adaptor.
off topic, but if anyone at a bike manufacturer asks if they can design a new standard in MTB, they should be shown this thread as exhibit A for the '**** no' camp.
Just doing a build for my mate and the gx eagle shifter did not come with any outer. Unbelievably tight from Sram!!
Was it a proper retail box set or bits in bags? Normally I'd prefer to pick some good quality outer to use and with most frames being internal the amount needed is a lot less these days.
It was a proper retail boxed shifter
Was it a proper retail box set or bits in bags? Normally I’d prefer to pick some good quality outer to use and with most frames being internal the amount needed is a lot less these days.
I have a GX full retail groupset on my desk (in the big, shiny red box!) and it 100% does not include outer cable.
Was mostly checking as I couldn't remember I think my mate lobbed some cable outers in for me as there was a cock up getting it from SRAM and it was chasing me across Oz before heading to the US 🙂
Can't believe SRAM are that right. My SRAM Red groupset came with outers but that's their highest road groupo .