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  • New drivetrain Sunrace50t/Box issues
  • dumbbot
    Member

    Evening,

    New drivetrain shifts like utter shite, assuming all indexing/hanger alignment are correct(they should be i’ve checked and had a shop check). That pretty much leaves chainline doesn’t it? It a Middleburn Non-boost crank with a Hope 32tring and a Boost rear end, I assumed that gave you a better chainline than boost-to-boost and a Boost crankset was only really need for tyre/chainring clearance if desired. I can’t play about with spacers at the BB or the bearing pre-load won’t function, what else can I do ?

    New bike day Swarf content

    Now I’m assuming you have made no setup errors with cable tension, high and low stops, b tension and clutch tension (if adjustable) or compatibility/worn/old component problems, i.e. a draggy worn cable or incorrect length to accommodate suspension travel.

    Is your chain too long or too short?

    If it’s too long/baggy, the shifting will be sloppy (upshifts will be slow downshifts might not happen without overshifting) especially across the smallest sprockets, improving slightly as the slack in the chain is taken up by the bigger sprockets. If too short the opposite i.e. shifting on the biggest sprockets becomes stiff, erratic and prone to dropping down the block under high tension.

    It’s surprising how bad a chain line you can get away with and still achieve good enough shifting! With these high range drivetrains, closer together sprockets, If you have got several things not quite right, it can add up to unridable shifting!

    Premier Icon benpinnick
    Subscriber

    If your set up is still as per the pictures on that other thread then your chain is too short and b tension off I reckon.

    dumbbot
    Member

    OK so things aren’t set quite the same as in the pictures, as both myself and the LBS will have fiddle with indexing/b-tension since and the chain is a full SRAM PC-1130 chain (116links i think) I didn’t remove any links, and it was supplied by the shop that I bought the Box Drivetrain from so knew it was going with a 50t.

    I would’ve assumed that the LBS would’ve picked up on the chain being to short,even if i didn’t.

    greyspoke
    Member

    Which Middleburn spider?  If it is the triple one, then your chainline will be a bit inboard of where more recent double specific non-boost cranksets put it.  According to One-up anyhow.  I tried using an old school Shimano HTII triple crankset and a boost back end and (10 speed) I got graunching on the 9th cog when in 10th, but the shifting was OK.

    I have got my Middleburns to work with that boost back-end now (the other cranks died) by using the Rohloff spider and putting the spacer on the left side.  If you have a 68mm bb you could put all three spacers on the right to get a more outboard chainline?

    But it sounds like the problem may lie elsewhere.

    dumbbot
    Member

    It’s a single spider, 

    The shop that I bought the Box drivetrain from thinks it’s a boost crank/chainline issue ..I dunno.

    Is that 3 spacers I see? 3 is usually for a 68mm shell not 73.

    Premier Icon joebristol
    Subscriber

    Unless there’s something unusual about box mechs is usually use this method to set my gears:

    Start by sizing the chain. Running the chain round the biggest cog at the back plus the front chainring without going through the mech. Do this with the suspension at the point where the chainstay length is at its longest. Add 2 full links on top of the length of the chain.

    Then route the chain through the mech and get it joined up but leave the mech cable undone.

    Using your hand to move the mech set the upper and lower screws so you can smoothly shift through the gears by hand without going off either end of the cassette.

    I then let the mech move into the highest gear (smallest cog) where it naturally goes with no cable attached. Put the cable adjuster on the shifter so it is roughly in the middle of its tension adjustment.

    Pulling the cable tight by hand, check that it moves smoothly / easily through the outer and there’s no roughness or friction.

    Assuming all ok then I pull the cable tight through the rear mech and do the screw up.

    I’d then shift the chain through the gears so the chain is on the biggest cog. Hopefully it gets there without any other adjustment. If it doesn’t quite get there then tighten the cable with the shifter adjuster until it does.

    Then check how far away the upper jockey wheel is from the biggest gear. Most manufacturers will have a stated ideal distance for this – I think around 10mm is how I set my GX 11 speed approximately and it works like a dream. You may need a tiny bit more tweaking of the cable adjuster for fine tuning after adjustment of the b screw.

    You should then be done.

    In terms of chain line just have a look at the chain angle in the lowest and highest gear extremes. On my hardtail that I recently setup the lowest gear sees the biggest chain angle but the chainring is within a couple of mm of the chainstay so I couldn’t run it anymore inboard if I wanted to.

    If anything, running a non-boost crank you would be more in-board than you need to be and the main issue would be chainring clearance of the chain stays.

    If you’re still struggling I’d be wanting Box to look at either the mech or the shifter to check it’s working properly. Have you got a spare Shimano or Sram mech and shifter you could try to eliminate chainline and cable issues?

    dumbbot
    Member

    @ Chester, that’s not how it’s set up on the bike, 1 spacer drive side, I think.(had to play around to make sure the bearing preload nut had space to move).

    Appreciated Joe, but I’m certain it not an indexing issue. I do have the option to pull the SRAM GX 1×11/46tooth sunrace set up off my hardtail(might need a new chain to get the correct length though) That’s a pain, so not ready to do that yet.

    Box have been in touch and asked for some pics in highest/lowest gears so I’ll get that done, see if I’m missing something obvious.

    Premier Icon joebristol
    Subscriber

    I was just thinking you could swap the mech / shifter off the other bike to try with the drivetrain on your bike. If it works then you know it’s you Box mech or shifter that’s the issue.

    Premier Icon benpinnick
    Subscriber

    Chainline shouldnt be an issue, the mid-triple position on your middleburns will be fine, it will be narrow, but narrow is better as a rule.

    whether 116 Links is correct I cant say, what I would say is that if I saw a bike with your mech/chain set up, on any gearing I would expect it to be pretty poor shifting. Remeber too that frame will have a reasonable amount of chain growth too so when you’re sat down that chain will be even tighter. For the gear you’re in that looks just way too short a chain and/or the mech sits a long way off the cassette and the jockeys swung too far forward. Obviously some set ups would work better than others, but they’d all be substandard. You need more chain wrap round the cogs or you’ll potentially be only partially hitting or missing altogether the first shifting ramp that kicks off the shift. Like that I would expect you’d get a lot of half shifts where it sits there trying to shift but never gets there without a bit of additional assistance from the lever.

    Other obvious things, do you have the right speed mech? Sounds stupid but small run manufacturing/import can lead to mix ups with boxes etc.

    PJay
    Member

    I’m a bit out of my depth here (still running 3×9) but I was under the impression that, in an ideal situation, you’d use a boost crankset with a boost rear end (probably wrong though).

    Interestingly the Box website lists both of its 11 speed mech. as having a 46 tooth maximum sprocket size; would this cause issues? The only mech I can see listed with a 50 tooth maximum is listed as 9 speed.

    PJay
    Member

    I’m a bit out of my depth here (still running 3×9) but I was under the impression that, in an ideal situation, you’d use a boost crankset with a boost rear end (probably wrong though).

    Interestingly the Box website lists both of its 11 speed mech. as having a 46 tooth maximum sprocket size; would this cause issues? The only mech I can see listed with a 50 tooth maximum is listed as 9 speed.

    What shifter are you using?

    Premier Icon calv145
    Subscriber

    Put some pictures up of the current set up as it looks miles out in the other pictures.  Somebody else might spot something that you haven’t.

    Premier Icon Yak
    Subscriber

    I don’t know box stuff, but certainly I reckon sram works better when the chain is on the long side of acceptable rather than just lowest gear / shock compressed/ +2. So I tend to go from the other end, ie what’s the longest I can sensibly use in the 10t and with the minimum b tension I can get so I have the maximum chain-wrap.

    Plenty of chains come in 120 links too and given the gear range + your longish chainstays, maybe 116 isn’t enough?

    dumbbot
    Member

    MMm..ok I think you lot is onto something with the chainsize, im just stripping & replacing the whole cables just in case and i’m looking at the angle of the derailleur cage when its sitting idle and its nothing like where the its sitting on my hardtail. And also i’ve found the box for the Sram pc-1130 chain and its only 114links, one thing I would say is Box’s own 11speed chain has only 116links

    https://www.chainreactioncycles.com/box-one-11-speed-chain/rp-prod178799

    I’ve just ordered the PC1130 with 120links so we shall take it from there and see what happens.

    dumbbot
    Member

    Although im not getting too hopeful yet, I’m definitely not liking the feeling of one of the levers on the shifter…

    Premier Icon dirkpitt74
    Subscriber

    Is the cable seated in the shifter correctly?

    Not sure what the box one is like but I had a SRAM shifter that was pain to get the cable in properly.

    dumbbot
    Member

    AS sure as I can be, you don’t open the shifter like a Sram just open a port on the side and thread it through.

    @ dumbot – Oh ok, that’s how it’s supposed to be. It does leave you with the option to swap that 2.5mm spacer over to the non-drive side, frame clearance allowing, if that helps!

    Chainlines were traditionally offset outboard in order for the chain to be straightest on the smallest most used sprockets. I’ve found further out to be more problematic, than further inboard! As long as the clearance is enough to prevent the chainring rubbing the chainstay or the chain catching the tyre, you can get very close without problems.

    greyspoke
    Member

    Too far in and when the chain is in the smallest cog it rubs on the next one in.

    dumbbot
    Member

    Ok so I ‘think’ I’ve got this sorted. A new 120link chain, replacement cables and new shifter. Basically what happened was running the chain too short put way to much tension on the drivetrain and borked the shifter and constantly mullered the derailleur hanger out of alignment (I purchased a hanger alignment tool). I possibly could stand to loose a link, but I’m loathed to fiddle with it further until I can actually ride the damn thing.

    So it shifts,but it wasn’t the easiest to get indexed and was quite fussy with b-tension but I imagine that’s similar to other 50tooth set ups. The shifting isn’t as crisp as my SRAM GX 11sp/Sunrace 46t… you seem to need to make quite positive, sharp thumb movements with the shifter or you get half shifts. I need to put miles in now.

    One thing I would say that Box components, UK distribution and the shop were really helpful and sorted my shifter in quick time.

    billyboy
    Member

    Boost set ups need a different chain line to 142 and 135. Using non boost chain line cranks with a boost system will cause problems. Look up what it should be and measure what you’ve got. The problems usually come at the extremes of the cassette depending on what the wrong combo is.. ie non boost crank with boost or boost crank with non boost.

    If you are using a Sunrace cassette, I personally have had issues with new Sunrace 8 and 9 speed cassettes causing gear change issues with delayed shifts and ghost shifts. It was only cured by replacing with Shimano cassettes. I’ve no experience of Sunrace 10 or 11 speed kit.

    tdog
    Member

    My 12 speed Sunrace kit with 50T biggest I’m sure came with a 126 link chain.

    dumbbot
    Member

    Sorry last one is a bit shit, but you get the idea of chain length. I don’t think i’d want it longer.

    Brief shakedown ride this afternoon, and yeah it does shift but as I stated above I feel i have to be much more conscious of how im pushing the shifter lever moving to the larger cogs, you need to be accurate and defined with your thumb movement or you shift too far/not enough. The clicks just seem vague compared to SRAM. Coming down from larger to smaller cogs seems to be much sharper. And ive played with cable tension/b tension till im blue in the face

    It’s hard to know if its a chainline issue or just a feel issue with the Box stuff.

Viewing 25 posts - 1 through 25 (of 25 total)

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