I've just set up my drivetrain 1x10 with 32t hope retainer ring and 40t rex cassette extender.
I was expecting the drivetrain to be much quieter but when on the big sprocket at the back the chain makes kind of jumping grinding noise as it leaves the cassette.
The shifting is fine but if I pedal backwards the chain falls onto the middle of the cassette.
I set up using an XT cassette taking out the 17t sprocket and spacer and an XT double placing a spacer on the drive side of the BB to compensate for the loss of the direct mount etype front derailleur and placed the 32T ring where the larger of the double chainrings would go.
Do you not want to [i]remove[/i] spacer from the drive side if you're using the large ring position?
shouldn't have to adjust the spacer at all... just leave it as it should be....
ie:
1 on the drive side for a 73mm
2 on the drive side and one on the non-drive side for a 68mm
a triple crank has better positioning of the middle chain ring vs the double, so seems to be the preferred option (from what i've read on here).
i'm using an XT double crank with a General Lee 42T sprocket setup and it works perfectly now, though it was quite a faff to get setup initially.
Check B tension where it goes onto the 40t cog. It could need extra gap if it's grinding. Failing that it's a chainline issue of some sort. As said triples convert better to a single than a double. Though if your crank can swap out the spider for a single then that's a good solution (as my X0 could. I just got an X0 DH spider).
Shifting generally might be more of a clunk down and a grind up though just because it's a big step between (I assume) 40t and 36t. I've heard a few people comment that it's not quite a smooth shift.
I had a similar set up which was working fine until my bike shop touched it and starting making a similar noise to what you describe in 1st. Turned out they'd wound the b screw in too much and increased the chain tension. Wound it back out so mech moved closer to the cassette and all is silent again.
Also, they tend to drop when pedalling backwards for a handful of rides until it all beds in, especially with a new chain
I swapped a spacer to the nds to get a better chain line on mine. Just make sure you have the right number of spacers in total. So you would add one if you remove a bb spacer front mech or chain guide.
robgclarkson
i'm using an XT double crank with a General Lee 42T sprocket setup and it works perfectly now, though it was quite a faff to get setup initially.
What were the difficulties? I have set the B limit screw as per Hope's instructions and the upshift is fine but the sound on the t rex is not good.
The H/L limit screws are fine.
getting the b tension right, and getting a smooth shift both up and down... i can't really tell you 1 specific thing that i did to get it right, but it suddenly just 'clicked' after several tries of getting the cable tension right, setting H/L time and again, then fine tuning with the screw on the shifter...
it's worth pointing out that on the 11t cog i've only got 3 and a bit cogs actually covered by the chain due the amount of b-tenison i had to put on, but my setup is a 42t large cog, not a 40t one like yours, so you shouldn't need the same as me...
Just to say again also look at the chain line, your running from further to the right than you would normally for that gear.
As said above. The middle position of a triple is in the middle of the chain line with the inner and outer set 5mm either side.
A double has the inner and outer 5mm apart but set either side of the midline, ie +/- 2.5mm. So if you run your single ring on the outer of a double spider, your chain line on the inner cogs is suboptimal. Not disastrously, but sub.
You can compensate by moving a 2.5mm spacer from the drive to non drive side of the bb - then your chain line is back in the middle but you cranks are offset. But you'll never notice. Or, I have heard you can space the chain ring back in with spacers.
Lastly, I believe (never proven, just musings) that the way that these nw rings work, with the teeth being a tight tolerance to the chain inner plates, means that when at extremes of crossing there is more interference with the chain leaving the chainring, whereas on a normal ring there's a bit more space for the chain to run at an angle before it starts to rub on the chain ring's teeth. Hence noisier and more prone to unshipping when you back pedal.
Thanks for all the information singletrack massive.
I think I'm going to try moving the spacer to the non drive side and see how it goes from there.