My UC Pro has arrived

[linklemming]

I think they're a standardized part.

Yes, they are standardized as far as diameter but can vary on length depending on what they are being used for (single vs double chainring). Forgive me if you already knew that, just clarifying

You can even buy some that come with spacers (I have bought these)
Chainring Bolts with spacers

You can even buy all sorts of different chainring spacers.

It might take a few orders/trial fits to get exactly what is needed. I have quite a collection

 

[Deacon Blues]

I'm wondering if going to a spider with a greater offset might also work.
I have no idea what the stock Bafang spider offset is and I have no idea where I'd order a spider with more offset.
Also, I guess I'd need a tool to pull the arm arm and the bottom bracket bolt. Is the bottom bracket bolt specific to a Bafang setup?
Any help/links would be greatly appreciated.

I'm thinking the spider with more offset might be the way to go, since I'd like to move the chainring out 2 cassette cog spaces, so the front chainring lines up with the #5 or #6 cassette cog.

 

[Fast n' Furious]

I'm wondering if going to a spider with a greater offset might also work.
I have no idea what the stock Bafang spider offset is and I have no idea where I'd order a spider with more offset.
Also, I guess I'd need a tool to pull the arm arm and the bottom bracket bolt. Is the bottom bracket bolt specific to a Bafang setup?
Any help/links would be greatly appreciated.

I'm thinking the spider with more offset might be the way to go, since I'd like to move the chainring out 2 cassette cog spaces, so the front chainring lines up with the #5 or #6 cassette cog.

I use a Park CWP 7 to pull my cranks.
I suggest a universal Pedro https://www.modernbike.com/product-...f4xpZzLMfQev6R3E1R8rGxDR6rWtF6jxoCJqcQAvD_BwE
I like this company (in USA - but you're in BC right?). Everything I obtained from them has been by far the lowest prices and quick delivery of exactly what I ordered.
The splined nut can be removed with the proper tool (splined socket).
Measure the stock offset? I'd ping this guy https://electricbikereview.com/forums/members/theemartymac.36918/ .
He has a lot of experience with the Ultra. Read this topic https://electricbikereview.com/forums/threads/bafang-ultra-drivetrain-wear-experience.42246/

This guy also knows the spiders, specs and rings that fit - inside out https://electricbikereview.com/forums/members/m-robertson.42150/
They're running 9speeds, but you only care about the offset facts.
How wide are your bikes dropouts? You must find that first. The values for offsets required vis a vis frame width, are published.
Don't limit yourself. Use any chainring with bling. You want this https://www.ebay.com/itm/194233531522 . It's cut to be18mm distance from base to inside of chainring and you can use the ring gear on the outside (omitting the bash-ring) if that's wide frame and either way you can use one of a million other type current, common hi lo rings, from 44 - 48T with ease - and super economy.
You're gonna eat drivetrains. You went chain for being able to get back up in a flash. You'd be in big trouble w/ a K-nay. It's gonna break too.
Belt drive is waaaaay more sensitive to alignment.
If the 6mm additional offset from reversing the spider didn't work, only Christini makes your stuff.
I'm not talking about moving the ring gear to the outside of the spider, I'm saying remove the spider - which takes the special tools listed above - and reverse it so the spider's arms face outward, not inward (stock) then reinstall.
Look closely at your spider. Is the curve of the arms inward or outward?
My understanding is with "Boost" widths it must be outward and is designed as such.

Hope this helps

 

[Deacon Blues]

Thanks Fn'F. Lots of very helpful information!

 

[Deacon Blues]

With the chain ring now sitting on the outside of the spider I took the bike for a short ride.
Some comments:
1. in power level 2 and with the cassette in the 3rd cog I could not get the chain to skip.
2. I could get the chain to skip in the 1st and 2nd cogs.
3. This bike is Very comfortable and VERY fast. In level 2, with a bit of effort I was able it hit 27mph!
I plan on decreasing the wattage output. I really don't need the motor to be uncorked. I'd probably be happy with 1000W and my cassette/chain would thank me.

 

[Fast n' Furious]

Thanks Fn'F. Lots of very helpful information!

Probably no need for a new spider
View attachment 106609

Can't he entire spider be reversed with the arms facing inward - for narrower frames - like the UC's ?
I read that reversing (as above, Left Picture) spider is for 'boost' sizes.
Trying to gain more for big offset fat-bikes leads to using the bash guard position/ spacers. I'm thinking that's 197mm+ stuff.

Thanks Fn'F. Lots of very helpful information!

Here's some more and there's your tools https://support.biktrix.com/hc/en-us/articles/360041970951-How-to-remove-an-Ultra-Motor-from-Bike

 

[Jon A]

I'm thinking the spider with more offset might be the way to go, since I'd like to move the chainring out 2 cassette cog spaces, so the front chainring lines up with the #5 or #6 cassette cog.

I agree. I'd suggest measuring your rear hub to be 100% sure what spacing you have. I can confirm if it's 197, both the Christini "FAT" and the stock Bafang "Fat" spiders will put the chainline right in the middle of the cassette with the chainring mounted to the outside.

One more thing--could you post a side view pic of your derailleur in the smallest cog? It's hard to tell from the other pic, but it looks to my eyeball like the chain isn't getting much of a wrap around the small cog which could certainly make it easier to skip teeth. Some B-screw adjustment might be able to improve this if that's the case.

 

[Merle Nelson]

I'm wondering if going to a spider with a greater offset might also work.
I have no idea what the stock Bafang spider offset is and I have no idea where I'd order a spider with more offset.
Also, I guess I'd need a tool to pull the arm arm and the bottom bracket bolt. Is the bottom bracket bolt specific to a Bafang setup?
Any help/links would be greatly appreciated.

I'm thinking the spider with more offset might be the way to go, since I'd like to move the chainring out 2 cassette cog spaces, so the front chainring lines up with the #5 or #6 cassette cog.

Not sure, but I think @Cuz Vinny could nail this issues solution with his eyes closed. If I had it to deal with I'd be asking him exactly what he would do.

Sorry your having to work through it now.

 

[Ebiker33]

Glad you got your Ebike, now if there are gas shortages on the island you have a second mode of transportation that is high end.

 

[Deacon Blues]

Jon A, I did have the bike mechanic at the shop that does work for me look at the bike. The B screw is as close to the cassette as it will go without making contact, so he didn't need to adjust it.
I'll have to ask Pushkar what the rear hub spacing is, as it's impossible to measure it with the wheel on.
I will have the wheel off in the next few days when I swap out my 11-50 cassette for a Shimano 11-42. Anyone have an idea as to how many chain links I'll have to take off?

 

[Cuz Vinny]

Not sure, but I think @Cuz Vinny could nail this issues solution with his eyes closed. If I had it to deal with I'd be asking him exactly what he would do.

Sorry your having to work through it now.

This is what I did for both of my bikes. May not work for everyone but it works for me.

Large front chainring, 44T, mounted on the outside of the adapter
Shimano 10 speed cassette with the 11 and 13T cogs removed. Spacers used to push the cassette outward.
Shimano XT 11 speed derailleur (10 speed should also work)
KMC ebike chain (136 links, links removed to make fit, keep it snug)
Adjust rear derailleur to keep the chain tight, no sag
Frame protection in the vulnerable area on the swing arm, I use AMS.

This will reduce your top speed to a 25 - 30 mph bike. If that’s an issue for you then I’d look elsewhere. The chainline on the bikes isn’t 100% perfect but it’s a lot better than originally. Plus I have zero skipping. Hope this helps.

 

[Fast n' Furious]

I agree. I'd suggest measuring your rear hub to be 100% sure what spacing you have. I can confirm if it's 197, both the Christini "FAT" and the stock Bafang "Fat" spiders will put the chainline right in the middle of the cassette with the chainring mounted to the outside.

One more thing--could you post a side view pic of your derailleur in the smallest cog? It's hard to tell from the other pic, but it looks to my eyeball like the chain isn't getting much of a wrap around the small cog which could certainly make it easier to skip teeth. Some B-screw adjustment might be able to improve this if that's the case.

But only the Christini will allow most off the shelf ring gear versatility. Already on my CT's build improvements list.
Good point. Consensus is starting high gear cog should be 12t to minimize wrap problems. 13t provides the same 6 teeth engaging the chain as 12t, but 11t grabs only 5. So a 12t has 20% more teeth on the chain. 20%'s big in my mind.
I'd change out for a 10% increase in cog grip. 14t would be even tougher, but chops MPH off the top end.
With that Christini, monster size rings will fit w/ that huge offset.
The option of going with larger clusters = more chain on the teeth. 14t is now in the picture. 7 teeth transferring power, 40% stronger.
I anticipated WW would have this worked out.
If I have to do it all myself, may as well delete the useless parts and bring the price down so I can do it right.

Fn'F

 

[loamoaf]

Looks like the Christini is the way to go. Chainring inside the spider for 177mm, outside for 197mm. The way the Wolftooth mounts on my spider it's looking like I may have to grab little spacers to get it on the outside of the spider with clearance. It has offsets built into the chainring for mounting inside, or placing a guard on the outside, but it needs spacers on the other side - I wish it was symmetrical and had offsets on both, oh well. Can't just flip it because the dropstop tooth profile is direction. The Christini fat spider + 30T stainless steel ring weigh 186g. Gap with the built-in standoffs facing measured at 1.75mm, SRAM EX-1chain (10-spd width) clears it fine, so an 11-spd should as well. You need the long Wolftooth bolts to engage enough threads on the chainring, any longer chainring bolts with M8 x 0.75P threads.

I will agree with Fn'F on this one - for your max speed you'll want to max out the size on your chainring so you canhave a 13T or larger smallest cog. The different derailleur cage (or M8100 derailleur) would also help getting more wrap on the smallest. Think about this, if you are hitting 200Nm that's like Honda Civic torque. Is it realistic to expect a little 6-7 teeth of engagement on a cog to handle that without protesting a little bit? Detuning the motor is also probably smart. More range, more work out, live longer to ride your Watt Wagon!

 

[Johnny]

I will have the wheel off in the next few days when I swap out my 11-50 cassette for a Shimano 11-42. Anyone have an idea as to how many chain links I'll have to take off?

You shouldn't change the number of links. Your previous chain is already working in the range of cogs in 11-42 cassette, since it is a subset of 11-50 so things should be fine.

 

[Deacon Blues]

Thanks for all the info, guys.
Looks like the Chrisiini spider is the way to go. Now the hard part......trying to find one.

 

[Deacon Blues]

Damn!

 

[loamoaf]

@Deacon Blues rough luck! Keep an eye his ebay store profile. Doesn't look like he has any up there but that's where I found them in stock when his site's store did get the stock status updated. Stay strong! You can try with just spacers and longer chainring bolts but that's not ideal. There's the lame steel stock Bafang fat spider that can be found online - it's not necessary to get the 104 BCD Christini if you don't want a smaller front chainring. I may not have my X1 yet but I'm feeling pretty fancy having a different item that seems to be in limited supply hah!

 

[loamoaf]

Aye I forgot to add, if you peep the diagram in this thread on ES you can see the fatbike spider is 22mm offset from the standard. Credit goes to Daxxie for that post

 

[Jon A]

The B screw is as close to the cassette as it will go without making contact, so he didn't need to adjust it.

OK, that might just be how that derailleur ends up with that cassette. With the new cassette you may be able to tighten things up a bit.

I still think a pic might be instructive for comparison purposes though for others chasing down this issue. I took a look at mine when I saw your pic (mine is a Sram 12-speed) for comparison:

A more straight on shot:

My motor doesn't have the X1 controller (which is why I was asking about power levels earlier) so it's "only" 1500W peak. But I have quite a few miles on that wheelset with an 11-tooth and my other wheelset with a 10-thooth small cog and I've never gotten a skip in the small cogs. Most of the miles have been in lower power modes but I've done quite a few full throttle blasts to the point I feel confident in the setup. I certainly wouldn't expect those cogs to last forever under commuting use (I'd get a bigger chainring for that) but for my more occasional use it works well so far.

But only the Christini will allow most off the shelf ring gear versatility.

That's certainly true; I mentioned the stock one as it's hard to find parts these days. They're within a mm or two of each other IIRC, so in case he couldn't find one he could use the other.

Credit goes to Daxxie for that post

Excellent find indeed! As expected, it looks like the default Bafang "MTB" version of the motor ships with a chainline correct for a regular, non-boost 142mm hub. That should be expected to cause issues with some frames (and tire clearance) on boost bikes.

 

[Deacon Blues]

Can anyone give me a link to an online source for the Bafang fat spider?
I'm okay with the size of the chain ring for now. If I were to ever change it I'd go larger.

In one of my conversations with Pushkar he mentioned that one of solutions to solving the chain skipping would be to replace the 11-50 cassette with a 11-42. Can someone explain to me why going to a smaller cassette would be beneficial?