Exchange 120mm BBSHD for 100mm (chainline concerns)?

[CCroft]

OK, so I'm doing a BBSHD build on a fatbike model with no prior builds for guidance. I measured carefully, posted some threads, got some advice, and ultimately decided the 120mm size was the 'best bet' due to concerns about clearing the chainstay. Good news is there's no issue with the chainstay (using just one narrow spacer on the drive side). Bad news is that I've got at least 15mm of unthreaded tube on the nondrive side. Don't the BBSHD lock rings need to butt dirtectly up against that bottom bracket to be secure, rather than butting up against spacers? Problem is if I put those spacers on the drive side I've got an even worse chainline situation. These pics show the chainline with my Luna Eclipse 36T front ring and chain on the 37T ring of my Shimano XT 11-46 rear cassette.

Should I exchange this 120mm for a 100mm? I assume I'd still have plenty of 'thread' on the nondrive side to tighten down everything correctly? Or maybe I'm wrong about being able to tighten the lock rings up against spacers on the nondrive side rather than directly up against the edge of the bottom bracket? Obviously my 'Q factor' or whatever would be lopsided to that nondrive side, but with the kind of off-road riding I do with this bike, I'm not thinking that would be an issue.

 

[tomjasz]

It’s best to not have spacers between the fixing plate and bottom bracket. I never liked using spacers unless absolutely necessary. Unbalanced crankarm distances don’t bother those heavy throttle guys but make me nuts pedaling. If 100mm is a better fit exchange it. OR you could use a stabilizer and keep the motor from dropping. Luna tends to be slow with exchanges and it does get expensive shipping. Next, consider whether you might upgrade the bike someday and want a 120mm. If the motor is scuffed in any way no one like returns.

the last picture looks like you’ll be throwing your chain on the largest gears.

 

[CCroft]

Hi Thomas and thank you for your thoughts. You make a good point about using this 120mm on other bikes and I have thought of that. I was able to find a few threads here and on ES where folks have placed spacers in between the fixing plate and the lock ring to 'shim' a gap like I have, so it does look like I can make this 120mm 'work' assuming I can live with that unbalanced crankarm distance like you say.

Do you have idea what kind of metal pipe one could use to make their own 'spacer' for a situation like this? I think I'd prefer to go that route rather than a bunch of smaller spacers. I'm going to take the drive with me into the hardware store this afternoon just to make sure of the fit, but looks like some pipe with an ID of around 1.25" (maybe a bit more) is what I would need--and with a thick enough wall so that the lock nut can get a good 'bite.'

 

[CCroft]

One other question. Are folks aware of any kind of insert, crank, etc. that could be used on the drive-side in situations like to extend that crank "outboard" a bit to help "balance" the crankarm distance?

 

[tomjasz]

Do you have idea what kind of metal pipe one could use to make their own 'spacer' for a situation like this? I think I'd prefer to go that route rather than a bunch of smaller spacers.

There are Bottom Bracket Spacers that are wider available.

One other question. Are folks aware of any kind of insert, crank, etc. that could be used on the drive-side in situations like to extend that crank "outboard" a bit to help "balance" the crankarm distance?

I can't imagine why anyone would create such an adapter. There's a company around that did odd adapters. I think they were called Problem Solvers. Yes, they have a website. If anyone has a solution it would be on their list!

Collections

Problem Solvers

problemsolversbike.com

 

[tomjasz]

few threads here and on ES

Luna has a forum. www.electricbike.com/forum
You'll find lots of advice and builds like yours there.

Have you tried Google? With every customer I always use google to find any builds with the same bike that may be posted.
For example, 2019 Surly Ice Cream Truck BBSHD

Most of the time I find other builds and can read about issues and how they may or may not have been solved.

LMGTFY - Let Me Google That For You

For all those people who find it more convenient to bother you with their question rather than to Google it for themselves.

lmgtfy.com

 

[CCroft]

Yes, I'm aware of Google, and I've reviewed/searched Luna's forum and even posted this particular issue there (and on ES). As I mentioned at the beginning of my post, there was no prior build on my specific bike (Growler Mr. Big). What someone did with a Surly Ice Cream Truck is interesting, but not necessarily relevant. Searching for this particular issue ('chainstay' 'spacers' 'BBSHD') yielded a few threads, but not a lot on the issue I initially posted on. Since posting I've search/poked around some more and found some additional information.

I really don't appreciate your implication that I lazily "bothered you with my question" rather than searching for it myself ("LMGTFY"). If you can refer me to a specific existing thread, website, etc. that specifically answers/addresses my specific question initiating this thread, please share. My initial question was/is fundamentally an opinion one: should I keep or exchange the 120mm BBSHD based on what I was encountering with my specific bike. I posted decent photos in the hopes of getting some opinions of ebikers/builders with experience, which I thought was the point of a forum like this. The "answer" to that question is not going to be found through a Google search as you suggest, and certainly for a model that isn't even mine. Nor could I find specific answers for my subsequent specific questions (pipe "spacer" size, crank widening options, etc.).

Luna has a forum. www.electricbike.com/forum
You'll find lots of advice and builds like yours there.

Have you tried Google? With every customer I always use google to find any builds with the same bike that may be posted.
For example, 2019 Surly Ice Cream Truck BBSHD

Most of the time I find other builds and can read about issues and how they may or may not have been solved.

LMGTFY - Let Me Google That For You

For all those people who find it more convenient to bother you with their question rather than to Google it for themselves.

lmgtfy.com

 

[tomjasz]

Yes, I'm aware of Google, and I've reviewed/searched Luna's forum and even posted this particular issue there (and on ES). As I mentioned at the beginning of my post, there was no prior build on my specific bike (Growler Mr. Big). What someone did with a Surly Ice Cream Truck is interesting, but not necessarily relevant. Searching for this particular issue ('chainstay' 'spacers' 'BBSHD') yielded a few threads, but not a lot on the issue I initially posted on. Since posting I've search/poked around some more and found some additional information.

I really don't appreciate your implication that I lazily "bothered you with my question" rather than searching for it myself ("LMGTFY"). If you can refer me to a specific existing thread, website, etc. that specifically answers/addresses my specific question initiating this thread, please share. My initial question was/is fundamentally an opinion one: should I keep or exchange the 120mm BBSHD based on what I was encountering with my specific bike. I posted decent photos in the hopes of getting some opinions of ebikers/builders with experience, which I thought was the point of a forum like this. The "answer" to that question is not going to be found through a Google search as you suggest, and certainly for a model that isn't even mine. Nor could I find specific answers for my subsequent specific questions (pipe "spacer" size, crank widening options, etc.).

Relax fella. I have no idea as to where you’ve posted or what your skill level is. I posted as I would with anyone I dont know. You show as a new member and I haven’t read any introduction. Numerous times every day I get support calls from nice folks that this is all new to. I start with the basics. I don’t imply anything. As you get to know me you’ll discover I do not pull punches. I won’t imply anything. I’ll say it straight out. There was no malice or intent to suggest you were lazy. Unfortunately you read that into my response.

You are misreading my intent. I used the Surly as an example since I haven’t read all your other forum queries and haven’t any details as to which bike you have. I intended to be polite and helpful. I’m sorry my approach wasn’t what you expected. Frankly it takes a lot of time to sometimes help posters here. I have a plate full of people I assist daily. Believe me when I tell you the average support customers never give a thought to a search string using their bike model, brand, year, and motor choice. If my commissions were earned on a sliding scale reviewing customers knowledge level after I did their research I’d be fat and happy. As it is I help because it’s fun and invariably i learn more and I add another bike to my data base.

By the way, I sorted 3 builds today by using google search strings. Found two solutions I hadn’t considered and saved a customer from buying a bike that would have been a kit nightmare. I suggest my customers search thoroughly for the bike they are considering, with all the details, before jumping in and finding they’ll have an unbalanced pedals, cranks, a useless chainline, or any number of other issues.


Peace. My apologies, Let’s try again....