Fat tire bike mid-drive Conversions

[munirider]

I am getting ready to build a couple of fat tire e-bikes for me and my wife and found a couple of bikes that look suitable on craigslist. A good deal on a 26" Surly Ice Cream Truck. It looks like a great bike for a mid drive conversion and would be a good size for me.

And a Growler Performance Bikes for my wife, it looks like it would fit her well and comes with 27.5 wheels and narrower tires and the option for 26" wheels with fat winter tires.

They both look like good candidates for a build but I just wanted to get get some other opinions. I haven't ever heard of a Growler but it looks like a nice bike, aluminum frame and magura four piston brakes. Also it looks like it has good chainring clearance. The Surly Ice Cream Truck is a steel frame and it doesn't look as good for chainring clearance.

I was hoping that maybe m@robertson would chime in, I was thinking he has an Ice Cream Truck, but then I remembered it's a Big Fat Dummy that he has. Anyway I'm planning to use BBSHD kits with either a Luna cycle or Leki small front chainring. I'm going to go look at them and maybe buy them on Tuesday. I haven't ever done a fat bike conversion so any helpful advice would be appreciated.

 

[HumanPerson]

@ m@Robertson

Sometimes that doesnt work for his name lol

 

[munirider]

Thanks, accidentally put a t in there. I tried @ in front but it didn't work because of the misspelling.

 

[addertooth]

Those used bikes look rather nice, but for about the same price, you can buy a new fat wheel eBike already built.

What do you hope to gain by converting these bikes, as versus getting one already built?

 

[hugh]

Regarding the Surly conversion chainring clearance shouldn't be a problem. When you order your kit make sure to get a few spacers which will allow you to ensure the chainring does not abrade the chainstay. Thats what I needed to do when a BBSHD was added to my KHS 500 all season fatbike 8 years ago.
Addertooth has a point about buying a complete bike instead of converting. The cost of my bike plus the motor plus the battery added up just under $3,000. Still I wouldn't have it any other way, I get a sense of satisfaction knowing I modified and can repair it myself.

 

[m@Robertson]

Those used bikes look rather nice, but for about the same price, you can buy a new fat wheel eBike already built.

What do you hope to gain by converting these bikes, as versus getting one already built?

"for about the same price" would mean junk bicycle components and mediocre electrical bits - at best. No way, no how could you buy a new comparable bike with a decent motor and battery for that same price.

Magura 4-piston brakes alone are probably $250 for a set and thats if you know where to buy them direct for less than MSRP (but still from an authorized dealer).

 

[m@Robertson]

I am getting ready to build a couple of fat tire e-bikes for me and my wife and found a couple of bikes that look suitable on craigslist. A good deal on a 26" Surly Ice Cream Truck. It looks like a great bike for a mid drive conversion and would be a good size for me.

Surly Fat Bike - bicycles - by owner - bike sale - craigslist

I'm selling my Ice Cream Truck, size Large. This bike has giant 5" wide tires and is a blast in the snow (or sand, arroyos, etc). But it also rides great on regular trails, especially with the...

westslope.craigslist.org

And this bike, a Growler Performance Bikes for my wife, it looks like it would fit her well and comes with 27.5 wheels and narrower tires and the option for 26" wheels with fat winter tires.

Mountain, Bikepacking, Fat Bike - Growler Performance Bikes - bicycles - by owner - bike sale - craigslist

Up for sale is a do-it-all: mountain trails, bikepacking, fat bike from Growler Performance Bikes. I have two wheelsets; this one is a summer bikepacking / mountain bike setup. My winter 26"...

westslope.craigslist.org

They both look like good candidates for a build but I just wanted to get get some other opinions. I haven't ever heard of a Growler but it looks like a nice bike, aluminum frame and magura four piston brakes. Also it looks like it has good chainring clearance. The Surly Ice Cream Truck is a steel frame and it doesn't look as good for chainring clearance.

I was hoping that maybe m@robertson would chime in, I was thinking he has an Ice Cream Truck, but then I remembered it's a Big Fat Dummy that he has. Anyway I'm planning to use BBSHD kits with either a Luna cycle or Leki small front chainring. I'm going to go look at them and maybe buy them on Tuesday. I haven't ever done a fat bike conversion so any helpful advice would be appreciated.

I found the thread just by looking at the Whats New list

For the Surly, the ICT borders on a legendary bike. Its an excellent chromoly steel frame with a class-leading chromoly fork. You're right I own an electrified Big Fat Dummy but I have used Ice Cream Truck forks on my two AWD bikes with fat G060 hub motors and there is nothing like them for quality. Sadly I can't get the QR-dropout versions anymore.

For the Surly, your challenge will be the motor spacing. The ICT has a 100mm bottom bracket but forget about using a 100mm motor - the secondary housing will not clear the chainstays. Buy a 120mm motor and use a spacer to move it outboard so it fits. I have done this on two different bikes and it works a treat. BUT you will next need to use a large-offset chainring like a Lekkie. A Luna will be more offset but probably will not clear the chainstays. But a Lekkie Bling Ring probably will. If this is going to be an offroad bike, my choice would be to do the 40T motor cover+chainring package. That will let you use an offset chainring AND crucially move the chainline as far inboard as possible. Use an 11s drivetrain so you can have as many gear options as possible, and use a pie plate (46T or more) in back. Chances are you will not be able to get to the inner ring so the bigger range the better so you can land on maybe the 2nd one or even the third one from the top and still have good chainline. Other than dealing with these issues, the build will be completely straightforward.

Looks like the Growler will be the same story, but probably different spacers as the tire width and chainstays are all different.

 

[m@Robertson]

Regarding the Surly conversion chainring clearance shouldn't be a problem. When you order your kit make sure to get a few spacers which will allow you to ensure the chainring does not abrade the chainstay. Thats what I needed to do when a BBSHD was added to my KHS 500 all season fatbike 8 years ago.
Addertooth has a point about buying a complete bike instead of converting. The cost of my bike plus the motor plus the battery added up just under $3,000. Still I wouldn't have it any other way, I get a sense of satisfaction knowing I modified and can repair it myself.

He doesn't want to use a stack of spacers. They will shift over time. Been there/done that on fat frames with stays meant to clear 5" tires like the ICT has. Best is to use a single spacer that you have machined, which you can do via McMaster-Carr where you can order a custom-sized metric drill bushing. Or if you need exactly 10mm you can buy those cheap on Ali.

Here's one on a bike that is not as severe of a spread as the ICT has. This was in 2018. That bushing you see on the drive side came from McMaster. I ordered it to be a little less inside diameter than your typical bottom bracket spacer, which was part of the lesson learned about why you don't want to stack - there is enough slop in a BB spacer to cause a problem over time, so I solved it by knocking a millimeter off the ID and adding a couple mm to the OD so there was plenty of purchase between the frame and the motor. McMaster will not show me orders before 2020 anymore so unfortunately I no longer have the exact measurements, but I believe this was a 13mm wide spacer.

And this was a test fit for a bike I built in 2017. Similar issue 5" tires supported. I built the bike as you see it with these stacked spacers and they shifted, so I did I think a 9mm McMaster spacer on the drive side and a 10mm spacer on the non drive side that I got cheap from AliExpress.

 

[munirider]

"for about the same price" would mean junk bicycle components and mediocre electrical bits - at best. No way, no how could you buy a new comparable bike with a decent motor and battery for that same price.

Magura 4-piston brakes alone are probably $250 for a set and thats if you know where to buy them direct for less than MSRP (but still from an authorized dealer).

Exactly, this! I can buy a high end used bike and build it up the way that I want it, with better components, better battery, with the voltage and capacity I choose, and on and on.

 

[munirider]

I found the thread just by looking at the Whats New list

For the Surly, the ICT borders on a legendary bike. Its an excellent chromoly steel frame with a class-leading chromoly fork. You're right I own an electrified Big Fat Dummy but I have used Ice Cream Truck forks on my two AWD bikes with fat G060 hub motors and there is nothing like them for quality. Sadly I can't get the QR-dropout versions anymore.

For the Surly, your challenge will be the motor spacing. The ICT has a 100mm bottom bracket but forget about using a 100mm motor - the secondary housing will not clear the chainstays. Buy a 120mm motor and use a spacer to move it outboard so it fits. I have done this on two different bikes and it works a treat. BUT you will next need to use a large-offset chainring like a Lekkie. A Luna will be more offset but probably will not clear the chainstays. But a Lekkie Bling Ring probably will. If this is going to be an offroad bike, my choice would be to do the 40T motor cover+chainring package. That will let you use an offset chainring AND crucially move the chainline as far inboard as possible. Use an 11s drivetrain so you can have as many gear options as possible, and use a pie plate (46T or more) in back. Chances are you will not be able to get to the inner ring so the bigger range the better so you can land on maybe the 2nd one or even the third one from the top and still have good chainline. Other than dealing with these issues, the build will be completely straightforward.

Looks like the Growler will be the same story, but probably different spacers as the tire width and chainstays are all different.

Thanks exactly the advice I was looking for and thanks for the pictures. I hadn't even thought about the motor housing hitting the chain stay. Seeing what you are talking about helps a bunch. I am not in a hurry even though I would like to have them to ride right now. I'm sure I would have bought the 100mm motors.

It looks like the growler might have a bit longer chain stays and more room there for the motor gear housing and chainring than the ICT and I am pretty sure I will be able to but that one. The guy with the ICT is down in Santa Fe and is going to be showing it to a couple of potential buyers before I can get there. It looks like a really good deal at $1,300 with two sets of wheels and tires but I don't send deposit money to Crags list sellers, too many scammers out there, so we'll see.

 

[m@Robertson]

Yeah $1300 for an ICT is a smoking deal all by itself. Add in spare wheels/tires and thats a bike someone is pricing to get rid of. I can sympathize I am out of space and will be selling some of my bikes at fire sale prices as well. Speaking of which if 'munirider' refers to the SF Muni then maybe we can work a deal as I'm within driving distance.

 

[munirider]

Yeah $1300 for an ICT is a smoking deal all by itself. Add in spare wheels/tires and thats a bike someone is pricing to get rid of. I can sympathize I am out of space and will be selling some of my bikes at fire sale prices as well. Speaking of which if 'munirider' refers to the SF Muni then maybe we can work a deal as I'm within driving distance.

No, it's Munirider as in mountain unicycle rider, I spent a summer in SF forty years ago and so I have ridden that Muni.

I am in southwest Colorado, Ridgway. My folks lived in Salinas and now my Mom is in the Yosemite area, so I have spent some time around Monterey. I love that area.

 

[munirider]

Yeah $1300 for an ICT is a smoking deal all by itself. Add in spare wheels/tires and thats a bike someone is pricing to get rid of. I can sympathize I am out of space and will be selling some of my bikes at fire sale prices as well. Speaking of which if 'munirider' refers to the SF Muni then maybe we can work a deal as I'm within driving distance.

Well he didn't sell the ICT so I'm going to go check it out today. I think it's a good deal with two sets of wheels but not as good of a deal as you might think while I was waiting I looked to see the specs on the ICT and found that you can still buy one new and they are $1,999 right now. They are marked down from $2,349 so not that expensive even full price. He's had it for sale for 30 days now. https://surlybikes.com/bikes/ice_cream_truck

I will get it if it's all in good shape, the $700 less, no sales tax and the 29er wheels with 3" tires all add up to a good deal. I like the original frame better, they now have even shorter chain stays and a curved seat tube, They also now come with a 1/12 drive train and I would rather have the 11 speed that this bike has.

I did buy the Growler for $1,900, It was I think a better deal than the ICT, I am really impressed by what a nice bike it is. It is so light for such a fat bike. I haven't weighed it yet but wow. And everything on the bike is perfect not a scratch on anything. And both sets of wheels and tires are perfect as well. It has vinyl that matches the paint covering most of the frame for protection. The Growler was $3,500 new plus the extra set of wheels with tires would have probably cost another $1,000.

 

[m@Robertson]

Well when I said 'good deal' I was taking into account the strong aftermarket for those bikes. I wasn't aware of them being discounted but I'm not surprised since the market sucks right now and its a buyer's market. Join the Surly Owners Group on Facebook and you will see it is a) huge and b) those bikes are both a bike and a lifestyle statement to their owners.

 

[munirider]

Well when I said 'good deal' I was taking into account the strong aftermarket for those bikes. I wasn't aware of them being discounted but I'm not surprised since the market sucks right now and its a buyer's market. Join the Surly Owners Group on Facebook and you will see it is a) huge and b) those bikes are both a bike and a lifestyle statement to their owners.

I can see why, I got the bike yesterday for $1,200 It's pretty cool! Those 5" tires are so fat! I'm now not so sure it will work for an e-bike conversion though . The bottom bracket is 130mm wide. He thought it was a 2016 or 2017, it has through axles front and back. Any suggestions?

I see that CYC goes up to 120mm wide as well, they say, 68-83mm, 100mm, and 120mm


Possible options:

Sell this ICT and buy a new ICT for $1,999 (the new frame has a 100mm BB)

Buy a new frame and use all the parts off the ICT then sell this frame.

Modify this frame to make it work with a 120mm motor by grinding off 10mm from the left side of the BB. (take it to a machine shop)
I would first put the 120mm motor I buy for the Growler into the BB to see if the motor housing clears the frame before doing this.

 

[m@Robertson]

Yeouch. Now that you mention it I do remember the older ones had goofy bottom brackets.

If you go the machine shop route, take 5mm off each side, not 10mm on one side. BUT the chainstay roots look just as wide as I remember... Think thru this. You probably can get a 120mm BBSHD motor to come close to clearing. But if you do, you'll need to use a small 36T chainring as I seriously doubt there will be clearance for a 42T or even a 40T with 5mm less bottom bracket on one side to help your motor clear. I think the motor fitment may be do-able but when you get to the next phase you are going to end up with a very nice, small front ring, but chain alignment that only allows use of the smallest 5 or 6 cogs at best.

I think you have a good plan re: using the existing motor you have to check fitment and troubleshoot.

If I were to guess, it would be best to keep the bike intact for sale. In the meantime you can ride it and have fun with it.

If you can make it fit with some judicious (professional!) machining, a 36T front ring on a BBSHD is actually quite awesome. Mine enables me to pretty much climb anything. The fact the longtail frame puts my rear wheel in another time zone doesn't hurt either but still that front ring is the proverbial game changer for slow, brutal climbs.

 

[m@Robertson]

Also, google tells me Tree Fort has ICT's on sale for $1649.

 

[munirider]

I'll have to look at that. Thanks. I could easily sell this bike I think for $1,000 with just the fat wheels.

Then buy a complete new ICT for $1649

I would rather have the 10 speed this bike has than the 12 the new bikes come with, but there's always compromises.

 

[munirider]

I think your right about keeping this bike intact, selling it and just starting over.

I could get more if I sell the second set of wheels separately, they are 29ers in good shape with Salsa through axel hubs, 50mm Surly rabbit hole rims and 3" tires. I may keep them but I don't see myself ridding this bike much except in the winter months.

 

[m@Robertson]

My Surly My Other Brother Darryl wheels also have Salsa hubs. They are the stockers that came with the BFD. If you have 29er MYOBD rims, do yourself a big, fat favr and do NOT try and remove the tires from the wheels. My own MYOBD wheels are so difficult to remove tires on, for the first time in my life I took them to the LBS to switch tires for me. The mechanic there told me they were the most difficult rims he had ever worked on. FYI they lack the depressed center channel most rims have to make tire removal... possible. It is 100% of the reason I built up a second set of wheels for the BFD... I knew roadside repair was impossible with the MYOBDs and I can't have that.

Good move on staying away from 12s on a mid drive bike. Its a bridge too far. 11s is fine with the right equipment (Sunrace CSMS7 pinned steel cluster) but 10s is a newer (cheap) option via the Microshift Advent X derailleur, shifter and 11-46T steel pinned cluster. Its what I use on my Bullitt hill climber and it takes brutal punishment, trouble-free.