DIY handlebar shim ideas? Using 22.2mm Moto-x bars (same diameter as BMX) in my 31.8mm stem

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ben2401   1 mW

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DIY handlebar shim ideas? Using 22.2mm Moto-x bars (same diameter as BMX) in my 31.8mm stem

Post by ben2401 » Apr 02 2021 4:45pm

Hey, building up my 2004 Rocky Mountain Switch with a rear 1500W DD hub (CSC kit off Aliexpress). Got some 765mm wide steel two-piece moto-x bars that I want to run in the integrated Marzocchi 31.8mm stem on my Super T fork. Can’t just use a BMX stem otherwise I would. Found a Problem Solvers SM5700 22.2-31.8mm adapter which might work (supplied with many Ti bars as well because they are mostly 22.2mm, also supplied with Surly Sunrise bars) but it’s about 40$ with shipping for an aluminum shim. Any diy ideas?
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ben2401   1 mW

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Re: DIY handlebar shim ideas? Using 22.2mm Moto-x bars (same diameter as BMX) in my 31.8mm stem

Post by ben2401 » Apr 02 2021 4:49pm

BTW the bar is just temporarily mounted with rubber spacers for 22.2-31.8mm (for mounting accessories, not tight enough to hold the bar under serious force).

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Re: DIY handlebar shim ideas? Using 22.2mm Moto-x bars (same diameter as BMX) in my 31.8mm stem

Post by LewTwo » Apr 02 2021 5:32pm

One might try increasing the diameter of the center of the handle bars by wrapping the mounting point with 4 inch wide fiberglass tape and epoxy (not polyester) resin. After it has set, you could sand the two ends down to a taper for aesthetics. Hint: use black tint is the resin.
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Re: DIY handlebar shim ideas? Using 22.2mm Moto-x bars (same diameter as BMX) in my 31.8mm stem

Post by MadRhino » Apr 02 2021 6:03pm

Stem/handlebar adapters are not expansive normally. For quite some time they were included with many stems and its is not uncommon to find some in junk boxes at bike shops. On Aliexpress they are 2$.
Make it fool-proof, and I will make a better fool.

ben2401   1 mW

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Re: DIY handlebar shim ideas? Using 22.2mm Moto-x bars (same diameter as BMX) in my 31.8mm stem

Post by ben2401 » Apr 02 2021 8:03pm

MadRhino wrote:
Apr 02 2021 6:03pm
Stem/handlebar adapters are not expansive normally. For quite some time they were included with many stems and its is not uncommon to find some in junk boxes at bike shops. On Aliexpress they are 2$.
Thanks, I will look around at the shops here and barring that get some shims off Aliexpress.

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Re: DIY handlebar shim ideas? Using 22.2mm Moto-x bars (same diameter as BMX) in my 31.8mm stem

Post by ben2401 » Apr 02 2021 8:12pm

LewTwo wrote:
Apr 02 2021 5:32pm
One might try increasing the diameter of the center of the handle bars by wrapping the mounting point with 4 inch wide fiberglass tape and epoxy (not polyester) resin. After it has set, you could sand the two ends down to a taper for aesthetics. Hint: use black tint is the resin.
Not a bad idea if I can’t find/make a shim that fits. You think fibreglass will be hard enough to get a good grip from the stem? Can it handle being cranked down on without cracking?

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Re: DIY handlebar shim ideas? Using 22.2mm Moto-x bars (same diameter as BMX) in my 31.8mm stem

Post by MoneyPit » Apr 02 2021 8:20pm

Shims are cheap, and they have features like horizontal ribbing that uniquely suit them to their job on a mission-critical part. If the bars slip you could be up for new teeth at worst or just constantly pissed off that every time you grab the bars hard they move. Or spend like $6 on eBay. Thats where I get mine.

Worth mentioning is I've been there and done that. I used some alloy tubing that I sawed in half. Without that ribbing you can clamp the bejesus out of the bars all you want and they'll still move.

If you are committed to DIY for the sake of adventure... weld it into the stem.

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Re: DIY handlebar shim ideas? Using 22.2mm Moto-x bars (same diameter as BMX) in my 31.8mm stem

Post by Eastwood » Apr 02 2021 9:09pm

ben2401 wrote:
Apr 02 2021 4:45pm
Hey, building up my 2004 Rocky Mountain Switch with a rear 1500W DD hub (CSC kit off Aliexpress). Got some 765mm wide steel two-piece moto-x bars that I want to run in the integrated Marzocchi 31.8mm stem on my Super T fork. Can’t just use a BMX stem otherwise I would. Found a Problem Solvers SM5700 22.2-31.8mm adapter which might work (supplied with many Ti bars as well because they are mostly 22.2mm, also supplied with Surly Sunrise bars) but it’s about 40$ with shipping for an aluminum shim. Any diy ideas?
I actually have some BMX handlebars mounted in a 31.8mm stem. I have these installed on a standup bicycle. I didn’t use spacers and basically sanded down the front plate of the bar stem so it would pinch the handlebars.
Maybe this would work in your situation…
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Eastwood   100 W

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Re: DIY handlebar shim ideas? Using 22.2mm Moto-x bars (same diameter as BMX) in my 31.8mm stem

Post by Eastwood » Apr 02 2021 9:21pm

ben2401 wrote:
Apr 02 2021 4:45pm
CSC kit
Also bought the same kit. My top speed was 31 mph in a 27.5” wheel with the stock controller and 48V battery. The controller does tend to get fairly warm after long rides. I was pushing around 40amps. The motor doesn’t have the best torque off the line but has decent torque in the mid range. I’m not sure if you bought your battery yet but I would at least use a 52v

I’m still using that motor with 84V battery 60amps bms. It now hits 50mph but got to keep a watch on the heat buildup.

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Re: DIY handlebar shim ideas? Using 22.2mm Moto-x bars (same diameter as BMX) in my 31.8mm stem

Post by ben2401 » Apr 02 2021 10:58pm

Eastwood wrote:
Apr 02 2021 9:21pm
ben2401 wrote:
Apr 02 2021 4:45pm
CSC kit
Also bought the same kit. My top speed was 31 mph in a 27.5” wheel with the stock controller and 48V battery. The controller does tend to get fairly warm after long rides. I was pushing around 40amps. The motor doesn’t have the best torque off the line but has decent torque in the mid range. I’m not sure if you bought your battery yet but I would at least use a 52v

I’m still using that motor with 84V battery 60amps bms. It now hits 50mph but got to keep a watch on the heat buildup.
Also have a very similar Pasion ebike kit (26” MTX39 rim, sine wave KT controller, had a couple nice touches like a Shimano freewheel and brake rotor and XT90 and XT150 connectors, but it has gone up too much in price though to buy again) on a hard tail dirt jumper (Specialized P2), which is the first ebike I’ve had or converted, in 2019. Been using that with 48V 13s6p setup that works fine at 100% current setting for ~2000W (45A according to the controller specs). Get 55-60km/h out of it maxed out which is fast enough on a hard tail for me. Agree that higher volts would be better but the controller and display from the kit are only good to 52V. Really like the KT controllers and displays and there is a cool open source firmware project here on ES. Went with 48V for availability of cheap 13s3p Chinese scooter packs for 100$ each and using two in parallel with a homemade XT90 harness. No issues over two years. Got a crazy good deal on two 13s4p packs which I’m going to use in parallel for 13s8p for this bike. Maybe a backpack battery but that could be too much weight, not sure yet. The CSC kit is very similar although it came with a dual-mode KT controller, both are 18-mosfet. The dual mode isn’t quite as quiet as the sine wave but has the nice feature of working without hall sensors in case of their failure.

Comparing the motors between Pasion ebike and CSC, they seem to be identical. Motor casings are the same except with different engravings/serials and look exactly like the 1500W Leafbike motors except with 2.5mm^2 phase wires instead of 3.0mm^2. Pasion listed theirs at one point as 4T and looking at the RPM specs for both at 48V I think they must be 4T. I don’t plan to push more than 2000W out of them but wanted an oversized direct drive hub for hill climbing power. Nothing feels as smooth as a DD hub if you like pedalling because the two systems are separate (not to mention more reliable). No gear whine or clicking chain. Tried out a friend’s trike with a BBSHD and mid drives take a lot of coordination and effort to use: no pedalling during shifting, switching assist modes, noisy, less smooth.

Not a bad idea with the stem but since this is a proprietary hard to find stem that mounts directly on this fork I don’t want to make it irreversible. Would do it with a regular stem setup though.

Guess I better order the shims off Aliexpress and wait another two weeks lol.

ben2401   1 mW

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Re: DIY handlebar shim ideas? Using 22.2mm Moto-x bars (same diameter as BMX) in my 31.8mm stem

Post by ben2401 » Apr 02 2021 11:09pm

MoneyPit wrote:
Apr 02 2021 8:20pm
Shims are cheap, and they have features like horizontal ribbing that uniquely suit them to their job on a mission-critical part. If the bars slip you could be up for new teeth at worst or just constantly pissed off that every time you grab the bars hard they move. Or spend like $6 on eBay. Thats where I get mine.

Worth mentioning is I've been there and done that. I used some alloy tubing that I sawed in half. Without that ribbing you can clamp the bejesus out of the bars all you want and they'll still move.

If you are committed to DIY for the sake of adventure... weld it into the stem.
Good to know, probably going to order some shims then, unless I get lucky at the local bike shops this weekend.

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Re: DIY handlebar shim ideas? Using 22.2mm Moto-x bars (same diameter as BMX) in my 31.8mm stem

Post by LewTwo » Apr 02 2021 11:35pm

ben2401 wrote:
Apr 02 2021 8:12pm
Not a bad idea if I can’t find/make a shim that fits. You think fibreglass will be hard enough to get a good grip from the stem? Can it handle being cranked down on without cracking?
The shims are likely a better idea if you can find them but regarding strength: I run carbonfiber handlebars that were intended for mountain bikes. I have seen fiberglass ones as well.
The more I learn the more obvious the immensity of my ignorance becomes.
Weight Wennie E-Bike https://endless-sphere.com/forums/viewt ... 3#p1173723
Shaft Drive Grocery Getter https://endless-sphere.com/forums/viewt ... =6&t=90718
...and thanks to Justin!

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Re: DIY handlebar shim ideas? Using 22.2mm Moto-x bars (same diameter as BMX) in my 31.8mm stem

Post by dogman dan » Apr 03 2021 6:13am

All you need is some scrap aluminum or steel sheet that is fairly thick, like 1 mm or so. That may be a bit of a scrounge to find, if you can't find what you need at the first couple bike shops. Might be sheet the right thickness in a hardware store, but more likely too thick there, 1/8 stuff. Consider oddball ideas too, like cutting a seat post section into a shim, or something like that. Common chain link fence top rail, electric conduit, old swimming pool skimmer pole, flag pole, anything might be just right cut to length and sawn into a two piece shim.

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