Is my GMAC supposed to sound like this?

[PedalUma]

The guy came pick up his gravel bike so we took his and another on a 5 mile mostly gravel test ride with some fast flats and some hills. He is grinning like a little kid. I lived in So Cal for a while when the brick downtown was flattened. I was selling electronics at the time and all the CRT TVs went off the shelves and onto their faces. Now I am onto a Surly 12-sp Bikepacking conversion with two batteries. Thanks for the complement @tomjasz! You are right about gloves for the palms and knuckles. Speaking of high bars. There was this club with high bar stools. One guy's pickup line was, Can I push in your stool?

 

[Edrummer]

The guy came pick up his gravel bike so we took his and another on a 5 mile mostly gravel test ride with some fast flats and some hills. He is grinning like a little kid. I lived in So Cal for a while when the brick downtown was flattened. I was selling electronics at the time and all the CRT TVs went off the shelves and onto their faces. Now I am onto a Surly 12-sp Bikepacking conversion with two batteries. Thanks for the complement @tomjasz! You are right about gloves for the palms and knuckles. Speaking of high bars. There was this club with high bar stools. One guy's pickup line was, Can I push in your stool?

Which Surly frame are you using? Motor,batteries, voltage?

 

[davelien]

Just putting it out there. Sometimes you need a spacer between the cassette or freewheel and the hub. Could something be in there rubbing? That does not sound right. I am thinking this because it is not on the brake side.

I took the cassette off, same noise. I'll send it back to Grin, again. Thanks for the suggestion.

 

[PedalUma]

I'll send it back to Grin, again.

Surly frame

That is a bummer. Would have been cool if that was it. By the way, It takes effort to make a joke! At least I tried with the pickup line joke. @Edrummer, here is that bike in its current state. Thanks for asking. I only just started. REI had way overtightened thin zip ties to hold the shift housing crimping it in six places. I am doing that first with new housing and a premium tandem shift cable. I will use a small mid-drive like that other Red Gravel bike, a medium sized battery and a small one both at 36V with high-end cells and BMS. I will unlock the motor to hit peeks of 700W but with a low nominal rate of bleed-out at 350. And I will chop off all connectors and solder for a cleaner build.

 

[JES2020]

I took the cassette off, same noise. I'll send it back to Grin, again. Thanks for the suggestion.

I would request a new one this time !

 

[linklemming]

I recorded another short video just now, I think it more clearly demonstrates the noise. Especially off throttle when the RPM is coming down, the same noise no matter what. I reached out to linklemming, my guess is that he will confirm that his Gmac sounds nothing like this. I'll push back on Grin.

My GMAC sounds exactly like this latest video. I dont notice any such sounds while riding unless I am putting alot of power thru it.

GMAC is a nice upgrade for a CCX, I have been looking at a new ebike project and havent used my CCX in awhile

 

[tomjasz]

My GMAC sounds exactly like this latest video. I dont notice any such sounds while riding unless I am putting alot of power thru it.

GMAC is a nice upgrade for a CCX, I have been looking at a new ebike project and havent used my CCX in awhile

Thanks Gary!

 

[tomjasz]

I would request a new one this time !

Even if you haven't a clue as to what the sounds might be?

 

[PedalUma]

If they say this is normal and you find it unacceptable, go in a different direction. I think it is not acceptable. It sounds sick, in the bad way.

 

[tomjasz]

If they say this is normal and you find it unacceptable, go in a different direction. I think it is not acceptable. It sounds sick, in the bad way.

I guess I’m more trusting of Grin. Of all the orders I’ve made and kits I’ve sold I suspect user error. YMMV.

 

[JES2020]

If they say this is normal and you find it unacceptable, go in a different direction. I think it is not acceptable. It sounds sick, in the bad way.

Also, if your wheel is supposed to wobble like that, I would go another direction.
The sound is one thing but the wobble is another.
Personally, one reason I chose a IGH, was because they are quiet.

 

[linklemming]

Here is video footage of mine, perfectly normal GMAC with 4k miles. The noise is much higher in this video than in real life. I would say the noise is comparable to my stock CCX under the same conditions.

The motor is effectively silent (over road/wind noise) under 500watts. I cant really even hear it at top speed (36mph) due all the road/wind noise. I notice the noise most when climbing at slower speeds. Even then its NOTHING like in the video

FWIW, I am SUPER finicky about noise. Noisy ebikes have no place in my stable.

 

[JES2020]

Here is video footage of mine, perfectly normal GMAC with 4k miles. The noise is much higher in this video than in real life. I would say the noise is comparable to my stock CCX under the same conditions.

The motor is effectively silent (over road/wind noise) under 500watts. I cant really even hear it at top speed (36mph) due all the road/wind noise. I notice the noise most when climbing at slower speeds. Even then its NOTHING like in the video

FWIW, I am SUPER finicky about noise. Noisy ebikes have no place in my stable.

THAT, sounds and looks perfectly normal.

 

[tomjasz]

I took the cassette off, same noise. I'll send it back to Grin, again. Thanks for the suggestion.

@davelien Any feedback or updates?

 

[davelien]

Any feedback or updates?

@tomjasz I've shipped the wheel assembly back to Grin. They should have it before the end of the week. I've made it clear what I expect. My fingers are crossed.

 

[Pine_marten]

@tomjasz, OMG, me too! Just a little spacer, 1/2 mm thick solves the problem.
Totally off topic, I stayed up until midnight making this bike electric. It is a Black Mountain frame, handmade in Point Reyes, California. That is an amazing place to ride. I am taking the gravel bike out right now.
Take a look for two minutes here:

All that gravel and all that bare skin. Once you've had the doc scraping it out with a scalpel you never forget it.

 

[Pine_marten]

Do you have a load of sealant in that tire?

 

[davelien]

OP here, an update. Based on a recommendation from Peter at Grin I had him switch me from the GMAC to a Nine Continent RH 212. I have to say that it is the perfect motor for me, it's basically silent and has plenty of power for the hills I ride. (Grin's motor calculator shows them to be 'fairly equal' in performance.) So, my Juiced CCX is now, finally, the bike that I wished it was from the beginning. Now, less worrying about niggling issues and more time riding!

 

[tomjasz]

OP here, an update. Based on a recommendation from Peter at Grin I had him switch me from the GMAC to a Nine Continent RH 212. I have to say that it is the perfect motor for me, it's basically silent and has plenty of power for the hills I ride. (Grin's motor calculator shows them to be 'fairly equal' in performance.) So, my Juiced CCX is now, finally, the bike that I wished it was from the beginning. Now, less worrying about niggling issues and more time riding!

I recently purchased the same 9-C motor. It’s really quite powerful and runs like a champ. I’m glad to read you now have the bike you want!

 

[linklemming]

Thanks for the update. I have been considering the RH 212 as well. As you mention they seem to be fairly close in the motor simulator athough adding 6# is alot, Im about 1 beer away from ordering one