2020 Fathom Pro e-1: OEM Harmonics issue solved

Doacharlie

New Member
Aug 13, 2020
4
1
Calgary
Happy with the HT, but only after a lengthy shop visit. Purchased at a local shop after a decent experience on a short test ride. When I got the bike home and took it out on a longer, quicker ride, i noticed quite a loud harmonic sound (anything north of about 75% of my max speed) while on flat pavement. Was so noticeable the guys riding with me chuckled a little.
Brought the bike back and the service guys went to work. They took it for a test drive and confirmed what I was hearing; almost like a drummer tapping a cymbal. They tried everything; took one brake off, then took both off, check spokes, hubs, you name it. Problem was solved once both OEM rotors were taken off. They re-fitted the bike with upgraded Shimano’s RT86 (ice) and things were silent. While they were working on my bike, I took the two identical Fathoms they had on the shop for a spin....both exhibited the same sounds. It’s a shame Giant cut corners with low end ($23) components. I think the OEM rotors would be fine on a non-e-bike where getting to upper speed, and maintaining the speed, requires more effort.
 
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Chris G2

Member
Jan 26, 2019
5
1
South Wales
I got the same on my fathom e+2 after 15mph, didnt have a clue what it was. Will this be covered by warranty, I’ve had the bike 3 weeks
 

aaronplant

Member
Jul 26, 2020
20
6
Derbyshire
Definitely had this problem too. Thought it was spokes, they all seemed ok. Nice to know what is causing it - thanks! I get this between 10-15mph. The bike is going into Rutland Cycles for it’s 6 week check soon, so I’ll mention it to them and see if they can do anything :)
 

Tmeyer37

New Member
Jun 22, 2020
67
33
Fremont, CA
I get the same noise from my front brakes around 15 mph. Doesn't do it on the rear though. Been wanting to have my lbs look at it but they are so booked up I dont want to be without my bike for more than a day. First world problems.....
 

Davemtb

Member
Jul 12, 2020
27
14
Australia
Giant Fathom E+2 Pro - yep, same problem. I've fiddled with caliper alignment for ages, mainly the rear. Problem lessens with wear! After a few brake pad changes and 8000km later my rotors are worn and I'm about to upgrade to the Shimano’s RT86. I agree - the stock rotors are crap and easily warp slightly.
 

DaveMatthews

Well-known member
Aug 12, 2018
477
323
Vancouver, B.C. Canada
Giant Fathom E+2 Pro - yep, same problem. I've fiddled with caliper alignment for ages, mainly the rear. Problem lessens with wear! After a few brake pad changes and 8000km later my rotors are worn and I'm about to upgrade to the Shimano’s RT86. I agree - the stock rotors are crap and easily warp slightly.
Is the RT86 a direct fit/drop in replacement?
 

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