Reebok GB40s Pedal Resistance Slipping

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WH40kgeek
Posts: 2
Joined: 6 Dec 2021, 6:33pm

Reebok GB40s Pedal Resistance Slipping

Post by WH40kgeek »

Hi Guys,

I've had this Reebok OneGB40s for about 8 months now. I use it quite alot, sometimes 3-4 hours a day.

It works perfectly and hasn't missed a beat until just recently.

I turn it on, start a manual programme, set the resistance to the level I want and pedal away as normal but now randomly the pedals will lose ALL resistence for just one or two seconds then resistence comes back and it carries on like nothing has happened.

I will do this completely randomly during a ride, sometimes several times and it doesn't matter if I just started or nearing the end. It never lasts for more than one to two seconds.

I've had the side panel off, the belt is 100% OK and fitted correctly, it is tight and there is no obvious sign of anything amiss. The flywheel and magnets are also fine, nothing loose or broken and the magnets move about as they should depending on the resistence level you select.

Bike makes no audible noises or anything to suggest something may be wrong either. A real head scratcher as to what may be causing it.

No luck with contacting Reebok Support either, get no response from them.

Any help appreciated.

Thanks!
cyclop
Posts: 961
Joined: 3 Oct 2013, 7:49am
Location: Dumfriesshire

Re: Reebok GB40s Pedal Resistance Slipping

Post by cyclop »

When you say belt,I,m assuming a smooth drive belt rather than a notched,Gates type belt.I would be looking at the belt-wheel interface.Is the belt or drivewheel polished from use?If so ,try roughening up with a medium fine sandpaper,enough to dull the polish. It sounds like you,ve used this machine much more than an average user might,almost like a gym based machine,am I correct?
WH40kgeek
Posts: 2
Joined: 6 Dec 2021, 6:33pm

Re: Reebok GB40s Pedal Resistance Slipping

Post by WH40kgeek »

Yeah, I've used it ALOT more than its 350 quid price tag probably assumes it would be used and at a resonable speed avg 250w-300w over an hours ride, sometimes 4 hours a day.

The resistance is driven by a pretty sturdy strip of magnets near the flywheel and there isn't any visable wear on the magnets or flywheel and no spall or dust/residue to suggest wear on either of these so I think we can rule this out.

The belt is a ribbed belt (VEGA X PJ10116/400J), the underside is ribbed and smooth on the top, the cog attached to the flywheel is also ribbed so it fits in snug and can't slip out or fall off BUT you may be 100% right with it still being worn/wearing or smoothed out just enough on the ribs for it to start slipping intermitently while pedaling.

Thanks alot for the advice. I'll try giving it a sanding, rough the underside and see if it improves or worsens it :)
offroader
Posts: 114
Joined: 18 Dec 2018, 4:47pm

Re: Reebok GB40s Pedal Resistance Slipping

Post by offroader »

My old Polar(?) unit had a fairly rubbish bottom bracket/freewheel combo thing made of plastic.
When this failed it started with slippage very similar to what you describe. Eventually it failed completely during a spirited session and resulted in me joining the very select gang of people who have crashed a stationary exercise bike!

I fixed mine by filling the bb cartridge with epoxy resin. If yours is 8 months old I suspect a replacement under guarantee would be more appropriate
iandusud
Posts: 1577
Joined: 26 Mar 2018, 1:35pm

Re: Reebok GB40s Pedal Resistance Slipping

Post by iandusud »

Even if your belt is properly tensioned and visually in good condition it doesn't mean that it won't slip, and once it starts it will only get worse. You can get aerosol sprays to treat this but IMO a new belt is the best solution. I imagine that if you buy one from Reebok it will be very expensive but if you measure your one up you will be able to buy a replacement from a specialist supplier at reasonable cost. Simplybearings.co.uk would be a good place to start.
cyclop
Posts: 961
Joined: 3 Oct 2013, 7:49am
Location: Dumfriesshire

Re: Reebok GB40s Pedal Resistance Slipping

Post by cyclop »

Out of interest,does it slip(if that is what it is)from the word go.If not,might this further confirm a belt problem which must warm up and therefore soften/expand slightly .Of course,if it does "slip" from the off,this doesn,t mean it,s not the belt.Is there a belt tensioner device?Also,I doubt a machine of this quality was designed for the "beasting" you give it!
oldman2023
Posts: 1
Joined: 27 Jun 2023, 1:48pm

Re: Reebok GB40s Pedal Resistance Slipping

Post by oldman2023 »

I know this is an old post and probably not much help to the original poster but may help someone else.

I have a Reebok GB50 and thought the belt was slipping, occasionally the resistance would vanish and then come back.
Sometimes there was a crunching sound before the loss of resistance.

Eventually a year or two after it started it lost all resistance so I took it apart so I could tension the belt.
I pulled the flywheel back as far as it would go bit it made no difference the next thing I tried was to replace the tension spring with one four times stronger and again no difference.

After hours of searching for a replacement belt online without any luck I gave up, I put the bike in the garage but gave it one last look that's when I noticed that it wasn't the belt slipping but the rear pulley, it was turning with the belt but the flywheel wasn't moving.
I took the flywheel out and removed the bearings and in the middle of the flywheel was a worn out needle bearing.
The crunching sound was the cage of the bearing disintegrating over time.
I measured the size and tried to find one online and did find one for a few pounds, however it made no sense as a bearing won't make it grip the wheel and then I found what was called a clutch bearing.
A clutch bearing grips in one direction only just like the sprocket on an chain bike.

This bearing is more expensive £18 but after installing the new bearing and putting it all back together it fixed my slipping belt issue.
I also put the belt back to how it was originally with the original spring and it seems perfect now.

How long it will last is another matter and it's not the easiest fix to do.

I don't know if other bikes other than the Reebok GB50 yous a clutch bearing as I couldn't find any info online so just thought I'd put the info somewhere.
cyclop
Posts: 961
Joined: 3 Oct 2013, 7:49am
Location: Dumfriesshire

Re: Reebok GB40s Pedal Resistance Slipping

Post by cyclop »

Chapeau !I think I,ll start a new thread on difficult to diagnose problems. :roll: :?: :idea:
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