Gates drive tension -- any rule of thumb methods?

When I first got mine, I put my spoke tension meter on it and IIRC got a number of 13. Units are irrelevant because there's no Gates belt drive entry on the conversion chart. I assumed that the shop would have set it up something like, maybe I'm wrong. I try and aim for that if ever I have to re-tension, but I don't ever check it between wheel removals.

Anyway, that's too slack to create a tone if it's plucked, so the app doesn't work for me either. It's been 100% reliable in the year I've had it and has probably done 3000 miles in that time, (commute bike) I assume it would be causing problems by now if I was horribly wrong. Alignment is much more critical I think, the BB wasn't quite seated fully home when I first got it, and it made some odd noise until tightened up properly.

It moves about +/- 1cm if I wiggle it up and down in the middle of the run between chainring and sprocket.

Thanks, yes, I was thinking the alignment is more important. I think I'm well under 1mm off, so hopefully good there.

For minimum tension, I assumed that the sprocket size would be relevant -- but that doesn't seem to be a parameter in the Gates recommendations. Mines 46/28, relatively large, so guessing a lower tension may be OK...

I may buy a spoke tension meter as well -- much cheaper than a Gates tool and perhaps enough

I may buy a spoke tension meter as well

So, you'll be able to be repeatable,  but how are you going to decide the first time? Can you get someone to load up the app for you for the initial set-up then measure it with the tension meter?

Honestly,  I'd not sweat it too much. Just make it not bow-string tight and you'll be golden.

is there not something about twisting it and being able to twist it 90 degrees is the right tension or have I imagined that?  Might be worth looking into?  Don't take my word for it tho please

Never heard of twist technique and the one thing you absolutely don’t want to do is bend or twist a gates belt.  Hence why you never roll the belt on by turning cranks like you would a chain. They just don’t deal with any sideways flex. I’ve snapped one belt in my short ownership.

Btw the gates app measures the tension in hertz I think.  And for mtb 50-70 is the range iirc. So would a guitar tuner or similar measure and give frequency too? It’s an audible reading the app is taking.

that is more flex than you’d have in a SS chain. I’d say the +/1cm at the belt mid point isn’t far off for a rule of thumb.  No looser and you’d get away with a bit tighter.

@tjagain

Thats how you used to timing belts.

Id say your over thinking it. Its toothed so its not going to slip.  So leave some slack in it.

So, you’ll be able to be repeatable, but how are you going to decide the first time? Can you get someone to load up the app for you for the initial set-up then measure it with the tension meter?

Honestly, I’d not sweat it too much. Just make it not bow-string tight and you’ll be golden.

Yea, I think I can get my partner to download the app to get it set up first, so I could feasibly calibrate a spoke tension meter (which I should prob buy anyway)

I'm not too worried about it, but I'd like to not overtighten and end up wearing out my bearings prematurely

And yes tj, I had heard a rumour about a twisting method, but via a friend who I think got that advice from Halfords, so I was a little skeptical!

bri-72, that's an interesting idea, I have a bunch of musician friends...

I use the tension app but it normally takes a few goes and sometimes I get wildly different averages so the average of 3 needs a lot of goes, normally my finger starts to hurt after a few!  I think my spokes tend to ping at the same time which confuses the app.  Also, as is often the case, my cranks or pulley isn't perfectly round so the post and tightest point is quite different on the app

As mentioned, belt alignment is important. I thought I could eyeball it but as the belt doesn't have links I couldn't see if it was straight. Ended up googling it and using a ruler/Vernier calipers to find the centre of the frame and rear hub and then measured to the pulleys.  Had to move the back cog quite a bit.

Do the job properly or regret it. Too often people complain that they purchased product X because it is industry standard or market leader and complain of poor performance or it failed within warranty. Often the investigation reveals that a work around of the recommended installation method was used, but by that time the disgruntled owner has likely started an internet thread condemning the product and announcing a waste of money. Hardly fair on the company. I'm not implying that you would do this, but I have a Gates myself and find they don't react well to not being set up well.

Rereading your first post, slack is definitely not the way to go, although I've also seen the video you mention.  It should be under tension with no visible slack, you should be able to ping the belt and get a note out of it.  You must have a mate that's happy to put the Gates App on their phone for an hour 🙂

Thanks all,

spooky, there's def no visible slack. I loosened off the slider bolts by about 3/4 of a turn as it seemed very tight (like, cranks only spinning 1/2 a revolution even when I gave than a hard push; BB is fine). The cranks feel a little freer now (still less so than my chain-drive single speed), but the belt still 'feels' tight to hand. I def couldn't twist it to 90 degrees without some effort (which I know I should not do). Nonetheless I will try to get my partner to check with her phone

As for alignment, I did that with a long metal ruler, which is one of the methods Gates suggest -- I have sufficiently thin cassette spacers that I was able to get it within a fraction of a mm

lotto: I def don't want to be one of those people... I read a lot about belt drive before getting this, and was amazed how many on here for example cite MidlandTrailquestsGraham's experience, despite the fact that he seems to break everything! I do think his experience is def useful feedback, but not a justification for disregarding belts

I ran Gates for 5 years or so, and settled on this method:

• Set it as tight as seemed 'correct' (probably based on a lifetime of gauging singlespeed chain tension by feel)

• Loosen it off by 2 or 3 'clicks' from there - so that it felt a bit looser than you might expect but not completely floppy - 'click' is entirely subjective unit of measure so this method is not scientific.

(I got rid of the belt drive first, then I got rid of the Rohloff and now I am happy...)

First ride today, plenty of single speed gurning but zero skipping, so all good

Damn these things are quiet...

I bought some kind of tool when I had mine I can't remember what the hell it was, ill have a look over the weekend to see if I can find it if I can you can have it

@firestarter, that's a very kind offer 🙂 happy to give you some cash if it'll do the job

I'll have a good look on Saturday mate I'd I can find it it's yours mate

Absolutely DONT do the twist test unless you want to significantly reduce rhe belt life and have it snap in a totally PITA location. It breaks the carbon strands (the carbon part of the carbon drove !)

The tooth count on the ring and sprocket are pretty irrelevant.  As pr others the alignment is important.

(I find the twanging and using rhe Gates app to be hopeless on my gravel bike - doesn't register half the time, and the other half the time the results are utterly random and all over the place.

Ended up stumping up the ££ for a proper gauge (the Euro one that hangs  a weight off the belt and has a deflection gauge to determine the tension )

All I can say is that 'by hand' it's not as tight as one would probably expect it to be when actually correctly tensioned.

Absolutely DONT do the twist test unless you want to significantly reduce rhe belt life and have it snap in a totally PITA location. It breaks the carbon strands (the carbon part of the carbon drove !)

Yea, I did think this was a strange test. I did very gently twist it and it only gets to 45 deg max. Twisting anymore felt a very bad idea

I've heard similar about the Gates app as well