R&M SD Belt keeps coming off

[Peve3]

Hi all, I have had my SuperDelite for about a year and its been working fine but recently the belt system keeps coming off at the rear. I have a Rohloff geared hub installed, I initially noticed the belt would pop off when cycling up steep hills so im guessing high torque going through the components but recently its been getting a lot worse. The recent cold conditions have meant the belt came off almost every time i went around a corner (was about -5 DegC) My initial thoughts are to tighten the belt but i cannot see how this is possible, as the rear wheel is fixed and cannot slide back. I also checked the retaining spring and that seems very tight still. So my last area of investigation was along the lines of needing a new belt, as it could have become loose, but that doesn't explain why it comes of far more frequently in cold weather. Surely that would keep more tension on the belt ?

Any advise would be greatly appreciated.

 

[Kentish Man]

Didn't realise this could be a problem. Is it a simple job to put the belt back on to be able to continue your journey?

 

[Peve3]

It usually comes off the rear teeth, so i grab the top part of the belt whilst standing to the rear of my bike and pull it towards me whilst pulling it to one side. This gets it back in-line without having the take the rear wheel off. Not really a viable long term solution....

 

[Jay Kay]

Be careful not to twist the belt as it can damage the carbon fibres leading to belt failure. There is a warning about this in the belt manual. It sounds like belt tension, or maybe the snubber wheel near the rear hub needs sdjusting?

 

[Peve3]

Thanks for the tip, I’ll make sure not to twist it. But how would one go about tensioning the belt ?

 

[PedalUma]

With the full suspension this Gates Carbon Drive has its own automatic tensioner behind the chainring(beltring). It sounds like it is time to order a new belt. These same belts are used for automotive so you might just remove it and take it to an auto parts store where they can take its measure and sell you a replacement. Someone may have rested their foot on it or it got bumped. One of these bikes will join our group ride this week. Here is the 80Nm bike I will be riding along side the SuperDelite. It is 20.20 kilos and is a three-speed with a coaster brake. His version has two batteries.

 

[indianajo]

When toothed belts start doing that in factories, they usually are warped. Same Gates technology, higher power. Could be pulleys out of line, could be takeup wheel is tilted. Use a laser level if your eyesight is not good enough to spot misalignment. If those are not wrong, buy a new belt.
Saved a lot of chain maintenance, didn't you? My first chain only lasted 2 1/2 years & 5000 miles.

 

[Mike TowpathTraveler]

If you've already rolled the belt on, according to Gates, this belt needs to be replaced. Here's the Gates Service Manual to get you going. Note the Gates tension guage, a "Kricket" guage. Worth the investment. Link: https://www.r-m.de/media/filer_public/80/6b/806bb209-a6aa-4f13-8eb7-d9d491f79f6f/belt_gates.pdf

I have a 2013 Trek Soho DLX with the Gates Carbon Drive. Tension is done by manual adjustments, back and forth, on that rear drive axle. I believe on your R&M that tension is created on the belt with a tension pulley. I would look at that tension pulley as the culprit in throwing your belt.

By the by, the Carbon Drive Belts are exclusive to bicycles with the Gates drive system. On the newer belts and pulleys, there is a center groove in the belts where the raised center groove on the front and rear pulleys can help keep this belt aligned on the pulley better than the earlier designs. No local automotive parts supply is going to have a clue in how to help you. Your R&M dealer, though, will. And they might be the ones to have a look at that tensioner pulley as that will be an exclusive R&M part. Good luck!

 

[Bronte]

I put 7400 km on my 2020 Superdelite Rohloff last year and towards the end of the season I was also experiencing the belt "slipping" while going up hills. It was easy enough to put the belt back on as you have found; however, based on a discussion with my bike shop and referring to the Gates Technical Manual, the most likely cause is low belt tension. Specifically the Manual says "Lack of belt tension can lead to tooth jump when the teeth of the belt slide over the teeth of the rear sprocket". For the internally geared hubs, the tension needs to be 28 to 40 lb ("tension recommendations are a good starting point which may need to be adjusted higher or lower based on rider size, gear ratio, and power placed on pedals"). The tension is adjustable on the Superdelite although I have yet to do it. I have measured the belt tension on my bike and it is below the recommended tension hence the skipping belt. Before I start biking this season, I will certainly be adjusting the belt tension. Given the power of the Superdelite, I will be trying for the higher tension recommended by Gates. I have inspected the front and rear sprockets along with the belt and they do not appear to be worn based on the Gates information. My bike shop suggested that I should get at least 10,000 km from the belt (although riding in wet muddy conditions can cause the belt to wear faster).

 

[PedalUma]

I see it! There is a center groove. Thanks.

 

[Mike TowpathTraveler]

Bronte: Please elaborate how the belt tension is set on your R&M. Looking at the link here https://ebike-mtb.com/en/riese-muller-delite-mountain-supercharger-2-2020-unveiled/, I see a tensioner pulley by the front chain ring. While back at the rear sprocket, there is a pulley in place that serves to keep the belt in contact with the rear sprocket.

That tensioner is what I believe sets the pre-load tension on the drive belt.

Compare that to the Supercharger shown near the end of the article. Note that the Supercharger has an adjustable rear dropout that sets the belt tension by moving the axle assembly fore and aft. This is how my old Trek Soho belt drive has it's tension set.

That tensioner pulley is no different than what you'll find in a belt driven overhead cam automobile engine. And with cars, if that tensioner comes out of adjustment, the rubber belt skips teeth....with catastrophic results.

The Gates manual I linked does not appear to have info on that tensioner pulley, which I believe is an R&M proprietary component. It makes sense if the tension is not what it should be, then the belt will skip. But within the Gates manual I linked, they are pretty adamant that the belt cannot be rolled or pried back onto the pulleys as damage to the belt cords will result.

 

[Alaskan]

Not sure about the Superdelite but my Homage which has a similar swing arm, has adjustable dropouts where you loosen the bolts that hold keep the dropouts in place so that it can be pushed and slid back using the adjustment screws. Those tentioning screw are accessible inside each of the dropouts at the bottom back end of the swing arm. Either use the Cricket tool or get the app that listens to the tone of the belt when you strum it to gauge the tension. Make sure you snug the bolts that secure the dropout after you get the tension right.

 

[Alaskan]

By the way what people are calling "the tensioner" is there to take up the slack when the swing arm moves up and down. It is not used to set the belt tension while the bike is at rest.

 

[Bronte]

Mike - there are two large screws on either side of the rear frame where the wheel is attached (yellow arrow in picture). These need to be loosened to make the adjustment. The red arrow shows where the adjustment screw is located on either side of the frame (seen from the back). This will move the axel assembly as you indicated in your comment.

 

[marcparnes]

Make certain you adjust each side of the axle the same amount in order to maintain the original wheel/sprocket alignment.

Marc

 

[JVBulman]

Adding to others' suggestion of checking the belt tension - double check the lockring on the Rohloff. We've seen an alarming number of them work themselves loose and have had a number of Rohloff/Vario R&Ms suffer belt-drop from the rear cog not being securely held in perfect alignment with the chainring.

 

[Mike TowpathTraveler]

Bronte: Thanks for that clarification! Been trying to find specific instructions on setting belt tension for the Super Delite on the net, but it's just not out there. Chris Nolte of Propel does a nice video on the Gates Carbon Drive that's worth a watch here.

 

[Bronte]

Mike - I have also been looking for specific instructions with no luck but I did find a YouTube video showing the process on a different bike. My bike shop indicated that you need a T40 torx wrench for the screws on either side of the frame and they need to be tightened to 15 Nm torque when the tension adjustment is complete. The tension adjuster on either side is 4 mm allen key (I think). You need to be sure that the same adjustment is made on both sides as mentioned by Marc in order to maintain proper alignment of the belt and brakes. I hope that Chris (Propel) will do a video on making tension adjustments (I suggested that in a comment for his introduction to e-bike maintenance).

 

[Bronte]

Adjusting the tension on the belt was very easy. Tools needed: torx T40, 3mm Allen key and gates krikit tension gauge (I purchased the “v-belt“ version on Amazon which is much cheaper than the one for the non v belt). First step measure the current belt tension (target tension is 28-40 lb). Second step is to loosen the 4 torx screws (2 each side of the rear frame). Third step is to adjust the tension using the 3mm Allen key —adjust counter clockwise to increase tension or clockwise to decrease tension There are 2 tension adjusting screws one on each side (red arrow in my earlier post). Be sure to make the same adjustment on both sides (this ensures the belt is aligned correctly). Check the belt tension in the middle of the belt on the top (half way point). Check the belt tension in 4 places (1/4 turns).. Once you achieve the correct tension, re-tighten the 4 torx screws to 15 Nm torque. I adjust my belt tension to 40lb and did not experience any belt skipping since I made the adjustment.

 

[gtpharr]

I find it interesting that Gates recommends 28-40 lb belt tension, but their Kriket Gauge Tension meter has a scale range of 40-150 lbs. I don't think I would pay $40 or more for a gauge that will not read in the scale I need.

Wonder if anyone has tried using the free mobile app on their phone?