I had the same aggravating problem and it turned out to be caused by burrs on the teeth of one of the chainrings. Feel each tooth for burrs and use a file to grind them off. I opt for steel chainrings when I can now because of this.
On Monday, March 3, 2025 at 3:24:45 PM UTC-8 iamkeith wrote: > > I agree with everything Bill L. said, above. Normally I'd add that this > isn't a model-specific issue but, in this case, the fact that it's a Clem > makes it a little more interesting. But in the opposite way... in that I > would have thought these problems more rare. > > I have a 59cm Clem H, and it’s the only bike I've ever had that I will > regularly and INTENTIONALLY cross-chain (big/big or small/small > chainring/cog combinations). The chainstays are so long that the chain is > not angled or flexed very severely when I do. > > I also have mine set up as 2×9, with 24/38 & 12-34 and friction shifters. > Simple chainrings with no ramps. Long-cage rear derailleur to take up lots > of chain slack. Shimano CX-70 front derailleur, so the cage shape follows > those smaller chainrings pretty well. I don't have any trouble at all but, > as Bill suggests, I rarely if ever shift the front under load because of > habits learned by cutting my teeth before indexing and shift aids existed. > > Other things worth considering, based on my own satisfactory experience: > > Too much chain slack can sometimes precipitate chain drop because it > bounces off. This could be exacerbated by the long stays / extra-long > chain. Make sure you have as few links as you can get away with, measured > in the big/big combo. > > Chainline should be less critical than most bikes, but maybe I got lucky > and found an ideal one. I can measure if you want to experiment with bb > spindle lengths. > > Obviously, the limit screws need to be adjusted properly but, maybe try > setting them by finding the position where you CAN'T shift to the next > chainring, and then going just a nudge beyond that. > > How far are the two chainrings separated laterally? Sometimes too narrow > of a spacer on the inner chainring can cause the chain to drop past it > instead on onto it. Conversely, too thick can cause the chain to get stuck > between them. > > On Monday, March 3, 2025 at 11:35:29 AM UTC-7 Bill S wrote: > >> Bill and John, >> >> Appreciate both of your thoughts and suggestions! We will of-course touch >> up the frame so it doesn't rust in the future, but yes- pretty gnarled. >> >> Cassette is a 9 speed 11-34t. Converting to a one-by setup is certainly >> an option, and maybe I'll go that route if it comes to it. We're in >> Pennsylvania, so most rides end up with some steep hills where it is nice >> to have the wider range. I would put on a larger rear cassette if I went >> that route. >> >> I do really like Bill's #3 suggestion above, regarding the alignment of >> each ring, and will give that a go to see if that helps. >> >> It could definitely be operator error as well, which we did talk about. >> She's been riding a lot the last 4 years or so on a 98 bianchi volpe which >> we set up with bar end friction shifting - so she isn't new to shifting by >> any means. It has a triple up-front and she never had any issue with that, >> but the 2x could be a different animal which takes a bit more thought since >> its a larger jump between the rings. If we're out together on the weekend >> we'll typically end up doing around 40-50 miles on varied terrain. I will >> try and take the bike out myself later today, and see if I have any issue. >> The chain-suck was just happening so often that it seems like there might >> be something I was missing/figured it was worth asking to see if anyone >> else had the same happen with a 24/38 since I know that is an option Riv >> has on thier completes. >> >> On Monday, March 3, 2025 at 12:03:52 PM UTC-5 John Williams wrote: >> >>> Hello Bill & Bill! >>> >>> YIKES! So sorry about the frame scrapage! That hurts to look at! DARN! >>> >>> I agree with Bill L on his well versed knowledge. >>> May I add my two cents? >>> I cannot tell from the bike photo what cassette ring count is on the >>> Clem. Is it a 9 speed? 10? More? >>> A narrow chain for a 10 speed may not play well with the rings on the >>> Silver crank. >>> Back in the 80's & 90's, triple MTB cranks with "granny" rings were >>> popular and the dastardly chain suck was common. >>> Mistake #1 was shifting into it by accident. We had rigid forks and >>> sometimes, overshifting happened on a sudden jarring bump. >>> The tiny inner ring really didn't interface all that well and sure >>> enough, the frame/chain jam would happen. >>> My simple suggestion is to turn the low limit screw on the front mech to >>> not allow left hand shifting to the small ring. >>> (Agreeing with Bill L., operator error) Have your spouse only shift with >>> her right hand. >>> I would change the chain to accommodate the rear cassette and the front >>> rings, and learn for the time being to only shift in the rear. >>> If your uphill grades are steep, possibly a wider range rear cassette is >>> in order. If the terrain is not steep, the 38 will get her everywhere. >>> Chalk up another win for 1x systems. Simplify, whenever possible. That >>> bare steel will need some TLC. >>> Happy Trails, >>> JohnRobertWilliams >>> Traverse City, MI >>> >>> >>> >>> On Mon, Mar 3, 2025 at 10:27 AM Bill Lindsay <tape...@gmail.com> wrote: >>> >>>> I have three thoughts on the matter. Maybe four...maybe 5. Some, or >>>> all, maybe don't apply to your situation. >>>> >>>> 1. The first photo has the chain sucked all the way around to the top >>>> of the cranks, and my brain goes to "why did they keep pedaling that >>>> long?". It's like when you are driving on a mountain road, overshoot the >>>> corner and are now in the gravel, and you keep your foot on the >>>> accelerator >>>> for one second...two seconds, and keep driving off the cliff. Try to hear >>>> and feel it happening and stop. Don't drive through the gravel and off >>>> the >>>> cliff >>>> >>>> 2. Chain suck is always much worse when you shift the front under load >>>> at low RPMs. When I taught new riders how to shift the front, I told them >>>> the front shift should be dictated by the terrain, and should therefore be >>>> obvious and easy to see and easy to anticipate. The rear is for "feel". >>>> On a 24/38 in front, the 24 is for pedaling up steep inclines. The 38 is >>>> for everything else. The classic mistake that inexperienced riders make >>>> is >>>> they are cruising along at a good clip, get into a really high gear >>>> because >>>> they are cruising along fast, then they stop at a red light. Then the >>>> light turns green and they are grunting with all their weight on the >>>> pedals >>>> going "darn, this gear is way too high!" and slam the front shifter while >>>> still pedaling with all their might. The solution to that is shift to a >>>> good start-up gear before you come to a stop so there is no shifting under >>>> load. The axiomatic truth of front shifting is that the lighter your >>>> pedaling force the better the front-shift will be. >>>> >>>> 3. What happens during chain-suck is that the chain moves over from >>>> the OLD ring to the NEW ring. For a fraction of a second the chain is >>>> engaged with both. Pedaling force kind of rams the chain into position on >>>> the NEW ring. If the teeth are lined up just right that can make a >>>> pulling >>>> force on the part of the chain that is still on the OLD ring. That can >>>> make the chain "stick" to the teeth of the OLD ring, and so instead of >>>> rolling off the ring, it stays stuck to the old ring and gets pulled up. >>>> Hooked or otherwise damaged teeth can make a ring "stickier". A chain >>>> that's a hair too narrow can make a chain more likely to stick to the ring >>>> and get pulled up. The way the two rings are clocked to each other can >>>> influence the way the teeth line up. I'd recommend you make a black mark >>>> on the 24, and on the crank arm. Then remove the 25 and clock it by 1/5th >>>> a turn. Many 24T rings have an arrow on them and that arrow is intended >>>> to >>>> line up with a similar feature on the 38. Look for those features, see if >>>> they are lined up, and experiment with different orientations. >>>> >>>> 4. Big picture, it seems that a good mechanic who you trust should >>>> look at the bike, and a good rider who you trust should review front >>>> shifting techniques with your wife. One way to think about it is that you >>>> should always shift the front before you need to. The rear is for >>>> shifting >>>> right now because you are in the wrong gear right now. >>>> >>>> 5. These issues are one contributor to why so many bikes today are >>>> 1x. Rear shifting and front shifting are entirely different actions, and >>>> rear shifting is close to fool proof. The only truly fool proof front >>>> shifting is no shifting. >>>> >>>> Finally, never cross chain small-small, EVER, even as an intermediate >>>> step to get to another gear. Small-small is hot lava. Stay away from the >>>> hot lava. Only use the 24 when using the bigger half of the cassette. >>>> >>>> Best of luck getting it sorted. >>>> Bill Lindsay >>>> El Cerrito, CA >>>> On Monday, March 3, 2025 at 6:42:25 AM UTC-8 Bill S wrote: >>>> >>>>> Hi all, >>>>> >>>>> We recently purchased a used Clem H for my wife, and the previous >>>>> owner said she had only ridden the bike about 100 miles. She was the >>>>> second >>>>> owner, and said that the first owner also did not ride the bike much, >>>>> which >>>>> I believe because there really wasn't a scratch on the bike. >>>>> >>>>> On the first ride, when my wife shifted the front derailleur the chain >>>>> sucked up and got stuck in between the chainring and the frame. I was >>>>> able >>>>> to pull it out and we kept riding, but the same thing keeps happening. It >>>>> doesn't happen every time she shifts in the front, but it has happened >>>>> about 5 different times, and has happened every time she's ridden the >>>>> bike. >>>>> >>>>> The front is a double with a small 24 tooth chainring and a large 38 >>>>> tooth with microshift thumb shifters. I can't recreate the issue when the >>>>> bike is in the stand, but I did try putting a new chain on to see if that >>>>> would make a difference. I also put in slightly smaller spacers between >>>>> the >>>>> chainrings and made sure that all the teeth were aligned on each >>>>> chainring, >>>>> but so far nothing has made any difference. This issue has happened when >>>>> shifting from the small ring to the big ring and also from the big ring >>>>> to >>>>> the small ring. >>>>> >>>>> I think the next step is to replace the chainrings, but I am wondering >>>>> if anyone else has had this issue? Should I swap the 38 tooth with a 36 >>>>> or >>>>> a 34 to reduce the difference in size (although I know 38-24 is how it >>>>> comes from Riv)? Maybe I can try putting some zip ties where the chain is >>>>> sucking up into the frame? Is it possible that the wide (26x2.35) tires >>>>> that came with it are causing an issue, since the chain is pretty close >>>>> to >>>>> it? Any insight is appreciated. I've included some photos below. >>>>> >>>>> thanks! >>>>> Bill >>>>> >>>>> [image: IMG_9152.jpg][image: IMG_7098.jpg][image: IMG_7068.jpg] >>>>> [image: IMG_7117.jpg] >>>>> >>>> -- >>>> You received this message because you are subscribed to the Google >>>> Groups "RBW Owners Bunch" group. >>>> To unsubscribe from this group and stop receiving emails from it, send >>>> an email to rbw-owners-bun...@googlegroups.com. >>>> To view this discussion visit >>>> https://groups.google.com/d/msgid/rbw-owners-bunch/35ac60a1-6cbd-4d39-b739-8d39777d4dc3n%40googlegroups.com >>>> >>>> <https://groups.google.com/d/msgid/rbw-owners-bunch/35ac60a1-6cbd-4d39-b739-8d39777d4dc3n%40googlegroups.com?utm_medium=email&utm_source=footer> >>>> . >>>> >>> >>> >>> -- >>> John Robert Williams >>> >>> >>> >>> -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. 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