I have heard from several builders that the horizontal sliders slip underload. In some instances, they slip enough to bend the tensioning screw.
The questions I pose are:
- What are people’s experiences and opinions about dropouts slipping? Does the DS or NDS slip?
- Is there something we can do about it?
I can think of two potential solutions:
- Increasing the friction forces
- Angling the dropout (to increase the friction)
These dropouts rely on friction to hold the sliders in place. On the bolt side, there is a stainless steel washer:
What if we were to replace this washer with a gnarled surface?
Or an even more engineered solution, a 3M Friction Shim, which uses steel shims coated with diamonds, claiming a 5x increase in friction. Or another supplier: Sintex
If we angle the slider ~7.5deg to be in line with the chainstay, instead of horizontally you theoretically reduce the parallel sliding force by ~1%, but you increase the normal forces by 13%. These normal forces increase the friction and help “jam” the slider to prevent it from sliding.
What are people’s thoughts and experiences?
Update: I contacted 3M and Sintex on 11/30/22 to inquire about friction shims. I’ll update the thread if I hear back!
Update: Jeff L. at 3M got back to me, and they offered to send some M8 samples! As an engineer, I get unreasonably excited over these small things.
Some notable info:
- Shims are a .1mm thick carbon steel sheet with a ceramic coating process, bringing the thickness to .13-.23mm
- Available in 25, 35, 55 grade, which refers to the surface roughness. It is suggested that the surface roughness of the shim and the part match
- Shims are reusable
- Shims can handle salty/wet environments
- Shims maintain performance after getting oily
I’m purposefully keeping the cost off the public record. All I will say is that the cost is on the same order of magnitude as the existing components.
15343 3M Friction Shims Technical Data Sheet 9800421 Rev G.pdf (2.3 MB)
A great solution is belleville washers , the are convex washers and have very high clamping force. I will be using them on my slider plate dropouts coming out soon. They likely are much cheaper then the 3M product.
I personally have never had issues with the inserts slipping.
@BikeFabSupply Belleville washers help keep the bolts under tension with vibration and material creep, but I don’t think they increase the clamping force.
The friction shim works in an entirely different pathway than bolt torque and tension. The current state of the art is: if it slips, tighten it more. This tech has the potential to get around that.
In theory, If you can get a shim between the aluminum slider and the steel dropout, you have 4x the friction to hold the slider in place. It gives you more security, allows you to use less torque, or even use smaller bolts. Purely theory crafting here, it needs to be tested.
I know one of the reasons why people use titanium bolts on the slider is for the 6mm head, which allows you to crank down on the bolt (>20Nm). The shim has the potential to solve this problem at a lower cost. I would guestimate the cost of the shim to be ~$4-5 and would need to order 300 of them.
Sorry, it’s time for me to bail on the forum.
Belleville washers are essentially designed to limit the clamping force, since they’re a compressible spring element, so I’m not sure they’re a good choice in an application where you’re trying to maximize friction. What was your thinking in this case, perhaps I’m missing a good reason…?
the main reasons I looked at Belleville washers , was from what I read they provide a tighter connection with less load, have anti vibration as they maintain the pre-load which keep things from loosing. The top side is grooved as well to hold better the connection. I got this from several washer manufacturers websites. All this to me says you should not deal with slider slipping because of bolts loosening during riding. On the M5 for machined sliders or M3 screw on cast ones I only consider these for the initial setup, All the holding should be done strictly by the fasteners. A little blue loctite on the bolts probably wouldn’t hurt anything either.
These washers also are a cheap upgraded option as part of standard fastener setup and would be better than a standard flat washer that comes with most all slider systems. I do think in some way that double hole flat washer may play a roll in things coming loose versus two single washers , and since that was the specific dropout mentioned. I have no facts to back that up though. Just observation from the OP, and that it may be not getting even clamping force all around that style of washer. In addition that the flange being stainless and a harder surface vs cast 4130 or 1018 steel could play role in getting a good bite. One thing on my machined sliders the insert to flange is a pretty dang tight fit. So they have quite a bit of friction already.
For the same reason as Walt I do not see it as a huge issue overall. I have sold likely around 500-700 sets of slider whether the cast steel ones or our machined steel one, and never had a complaint with regards to inserts have issues slipping. I only have a few sets of the plate flanges with stainless faces out there and one of the main things I wanted feedback was this fastener setup. No issues to date of problems, and a want to hear them if there is. I did clamp a set of the BFS plate flanges in the vice to hold it still and see if I could get the insert to to slide. I can say with the Belleville washers the slider insert did not move. Though I did not try to see if any different with a standard flat washer so there is that. Of course no vibration of actual riding on road/gravel/dirt playing a role on that test either. Hahah just a guy yanking on his metal
Probably more long winded than yall want, No one way to get it all done , probably couple right ways and couple wrong ways. Always the best place is in real world application I think. As a note I always like to hear feedback on our parts, good/bad/indifferent , its the only way I can make them better.
I’ve had two bikes with adjustable dropouts, and have had issues at various times with both. I ride mostly single speed and I’m ~195 lbs, so while not elite in terms of strength or fitness, I can still bring a solid Honda Civic level of torque to the table when I’m near stall speed with all of my weight plus however much more I can pull down into the pedals.
First: Salsa Mukluk with Alternator (Gen 1) dropouts. This was an aluminum frame bike so paint on the bike and paint (I think, struggling to remember) on the insert side as well. The stop screw prevented any slippage, but often I would get creaking, and it would have slipped without the stop screw. Rigorous and frequent cleaning of the mating surfaces would mitigate the problems.
Not my bike, but an example:
Second: Kona Wozo with Kona’s version of a sliding dropout, modified. What I like about the Kona design is the bolts are spaced further apart fore-aft than the Paragon design to better resist the bending moment generated by vertical loads at the wheel end (although I’ve never seen or heard of a Paragon one failing, so probably a non-issue). Also, the bolts are beefy so a fair bit of torque can be applied to increase the clamp load in the joint. The downside to the larger fastener, however, is that the bolt may actually stretch less, especially since the grip length of the faster in this case is short, meaning that the joint is more susceptible to loosening as embedment occurs on the interface. The paint on my purple Kona has been the worst I’ve ever owned. It flakes if you look at it funny, let alone ride the bike off-road. I’ve had to debride and sand the mating surface on the bolt head side as the paint has flaked off, and the dropout performance has gotten worse as the interface as gotten less perfect. This dropout slips or wants to slip under pedaling torque, and I’ve bent and broken the anti-slip screws since I prefer to run the bike long CS, so the screw, which comes in from the front, is at max extension. The next thing I plan to try is a spacer to increase the grip length of the bolt. I need to talk about my modfication: I designed and had CNC’d my own inserts to lengthen the chainstays even further, so while I faithfully reproduced the interface geometry, I’ve increased the working loads the joint needs to withstand, so don’t blame Kona or judge their product by my experience!!
My inserts (plus 10mm effective chainstay length):
In summary - my take:
Bolts joints have the easiest time when the loads are in tension/ compression and all of these slider types are friction/shear joints, so we are playing from behind a bit. There are many examples of successful shear joints, so they obviously can and do work, it just isn’t as easy.
With short fasteners, there is limited opportunity for the bolt to actually stretch elastically. This means the joints are very susceptible to loosening via embedment, as the steel fastener head locally mars the softer aluminum, or contamination pushes into a paint or powdercoat surface.
I initially had some Paragon sliders slip then I actually managed to round the 5mm button head bolts while torquing them up super tight. I swapped to some 16mm long M8 socket head bolts that take a 6mm hex as per Walt’s recommendation on MTBR (link below). Haven’t had any issues since running either gears or SS. The bolts I got are boring old A4-70 stainless since I couldn’t justify postage from the US on the Ti Paragon ones.
I have a Lynskey made bike with their paragon style clone sliders. I have never once had them slip, but in dry conditions they definitely creak no matter what I do to tight them down. The hardware is upgraded to the Paragon ti bolts and the plate as seen in the first post. That said, they have generally been more quiet than any EBB I’ve owned. The frame is 13 years old and I’ve often wondered if its just wear on the softer alloy extruded piece that slides in in the harder Ti dropout that is allowing for some minuscule movement.
We rarely have riders calling about sliders slipping, but it does occasionally happen. Usually this involves the left side, where hard braking and/or large rotors will move the wheel to the rear, away from the adjusting screw.
Some important points to keep in mind:
Keep the inserts and frame components free of paint and lubricants.
Because the inserts are meant to move, there has to be clearance. This can lead to small amounts of movement, which can cause creaking. DO NOT LUBRICATE! Lubricants will quiet the creaking, because the lubricant allows movement to take place quietly. Instead, disassemble, clean the components well, and re-assemble. The goal is to prevent movement to prevent noise. Using screws that are easier to torque will help, but there is a limit. Daniel’s diamond friction washers from 3M appear to be a good solution, in particular the oval one that is between the frame component and the insert.
Inserts are a wear item, same as tires or a chain. Replace as necessary.
Blue LocTite on the M8 screws will minimize loosening, and can be re-torqued several times before needing to be replaced.
This is great advice Mark. IIRC I greased the inserts prior to installing them so that must have been what allowed them to move unless really torqued. Will give them a clean up next time the bikes in the stand. Cheers!