Mountain Bike Reviews Forum banner
1 - 20 of 22 Posts

·
Registered
Joined
·
663 Posts
Discussion Starter · #1 ·
First I thought it was a coinsidence but lately I saw 3 differant frames from 3 differant brands break at the non drive side chainstay near the dropout.
Then I realized all these frames had sliding dropouts.
When I thought about it, the only thing that came to mind is that because the rear wheel axle / brake caliper is further back, it may apply more forces on the CS which may cause this problem. What do you think, coinsidence or something to pay attention to ? (I noticed some frame makers adding a little tube to strenghen that area)
 

·
Registered
Joined
·
927 Posts
On my sliders I noticed that I had to be attentive to the non drive side slider bolts, as they came loose twice over the first 400 miles, but have been staying tight over the past 200 miles or so.

If the bolts become loose I think they can place abnormal stress on the frame.

my .02 cents
 

·
Misfit Psycles
Joined
·
2,772 Posts
In some cases the material used for the slider is beefier then the point of attachment on the frame. The forces are transfered and pop.

Primarily steel frames (that I have seen) where designers get a little over creative and confident...forgetting the 'leverage' created.

I would propose that MOST slider systems thought through the process completely and adequately.
 

·
Having a nice day!
Joined
·
1,422 Posts
When I had my steel frame built this fall, the builder and I discussed this very thing. He was for adding a little brace, and so was I. Better safe than sorry. Here is what he came up with. So far so good.

 

·
Registered
Joined
·
2,501 Posts
i hate sliding dropouts... hate them hate them hate them!!
ugly, overly complicated looking solution to something that wasn't a problem (imo)

that said, my current frame, misfit dissent, has them and I haven't had ANY PROBLEMS WHATSOEVER.
*shrug* personal opinion is only worth so much right? ;)

my issue with them in general (and the paragon ones more specifically)
is that they're duplicating the problems of the old cannondale cantilevered dropouts. axle force wantsa go up, frame isn't moving. If force is enough, something wants to give.

this may be a horrible diagram but it should make the point

impact force (red arrow) aimed at blue dot (rear axle) produces a rotational force (orange arrow)
this force is rotating largely because the framework holding the axle in place is usually angled (seatstays doncha know... hey maybe this is why the OS Blackbucks have near vertical seatstays (after a neat curve up top?)
So the frame's holding the front of that plate in place, and the back of that plate (where the axle is) is trying to move... and even though you yourself may never notice it, I'm certain even on YOUR bike it probably does move a tiny bit every ride.

I digress... the back part of the sliding dropouts plate (where the axle is) is left unsupported and tries to move upwards.
Since it's welded on to the seat and chainstays, if the force is enough to overcome the material's strength, the front of that plate tries to remove itself from the frame.
Rupture in the chainstays and seatstays could ensue (depending on how well the frame's made!)
Those typical locations would be the green dots.

You want to diffuse the stresses incurred with this type of dropout? gusset the TOP of the plate the dropouts bolt to, this'll distribute the forces along the seatstay's length (where they're supposed to be, and are in conventional frame, except for the aforementioned cannondales with the canti'd dropouts which cracked off... ahem!)

Sure, gusset between the chain and seat stays, that helps too (anything strengthening the whole assembly is going to be a good idea!), but to prevent this attempt at rotational force there should be more buttressing of the far back end of that damn dropout mount.

Where's my trick builders with spidey-web gussets?
Yes brant, your on-ones suffer from none of this due to their chainstay mounted brakes... and most bikes with horizontal dropouts don't have the same problem as those with sliders.
But this is a simple example of how and why too much stress in that particular location is going to try and twist the dropout off (which let's face it is a rather unusual frame failure to plan for!)
Let's not forget that the brake force is transferred through the bolts that attach the actual dropouts to those slots and the force is NOT transmitted to the frame itself in the way frame are used to.
The entire brake-side dropout plate which carries the caliper itself is just trying to rotate around with the rotor, and those bolts in the slots (and any keying of the dropout itself) are the only thing preventing it from doing so.

The axle force is acting along the length of the sliding dropout, the force from the axle itself being a couple inches BEHIND the bolts of the dropout is actually giving it a LEVER, leverage against the bolts and keyed surface holding it on.
BADBADBADMOJO

*sigh*
Too much coffee, shutting up now.
 

Attachments

·
Having a nice day!
Joined
·
1,422 Posts
I hear you, and like anything, it is a compromise. I had an EBB before and liked, until it started creaking. I guess the only other good option would be the ENO hub, but I'm not real fond of that one either. Just another reason to lose weight and reduce the braking forces!
 

·
Registered
Joined
·
2,501 Posts
LoneStar said:
I hear you, and like anything, it is a compromise. I had an EBB before and liked, until it started creaking. I guess the only other good option would be the ENO hub, but I'm not real fond of that one either. Just another reason to lose weight and reduce the braking forces!
or run a trackie rear hub :D
horizontal dropouts... takes more than 20 seconds to even them up, they're nowhere near as aesthetically pleasing as the perfect verts you get with ebb's... but I still love them... :thumbsup:
 

·
Registered
Joined
·
195 Posts
Yea,
I have sliding dropouts on my main SS rig (use a Singlenator on my other convert SS) and while I have had no problems yet I can't really get used to the idea. In fact, conceptually I am starting to prefer a chain tensioner. The ENO hub seems like another alternative. EBBs gives me headaches just thinking about em.
 

·
Registered
Joined
·
662 Posts
Interesting points for sure!

I've had no problems with the sliders on my Monocog Flight and have yet to hear of any failures on the chainstays or the seatstays of that frame. I really like the sliders' simplicity and easy of adjustability. Wheel changes are easy and the alignment of the disc caliper is a no-brainer.

byknuts said:
Let's not forget that the brake force is transferred through the bolts that attach the actual dropouts to those slots and the force is NOT transmitted to the frame itself in the way frame are used to.
I think you raise some interesting points and I'd be curious to hear thoughts from additional builders - particularly Ground-Up Designs as I've heard that Eric was the first one to use the sliders and Paragon's came out shortly after his designs.

My own sense is that once the slider is sufficiently tightened the bolts don't take the force - but rather it is spread along all contact points between the slider and the frame's slider slot and with no room to wiggle it should act as a solid unit... but again, cracks in the frames would indicate that clearly there are a few things that might've been overlooked. I'll watch the stays on my Flight closely...

What were the frames that you've seen cracks? I don't want to start a slamming-fest of frames - but it'd be good to know how they're dealing with it... I'm guessing that most would recognize a design error and fix or replace the frame with one that doesn't do that.

I look forward to hearing feedback from additional frame designers...

Good post. Thanks,
S
 

·
SSolo, on your left!
Joined
·
2,577 Posts
Very interesting thread, I'm kinda paranoid of sliding dropouts but own a bike like this. I searched and asked around before I bought it. :D I adjusted and torqued to specs as mfr calls for.
 

·
Fo' Bidniz in da haus
Joined
·
17,287 Posts
they, along with EBBs, are nothing more than a solution looking for a problem. I will never own a SS with either again as there is NO advantage to them at all on the trail...sure some tool may say its nice to be able to change your chainstay length but GMAFB. And only a retard will argue that vertical dropouts make life that much easier...how often are you changing a friggin tire/tube and how friggin hard is it to tighten up two bolts on a bolt on hub in a horizontal!? GMAFB...
 

·
Registered
Joined
·
129 Posts
I know most will ostracize this opinion, but I own an 18" Vassago Optimus Ti with Paragon sliders and an 18" steel Vassago Jabberwocky with simple horizontals - the steel Jabber is hands down a finer ride in every respect period. Feels more solid, more comfortable and as Fo said, simple to adjust the rear wheel and brake.

I lied to myself trying to justify the extra expense of the trick Ti frame. The Optimus is a fine piece of work, but save your bones, simple is better. The area near the Optimus slider is pretty burley, but I still worry about it.
 

·
Fo' Bidniz in da haus
Joined
·
17,287 Posts
Celt said:
I know most will ostracize this opinion, but I own an 18" Vassago Optimus Ti with Paragon sliders and an 18" steel Vassago Jabberwocky with simple horizontals - the steel Jabber is hands down a finer ride in every respect period. Feels more solid, more comfortable and as Fo said, simple to adjust the rear wheel and brake.

I lied to myself trying to justify the extra expense of the trick Ti frame. The Optimus is a fine piece of work, but save your bones, simple is better. The area near the Optimus slider is pretty burley, but I still worry about it.
well said
 

·
Registered
Joined
·
1,849 Posts
Some folks want the option of going geared, with an existing or light rear wheel, so they don't want a bolt-on rear hub. Some people take their wheels off and stuff the remains in their car. Some just aren't mechanically-minded and don't want the stress of getting a wheel in straight. That's OK.

Sliders are taking the force that used to flex the SS(and put a smaller torque on the CS/ D/O junction) and use it to place a torque on the entire left D/O. Beefier tube selection will probably withstand this, but nobody has done any testing. If an ME were to run FEA on it, you'd see definite hot spots at the tube/ D/O junctions. No doubt, IMO. Yes, I'm trying to use as many acronyms as I can. F.U....J.K.!

I originally thought that the integrated dropout/disk tabs, like I.F. and Seven use would be problematic. Not because of braking forces -they handle those very well- but because normal vertical bump force and the torque it creates would put additional stress on the welded joints, sort of like a bizarro-world slider.. So far, I've heard of no issues, so go figure.
 

·
Registered
Joined
·
599 Posts
This topic has been being played out a lot recently. The earlier frames without bracing on the disc side must now be hitting the mileage/abuse levels causing them to fail, or maybe been being used often enough on enough frames that things are being thought through a little more. I haven't had a bike with them yet and don't know if I ever will. The EBB I own has been trouble free for about 500 miles of nasty abuse, and well track ends are track ends. On One has particularly thought out a cool disc mount, and the Monocog, Surly, Titus and many other frames with with track ends and adjustable caliper mounts work so well.

Track ends have been around for a long long time, and will continue to be. You can also argue the whole adjustable chainstay length thing with either Track ends or EBB (only technically on an ebb frame as your wheelbase stays the same.) Not saying that sliders aren't good, I will just steer clear until something comes my way I can't say no to that has them.

That being said I will thow in what someone reminded me of the other day on here. Specialized and Trek have both designed a stacked type slider that makes the dropout shorter and makes the stays come together in a better way. Maybe if things went that route it would work out better.
 

·
Registered
Joined
·
599 Posts
I was going to add to the end of my post if anyone had thought of doing just what you suggested. Weld or braze the stays in the middle of the sliding dropout mount. Do you have any issuse running the sliders all the way forward and having the caliper contact the seatstay. I assume that you wouldn't have made the frame the way it is if it did. Good idea! The use of larger diameter/thicker guage tubing at the slider is obviously critical. Awesome looking frames.
 
1 - 20 of 22 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top