Loose Headset

[RAGBRAI VI]

I have a Quest with a Dia Compe headset. For the past month or so, I have noticed a little, very little, slack when I pedal hard. Getting off the bike: If I grab a crank arm with one hand and grab the handle bar using the other hand and attempt to turn the front wheel, I can detect a slight movement. The stem is tight and the movement seems to come from the headset. I see there is a video on adjusting this headset, is this something that can be fixed by that or do I have a potentially more serious problem?

 

[Ross Jantz]

I readjusted my Q's headset with the same symptoms and it tightened right up. No guarantees, but it's easy enough that I think it's worth a try.

 

[rfneep]

I agree. Try tightening the headset first. I've had similar experiences with my Q's. Good luck!

 

[billyk]

Here's a rather long discussion of adjusting the Diatech headset. I wrote it for the guy who bought my bike.
------------------

If there is play in the headset (and this will need adjusting after months/years), there's a Cruzbike video about this (

), but please read my comments below as the video is incomplete and the whole thing is needlessly confusing (many comments on the forum).

The diatech is simple in theory, elegant even, but not explained well.

A pair of polished male/female conical rings slide against each other: when the top ring (that is split and has the exterior bolt) is tightened it forces the lower/inner ring down to press on the frame tube.

This only works when the pivot clamp holds down the whole assembly from the top; otherwise the diatech ring will slide up and become loose. If you feel play in the handlebars this is the problem.

In that case loosen both the pivot clamp and the diatech tightening bolt until they move freely (as in the video), then hand-press the pivot clamp down onto the headset and tighten it hard. Hard! (Make sure your 5mm allen wrench is fully seated into the bolt-heads).

=> An extra set of hands makes this easier.

Then tighten the diatech ring until there is => no play but the handlebar still rotates freely <=

It seems complicated but is actually easy once you understand the principle.

If the above doesn't make it tight enough (still has play), or is too tight (anything less than free rotation) loosen both the Diatech and the pivot clamp and start again.

=> Also note (as the video explains) that the split in back of the head tube must align with the splits in both the pivot clamp and the diatech ring.
With the splits aligned, when the clamp and Diatech rings are tightened they slightly compress the head tube. (This is easy to forget when doing the above!).

 

[kdc]

If you haven't already, look further down the forum for "DiaTech headset adjustment" and you'll find some more posts on this. The video, and @billyk' s description should be really helpful. For me, the looseness had to eventually be hammered back down as it had gotten too loose. The DiaTech is, IMHO, a bad design.

Good luck!

 

[agfrag]

I also have a little slack, but I get it when I rotate the handlebars against moderate to heavy resistance like uphill pedaling. My up and down slack on the headset is, as far as I can tell, zero. Matter of fact, I think the Dia Tech adjuster is a little too tight based on the resistance I feel rotating the front with the wheel off the ground.

However...

The rotation reminds me of an old suspension seat I had, the 'slide up and down on a spring' type.
So I was thinking... Could a slight "play" in steering rotation be caused by the front shock system? I mean to say, that since the fork is allowed to move up and down, it's obviously not clamped or welded to the steering tube, so something must be in there keeping the fork from rotating, and I wonder if this could wear down? The seat I had problem turned out to be a worn plastic guide which had a corresponding groove in the sliding shaft of the seatpost.

I wonder if the front shock system uses something similar? And if so, I wonder if the wearing down of the alignment "subsystem" could be causing some steering play?

Anyone ever take one apart?

 

[benphyr]

Your analysis of that play being in the suspension sounds good to me but I have never taken one apart. I have mistaken the cable housings rubbing on each other and the frame for the headset bearings being too tight.

 

[billyk]

Anyone ever take one apart?

Looks like @super slim has. See the thread "Quest front suspension" in late Dec 2017:
http://cruzbike.com/forum/threads/quest-front-suspension.12121/
[Note, edited to correct, thanks @agfrag ]

Also "Q2 front shock rebuild?" in Sep 2017:
http://cruzbike.com/forum/threads/q2-front-shock-rebuild.11950/

Both of these have some photos of the disassembled shock, and (from Super Slim), a diagram originally from John Tolhurst with precise measurements.

I actually have my old fork with shock sitting around (I replaced this with a rigid fork a year ago, to great effect; see comments and photos in the above threads). Are you in or around Seattle by any chance?

 

[billyk]

Looking through my old files, here are 2 pages of instructions from Diacompe/Diatech, showing the order of the various rings. Might be useful to have around if you're taking it apart. But it doesn't show the guts of the shock (see the Tolhurst diagram linked above).

By the way, @agfrag if you're new here you might not have heard of John Tolhurst. He was the designer of the original Cruzbikes and through the early Silvio and Vendettas. He was our guru here for many years, the man.

 

[billyk]

Here's the Tolhurst diagram, saving you the trouble and putting this where we can find it easily.

 

[agfrag]

Thanks billyk, Interesting stuff. I am in South East Michigan fwiw. Btw, it looks like you posted the same link twice, but you left the clue necessary to find the other post.

Looking at the "Quest Front Suspension" post by Christo, the very first pic in it posted by super slim shows the secret I think, rotational movement is prevented by the flattened shape of the upper part of the lower fork assembly "thing" (can't think of a name). And I could be wrong here, but do the large Allen headed screws press somehow against the flat sides of the shaft, which allow the rotational "play" to be firmed up?
I am wary of the last statement, as I don't see any screw end witness marks against the flats of the upper shaft, so maybe the screws press against 'something' between the screw and the flat sides of the shaft maybe?

 

[super slim]

Thanks billyk, Interesting stuff. I am in South East Michigan fwiw. Btw, it looks like you posted the same link twice, but you left the clue necessary to find the other post.

Looking at the "Quest Front Suspension" post by Christo, the very first pic in it posted by super slim shows the secret I think, rotational movement is prevented by the flattened shape of the upper part of the lower fork assembly "thing" (can't think of a name). And I could be wrong here, but do the large Allen headed screws press somehow against the flat sides of the shaft, which allow the rotational "play" to be firmed up?
I am wary of the last statement, as I don't see any screw end witness marks against the flats of the upper shaft, so maybe the screws press against 'something' between the screw and the flat sides of the shaft maybe?

The two screws locate the rectangular to circular guide!
There is some slop between the Aluminium rectangular guide and the rectangular steel section of the fork!

 

[agfrag]

Thanks super slim. Now that makes perfect sense from what I've been seeing. And opens up possibilities for reducing the rotational play.

 

[billyk]

Thanks super slim. Now that makes perfect sense from what I've been seeing. And opens up possibilities for reducing the rotational play.

The looseness of the spring shock is part of a series of flexy things on the front triangle of the early Qs. All of them steal some of your pedaling effort (especially when you really need it, like going uphill), and were fixed with complete redesign of the Q45. But substantial upgrades can be done on the Q2 nevertheless. See the thread below, and having done this I found that the "suspension" provided by the shock headset is minor, and not worth the added flex and consequent power loss. This has nothing to do with the Diatech, just with the spring shock. Ditch the shock, you won't notice the lack of suspension, but will notice the increased power.

"Upgrading a Quest v2"
https://cruzbike.com/forum/threads/upgrading-a-quest-v2.12009/

 

[castlerobber]

I found that the "suspension" provided by the shock headset is minor, and not worth the added flex and consequent power loss.

Another benefit I found from changing to the QX100 fork was increased stability. Riding no-hands got a whole lot easier.

 

[agfrag]

So, I took apart my fork yesterday, to see if there would be any opportunity to "tighten things up" and remove the slack. Wow, what I found was interesting. First of all, my fork internals don't exactly match the diagram in post 10. I only have one spring above the lower fork shaft (pic attached) and I have two holes in the upper tube, but only one has the 2 hex bolts that hold the two half moon pieces in the tube that press against the lower shaft's flat part to prevent rotation. Much to my delight however, there are also two tiny set screws next to these to increase pressure of the half moon alignment pieces against the lower shaft (pic attached)!

But alas, I found some things that made me sad ...
1. There was zero play in the lower shaft. I know this as I attached a small breaker bar to the upper tube and got zero play, it was quite firm. So no opportunity to tighten things up.
2. My upper bearing holder ( the ring of metal that has tabs that hold the bearing balls in place) was destroyed, and a whole bunch of metal pieces came out of the headtube when I removed it. Luckily, I was able to find and keep 21 of the 22 bearing balls.
3. I was missing (if the DiaTech ABN & SBN diagram in post 9 is right) the #7 and #12 seals!
4. The adjusting clamp would not work. Essentially, the #3 adjusting clamp that squeezes against the #4 centering ring had an upper diameter of 1.145in. and the diameter of the tube was 1.125in. So that only allowed 0.020in. of tightening, which didn't raise the adjusting clamp much, if anything. The casting and surfaces of the adjusting clamp looked pretty crudely done, which may account for this diameter issue. I reamed the adjusting clamp top out to about 1.195in., and it worked much better.

So, with uncanny skill, I cleaned up the fork parts and greased the sliding contact surfaces, and reassembled the fork. I got around the upper bearing issue buy putting the balls in a thick grease, and sticking them to the insides of the #9 frame cup, then was really careful not to dislodge them upon reassembly.

Took it for a 14 mile test ride with a lot of bumps, and while the fork did become a little loose, I was able to tighten the adjusting clamp again, and that took care of it, and after this morning's ride on the same route, it held up just fine.

But I'm kinda screwed, as I couldn't find a source for the DiaTech headset online, so I dunno where I'm going to get the seals, and bearing, for that matter.

And as far as I can tell, there is no other way to fix this as without a star nut in the upper tube, you can't use anything but the DiaTech! And you can't put a star nut in the upper tube because there's no room because it's full of spring and stuff.

Which leads me to summarize, that if the upper bearings go bad like mine did ( and probably for every bike built, eventually they all will, nothing lasts forever) unless you opt for a different fork, a very unique fork with the right 135mm wide opening and the tabs for attaching the BB tube, and mounts for disc breaks, etc., then the bike becomes a dust collector.

I sent an email to Cruzbike yesterday inquiring about the replacement fork, and called and left a message about the bearing, I hope I get a response!

 

[agfrag]

Got a response by phone! Robert suggests getting a regular 1 1/8 in. headset, and a Problem Solvers adjustable headset spacer. Also advised to use the Cruzbike Contact form to enquire about ordering the non suspension fork, which I have.

Dunno if anyone has done this particular headset mod yet, but if so, any recommendations for a headset? He recommended the cartridge type.

 

[agfrag]

Well, I should have done more homework on headsets before I posted above. Apparently, headsets (even 'cartridge' ones) come in a variety of kinds, and there is a system called "S.H.I.S" (Standard Headset Identification System) which details data about the headset, and to order the correct headset, you need the following to know the SHIS numbers:

1. Upper headset type
2. Upper frame internal diameter
3. Fork steerer top outside diameter
4. Lower headset type
5. Lower frame internal diameter
6. Fork steerer bottom outside diameter

So for the Quest I have (which has the blue and white logo), I think the data is as follows for what I need:

1. Upper headset type - Zero Stack?
   
2. Upper frame internal diameter - dunno, gotta measure it
   
3. Fork steerer top outside diameter - I think 28.6mm, as this is stamped into the top of my DiaTech
   
4. Lower headset type - Zero Stack?
   
5. Lower frame internal diameter - dunno, gotta measure it, but I think it's the same as the top
   
6. Fork steerer bottom outside diameter - I think it's the same for top and bottom, so I'll go with 28.6mm

To save time, plus I don't want to take the whole thing apart again, does anyone know the SHIS numbers for the DiaTech Headset? That would be awesome.

 

[billyk]

I don't get all this angst about the headset. Cruzbike will sell you a nonsuspended fork, you'll replace the old one, give it a ride, and wonder why you wasted all this time on the suspension fork. This stuff is all over this forum. You're not the first one to go through this.

Am I missing something?

 

[agfrag]

Yes, sorry billyk, it’s buried in one of my overly verbose posts above, my upper bearing’s ball holder is destroyed, and my lower bearing is missing the seals. I found out talking to Robert the DiaTech is no longer available, so Robert suggested getting a new cassette headset. But I don’t know what size(s).