Help with frame related questions

[Biggsy]

Leave the headset alone.  You don't want to dampen the steering when you might be able to solve the root cause - perhaps via a slight change of riding position via a stem/seatpost adjustment.

[LittleWheelsandBig]

Good luck with that approach

[Biggsy]

I had luck with that with my Raleigh Royal.  No hint of shimmy in the 20 years since.

[Ian H]

An acquaintance of mine cured shimmy on his Longstaff Trike ("Don't you dare tell George.") by replacing the top set of ball bearings with a section of flexible metal tube from a brake cable outer.

Not, however, recommended for a two-wheel machine, not even a Longstaff.

[Dtcman]

Dave

I have a Harry Hall 653 steel framed audax bike (similar to the Hewett Cheviot). I’ve changed from Cantis to V brakes on the front and always had trouble aligning them. I’ve now realised that the wheel rim isn’t central between the fork blades but is bob-on in the wheel building jig. There’s no sign of damage and I guess they’ve like it from new. It’s as though one blade is fractionally longer than the other. The obvious bodge fix seems to be to lengthen the drop-out on one side slightly 0.5-1mm max I would guess.

Any reason that wouldn’t work?

[mzjo]

An acquaintance of mine cured shimmy on his Longstaff Trike ("Don't you dare tell George.") by replacing the top set of ball bearings with a section of flexible metal tube from a brake cable outer.

Not, however, recommended for a two-wheel machine, not even a Longstaff.

The bodge on vintage motorcycle-sidecar outfits with cone bearings was to replace the balls in one or both races with a brass curtain ring to reduce the steering wobble.

[Bicycle Repair Man]

Dave

I have a Harry Hall 653 steel framed audax bike (similar to the Hewett Cheviot). I’ve changed from Cantis to V brakes on the front and always had trouble aligning them. I’ve now realised that the wheel rim isn’t central between the fork blades but is bob-on in the wheel building jig. There’s no sign of damage and I guess they’ve like it from new. It’s as though one blade is fractionally longer than the other. The obvious bodge fix seems to be to lengthen the drop-out on one side slightly 0.5-1mm max I would guess.

Any reason that wouldn’t work?

Now then !
First check is to turn the wheel round ie left to right. If the wheel is still over to the same side then the forks are indeed out. The best fix if this is the case is to file a small amount out of the dropout that is on the "long" side with a round file that fits the curve of the dropout slot. I find a 10" round second cut works best, but it does depend on the file. Dropouts by and large have plenty of metal to allow this to be done without any risk at all. You must keep checking the wheel centering as you proceed. A drop of thinned hammerite smooth on the bare metal will prevent it rusting.
Good luck

Dave Yates

[Bicycle Repair Man]

This is bugging the hell out of me!

I can induce front wheel wobble/oscillation at any speed so far (still experimenting) between 12.5mph and 21mph by simple taking my hands off the bars and almost sitting upright. The further forward I lean, the less the effect, also the further back/upright, the wobble diminishes. The oscillation never gets uncontrollable or scary like a tank slapper at very high speed - I can ride and watch or feel the bars wobble without losing absolute control. It can also be produced by taking only one hand off the bars - which is how i discovered it - hand signalling - I don't make a habit of riding no hands!

It appears to start sooner with more of a load in the saddlebag or when using rear panniers. I went on a jaunt last week with heavily loaded (small Super Cs) on the rear and a lightly loaded barbag. The "shimmy" was way more pronounced, even at lower speeds and sometimes with both hands on the bars. It was still just about controllable.

At speeds in excess of 20mph it's rock solid, loaded or not - which took a lot of confidence building on my part, having had a tank slapper on another frame and could only see death, fortunately avoided with buttocks and knees automatically clenching the saddle nose and top tube respectively!

The frame is a Longstaff tourer which I bought new from George in 1993 - heavily ridden and toured with solid as a rock predictable steering for many years. I had it refurbished in 2007 (by Longstaff's), when I requested the 1" steerer tube to be replaced to make it 1" Ahead compatible. It looked so naff (traditional lugged frame with UGLY chunky Ahead stem = FAIL on my part ) I reverted to the more elegant quill stem and cut the steerer tube down and threaded it. A new Ultegra threaded headset was fitted.

This is when I suspected/imagined? a different feel to the bike? I kept checking the adjustment of the headset - I still keep checking and have had it checked - it is properly adjusted.

The front wheel has been changed to a Shimano 3N71 dyno hub model. I've checked the frame over for cracks. I've checked the alignment of frame front to back.

Suggestions? PLEASE??

Further thought - what could be the outcome of not threading the steerer "square"?

Now then Slope
Sorry about the delay in replying I have been stupidly busy the last couple of weeks combined with a nasty attack of Dutch Lurgie courtesy of one of my framebuilding course pupils.
Over the past 37 years that I have been building frames I have come across this problem  fairly regularly.  If the bike rode OK before then clearly something has changed.
It sounds as if the trail has altered. This could happen if the new column was put in at a slightly different angle to the original thus altering the offset.  First check that the fork blades are in line with the steering axis. Do you know what the original fork offset was.
Is the dynohub wheel the original? if not have you tried it with the original, or near offer, wheel
The effect of theading the column off square would be a bit of a tight spot somewere as it turns.
The weight distibution thing is consistent with a lot of examples of this problem that I have seen most of which have been cured by altering the fork offset however there are too many variables to give a firm reply. Sorry to be a bit vague but I normally solve this sort of thing "hands on" rather than by electronic means.
My money would be on the fork offset.

Cheers

Dave Yates

[slope]

This is bugging the hell out of me! . . . . . .

Now then Slope . . . . . . .

Cheers

Dave Yates

Thanks Mr Yates - I will respond with more info tomorrow and DO realise it's hardly a straightforward problem

[Dtcman]

Dave

I have a Harry Hall 653 steel framed audax bike (similar to the Hewett Cheviot). I’ve changed from Cantis to V brakes on the front and always had trouble aligning them. I’ve now realised that the wheel rim isn’t central between the fork blades but is bob-on in the wheel building jig. There’s no sign of damage and I guess they’ve like it from new. It’s as though one blade is fractionally longer than the other. The obvious bodge fix seems to be to lengthen the drop-out on one side slightly 0.5-1mm max I would guess.

Any reason that wouldn’t work?

Now then !
First check is to turn the wheel round ie left to right. If the wheel is still over to the same side then the forks are indeed out. The best fix if this is the case is to file a small amount out of the dropout that is on the "long" side with a round file that fits the curve of the dropout slot. I find a 10" round second cut works best, but it does depend on the file. Dropouts by and large have plenty of metal to allow this to be done without any risk at all. You must keep checking the wheel centering as you proceed. A drop of thinned hammerite smooth on the bare metal will prevent it rusting.
Good luck

Dave Yates

Thanks Dave I'll give it a go.

[closetleftie]

Hi Dave,


I have a 531* frame which I think is built for 27" wheels. It has canti bosses but the fork crown is also drilled for caliper brakes. Currently powder coated and used for going to the pub!


It needs a respray and I would like to convert it from threaded to threadless steerer, so some work is required anyway. Can the frame be converted to be compatible with 57mm drop dual pivot brakes in the process, so that I can put a modern STi groupset on it?


Thanks!

Leftie


*Well, it has a 531 sticker on when I bought it...

[contango]

Hi Dave, saw this thread and figured you might be able to give me some pointers.

I've got a cyclocross bike (2009 Specialized Tricross Sport Triple) that I use for day-to-day use, touring, the odd audax etc. It's got cantilever brakes and having recently ridden a bike with caliper brakes I came to realise how much better they are at stopping the bike. I'm looking at the fork and frame of the tricross and trying to figure if it's a sensible (or even a possible) option to mount caliper brakes to the fork and frame. It's got what look like mounting points there but I can't tell if they are designed to take a caliper brake or if they are intended for nothing more than a mudguard.

Hi Contango

Alas, I dont think this is a practical proposition. Being a cross bike the clearance between possible caliper brake mounting points and the centre of the rim brake surface will be too great. You need to measure from centre of brake hole to middle of braking surface on the wheel. If it is greater than 57mm then forget it. You may find deeper brakes but they will not work as efficiently and would feel soft.
It would be worth checking the set up of your cantis. For best effect you should see an angle of approx 90 degrees between a line from pivot bolt centre to straddle wire clamp and the straddle wire.

Cheers

Dave Yates

Ack, shamefully late in coming back to the thread, too many threads here to keep on top of them all. Thanks for your feedback, I'll take a look at how my cantis are set up and tweak as necessary. If I can get a bit more stopping power out of them it may be I don't need to look at calipers, I guess if I can lock both wheels then I've got more than enough stopping power.

[ran doner]

Ack, shamefully late in coming back to the thread, too many threads here to keep on top of them all. Thanks for your feedback, I'll take a look at how my cantis are set up and tweak as necessary. If I can get a bit more stopping power out of them it may be I don't need to look at calipers, I guess if I can lock both wheels then I've got more than enough stopping power.

I replaced my tektro cantis on my 2010 tricross with these FSA cantis with some Kool Stop pads and the improvement was instantly apparent.

[BrianI]

Ack, shamefully late in coming back to the thread, too many threads here to keep on top of them all. Thanks for your feedback, I'll take a look at how my cantis are set up and tweak as necessary. If I can get a bit more stopping power out of them it may be I don't need to look at calipers, I guess if I can lock both wheels then I've got more than enough stopping power.

I replaced my tektro cantis on my 2010 tricross with these FSA cantis with some Kool Stop pads and the improvement was instantly apparent.

Tektro CR520/720s are a good option too.  I have these on my dawes horizon.

[Biggsy]

Hi Dave,

I have a 531* frame which I think is built for 27" wheels. It has canti bosses but the fork crown is also drilled for caliper brakes. Currently powder coated and used for going to the pub!

It needs a respray and I would like to convert it from threaded to threadless steerer, so some work is required anyway. Can the frame be converted to be compatible with 57mm drop dual pivot brakes in the process, so that I can put a modern STi groupset on it?

While you're waiting for Dave, I can tell you that you will be able to fit dual-pivot brakes, though deeper than 57 mm is needed in some cases.  It depends on the particular frame.  I fitted modern components to my old Raleigh Royal that originally had 27" wheels.

[closetleftie]

Thanks Biggsy,

I did run 70mm Alhonga DPs for a while. They weren't as good as 57mm ones though - bit more spongy, which I assume to be because there is more flex in the longer "arms". If I wasn't thinking of converting to a threadless steerer anyway, that's certainly what I would do again.

[Biggsy]

Try measuring.  http://sheldonbrown.com/calipers.html#reach 



An extra couple of mm of reach can be got from a calliper by filing the bottoms of the brake block slots.

My front Alhonga feels ok, thanks to being able to have the blocks at the top of the slots, effectively minimising arm length.  The rear is rather spongy, but I don't mind having a weak rear brake.

[closetleftie]

Sorry - I should have made myself clearer. The frame definitely won't take 57mm drop brakes as it is. The reach required is around 65-70mm at a guess. The Alhonga deep drop brakes were pretty near maxed out from memory.

[Biggsy]

Oh right.  You could stick with standard cantis.  They're compatible with STI brake levers.

[closetleftie]

But not with easy set-up, at least in my hands. 

[Dtcman]

mini V brakes will also work directly with drop leavers. Easier to set up than cantis and no hanger required.

[Vince]

As reported on the 'On the Commute' Thread, I have had the misfortune to sheer the steerer tube of my Mercian.



Mercian will replace the tube and respray the fork for 120 quid. However, I'm concerned that at around 35 years old, the frame may have reached it's end of life. Tubes are 531 DB.

Any views on extending the life of this frame? Is another failure somewhere else on the frame likely?

[aidan.f]

I would be  interested  in  DY's  opinion of  roller bearing  headsets - I gather they stress the  steering  tube axially. (I may have  just answered my own question).

[Pedaldog.]

I want to build a Dutchbike from the Atomic Zombie plans. It uses a lot of sourcable bike parts but the main frame is square tube, Steel or Cro-mo. Any ideas of where to pick up good quality tubing for this project?

[Rhys W]

I have a question for Dave.

I have a nice steel frame that I use for winter clubruns, a Pinarello Sestriere made out of their own-brand "Forma" Cr-Mo tubing. Lovely frame, rides like a dream, Italian style but clearance for mudguards. I noticed some bumps on the underside of the chainstays which felt like paint drips, but on further inspection turned out to be little bubbles of rust under the paint:



Obviously some failure of preparation before the frame was painted. I sanded off any loose flakes/rust, applied some rust inhibitor and covered it in primer as an interim measure. I'm thinking of getting it resprayed now as it's also lacking a second set of bottle cage bosses. My question is, would this be "cured" by shotblasting and a good (professional) respray? I don't want to spend £150+ for the rust to return in a few months time.

I notice that Argos offers something called "Primer rust pitting from: £50", which seems rather expensive?