1simplexnut

Check out the gap on this fork !
Had a home made bolt/hanger adaptor fitted to make the suntour superbe caliper it came with fit.

The rear brake bridge appears pretty normal spacing .

What were they thinking ?

Any thoughts on what brake calipers would have been originally?

Frame is from the 1970s .

agmetal

Tektro R559 should work. What size wheels do you have on there? If they're 700C that would partially explain it, but even if they were 27", it'd only save you 4mm, so that's still pretty extreme....



Further thought: a lot of center-pull calipers have pretty long reach...

HTupolev

Are you sure that's the original (or original sized) wheel?

gugie 

You have choices.

Brakes for Bicycles from Harris Cyclery

unworthy1

did you try 27" wheels in it? Any chance this fork was not original to the frame? You say it (both frame and fork?) are from the 1970s but at a glance and with nothing else for background this style fork seems like a pretty LATE '70s style, if not '80s.

SkyDog75

Like agmetal said, lots of old centerpulls would have enough reach. Long-reach MAFAC Racers max out at 68 mm reach, so they could work. Weinmann and Dia-Compe 750's have even more reach. Those 750's were typically used on rear wheels, though, paired with a shorter 610 up front. If you were to use a 750, you may have to 'borrow' a longer bolt from a 610.

Modern Tektro R559 dual pivot calipers have 55-73 mm reach, so they'd work well if you don't mind something that's not period correct. They're available in nutted versions (as opposed to recessed) to work with older bikes.

Salamandrine 

It's probably more than a little confusing that what were called at the time medium or normal reach brakes (47-57) are now called long reach, and long reach brakes are called "extra long reach". I don't know if this is common practice or unique to Sheldon Brown and Harris Cyclery. I'm inclined to call them wrong, but of course it is just semantics.

Regardless it appears that this bike was designed for long reach brakes. The old kind. Like Dia Compe 750. Most likely it was also designed for 27" wheels. Hard to be sure with just a picture of a fork crown and no other info though.

Oh, the main why would be clearance for a 27 x 1 1/4 touring tire, as well as a fender, most likely.

gugie 

Yeah, lots of verbiage in place of specs. I suppose Harris was just trying to organize the brakes in a way that made some sense.

I think you nailed it-DC 750's. With that kind of clearance I'd be tempted to go fattie and braze on some canti's or centerpull posts. It'd be interesting to see what size tire would fit in the back.

verktyg 

Something else to consider... The bike could have been in a front ender which took some of the bend out of the fork blades making them longer.

I've seen this before without any damage to the frame. Measure the fork rake with a yard stick or some other kind of straight edge held parallel to the head tube. Measure the rake with a short ruler. It should be ~40mm to 60mm.

Tektro makes some long reach dual pivot brakes. Long reach single pivot side pull and center pull brakes don't have adequate rigidity for good stopping power.

verktyg

Chas.

1simplexnut

hi guys thanks for all the input . Much appreciated .
Positive the forks are original . It is off an old NZ made Mitchell . Tentatively dated in the seventies because of lack of brazeons etc .
Mitchell was manufacturing in the early 80s but would have expected top tube cable guides . This bike has none .

pictures of complete bike here
https://www.flickr.com/photos/704884...57665218590380

Have tried some weinmann center pull ( not sure which model ) and it was too short . The rear worked (just) with pads pushed right to the top of slot.

1simplexnut

Hi have tried with 27" wheel I have . Didnt make a whole lot of difference to the problem

1simplexnut

Hi have tried both . 27" didnt make much difference. fork is original
Have added a flickr link to complete bike pics

1simplexnut

[QUOTE=SkyDog75;18639315]Like agmetal said, lots of old centerpulls would have enough reach. Long-reach MAFAC Racers max out at 68 mm reach, so they could work. Weinmann and Dia-Compe 750's have even more reach. Those 750's were typically used on rear wheels, though, paired with a shorter 610 up front. If you were to use a 750, you may have to 'borrow' a longer bolt from a 610.

Aha ! Thats a cunning plan . Have tried some weinmann center pulls but not sure which model .
Also some mafac racers stashed away which could be the answer.
cheers

1simplexnut

[QUOTE

Oh, the main why would be clearance for a 27 x 1 1/4 touring tire, as well as a fender, most likely.[/QUOTE]

hiya have added a link to flickr pictures of complete bike . No eyelets for fenders anywhere .
Maybe it was just a mistake ? who knows .
Thanks for your help

1simplexnut

ohhh ok .
Will check that out . fingers crossed thats not the problem

Cheers Chas as always a font of knowledge

noglider 

Your pictures aren't good. Hold the bicycle vertical and shoot with the lens perpendicular to the ground so it's a dead-on shot. We need this so we can see if the fork is bent. That's the first thing that popped into my mind when I read your first post.

1simplexnut

Hi Tom ,

Looked ok by eye when it was assembled . Now completely stripped and have been doing a dry fit of parts before strip and paint.
The fork tips do seem slightly misaligned when I put a wheel in so will investigate further
Will try Verktyg suggestion and see what I come up with .

thanks for the input

1simplexnut

hmmmm wonder if these will fit ?

CliffordK

Why not just use the drop bolt setup that the bike came with (or similar).

You'll be messing around with your leverage, pull, and probably flex in the brake arms if you use some massively long brakes.

Charles Wahl

On the front, you could always have a machinist or frame-builder make an extension that is a more elegant drop solution than the externally-mounted plates: something made of two brazed (or one machined tube) with upper portion inserted into steerer tube, secured at the crown brake bolt, and with its own (lower) brake bolt holes for mounting whatever reach brake you'd like to use. Could be painted to match frame.

unworthy1

that poor thing needs oxalic acid bathing STAT! And rather than strip and repaint (tho obviously that would solve a lot of problems) unless you have access to re-pop decals maybe keep it original and touch up all the rust spots after OA bath.
Not sure about the front-end collision and if that subsequent straightening of forkblades would fully account for the clearance, but it looks like there MIGHT be evidence of such damage so fully investigate. if you could take it to someone with a frame-builder's table and/or precision measuring tools that would be ideal, and they could fix it if it's bent.
Even with the shim looks like the seatlug ears might be pinched or once were deformed, get the set tube measured and buy the proper size seat post.
Looks like a nice frame and worth the effort to bring it back to life.

1simplexnut

hiya . Yes is in the process of getting rust killed etc . Paint is pretty much toasted unfortunately . lots of snail trails underneath paint.

Forks tips are slightly out of alignment axially . HAve carefully checked the frame for crash damage . all good yay!

Have found some info on ishiwata 022 tubing which says the seat tube should be between 26.8 & 27.4 if I am interpreting the info correctly

Wish I had a frame builder nearby . Live five hours drive from nearest city.

Will muddle on . Thanks for the thoughts

1simplexnut

Now thats a darn good idea ! cheers . Do know a friendly engineer who owes me a favour or two

1simplexnut

Hi , had a look at this and seemed to only get about 30mm ? The rake looked comparable to a couple of my Peugeots ( later 80s) but less than a 72 px10
Could it just be the geometry ? These bikes were built to be raced not for touring .
Fork tips are a little misaligned axially . HArd to measure but appears to be about 5mm out.
Could I rectify this with a bit of brute force ?

verktyg 

30mm? Sounds like it's been straightened out a little.

Fork rakes on road racing frames from the 70's through the early 90's ranged from 40mm to 55mm. Track bikes from that era used 25mm to 40mm rakes.

My original suggestion for measuring (guesstimating) the rake on the bike (hard to get exact dimensions):



From the BikeCAD website - easier to do since you probably have the fork out of the frame:




Ishiwata 022 tubing was made of 4130 Chrome Moly steel, the same as Columbus SP and SL. The forks and stays on Ishiwata 022 tubing have wall thicknesses close to Columbus SP tubing while the 3 main tubes are the same as lighter weight Columbus SL.

Can you bend the forks by hand? Yes, but.... The forks are 1.0mm thick. The tensile strength is going to be close to 100k psi. Say you bend one of the fork blades 1/2", that's not enough to "take a set" to permanently stay bent... It will spring back to it's original condition.

You have to figure out how far you need to bend the blade to get it to spring back to the desired change. This is a trial and error operation the may take several attempts. Every time you go past the yield point the steel gets harder and stronger and requires to get it to bend again. It's called work hardening.

It soon becomes a "tar baby"...! Things to consider when realigning a fork:

1. The crown needs to be perpendicular to the steerer (bent steerer?)

2. The fork blades need to be on a parallel plain to the axis of the steerer.

3. The fork ends need to be set to the proper width and parallel to the axis of the steerer and perpendicular to the fork crown.

4. Both fork blades need to have the same curve and rake distance (one cant be more forward or back from the other).

5. A properly trued wheel needs to sit in the fork equidistant from the centerline of the steerer (the same distance away on both sides of the rim from the insides of the blades).


I have a VAR 478 Fork Alignment Gage and a Park FFS-1 Frame Straightening Tool that I can make minor adjustments with.



If a fork is too far out of whack, which many are, I take it to a frame builder friend's shop and pay him to properly align with his jigs and alignment tools. We tried to realign a Reynolds 753 fork once - NO-GO!

A misaligned fork will cause all kinds of handling problems, from pulling to one side to twitchy handling, even shimmy!

I'd recommend that you find someone who has the tools and, KNOWS WHAT THEIR DOING, realign the fork for you, even if you have to send it out to a frame builder.

Good luck....

verktyg

Chas.