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1973 French Tandem Resoration Project - Advice?!
#21
(09-16-2012, 02:42 PM)RobAR Wrote:  First Law of Tandem. Never argue with the Stoker.

+1
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#22
On the Mafac Centre pulls:
I have those on my old road bike. Cable pull required is much more than a modern STI (or brifter if you like) delivers, by a factor of, dunno... two (almost). So stick to the original brake levers! The suggested KoolStop salmon pads are great, though I like the three colour version (a bit) better.
What might work is using a travel adapter
http://problemsolversbike.com/products/travel_agents/
though I have not tried that yet on my bike (I should, off road season is approching and going cyclogrossing with bad brakes is... suicidal).
Good luck!
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#23
(09-17-2012, 08:34 AM)Joe_W Wrote:  On the Mafac Centre pulls:
I have those on my old road bike. Cable pull required is much more than a modern STI (or brifter if you like) delivers, by a factor of, dunno... two (almost). So stick to the original brake levers! The suggested KoolStop salmon pads are great, though I like the three colour version (a bit) better.
What might work is using a travel adapter
http://problemsolversbike.com/products/travel_agents/
though I have not tried that yet on my bike (I should, off road season is approching and going cyclogrossing with bad brakes is... suicidal).
Good luck!
This is a very interesting point that you raise, Joe.
Can I ask what size wheels you have on your "old road bike"? If we shrink down to 700c, then the brake blocks will have to each be 4mm closer to the pivot, which ought to increase mechanical advantage, but also increase the cable pul required for the same movement. (I've only just thought of this now, by the way) - If you also 'modernised' the wheels, this would certainly explain why you have cable pull problems with STI's.
I'm afraid I'm likely to ignore your advice to keep the current levers, as they're really uncomfortable, and don't allow access to the brakes from 'the tops', which can be a little unnerving. A switch to 'aero' levers is definitely on the cards.
We won't have brifters, due to monetary constraints, which leaves us rather more choice in terms of cable pull options. I was expecting to get THESE Tektro's, which are described as having "More clearance for caliper brake arms to open". Do you think this will be sufficient? Since having the thoughts about wheel sizes above, perhaps the sensible alternative may be to opt instead for THESE Dia-Compe's, which have been designed with a V-Brake cable pull ratio, and therefore should pull more than enough cable through, at the expense of the mechanical advantage, which is as I say, somewhat compensated for?
Re: KoolStop compound, What is it about the 3-colour that you like specifically? Since we're very likely to be mostly fair-weather tandemists, (excepting rain on organised (summer) outings like the London to Brighton) is it not sensible to get the standard 'Black' ones? They're slightly cheaper, and, I've heard they'll last longer, if used only in the dry, when compared to the salmons?
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#24
Also, Does anybody have any theories (crazy, or otherwise) regarding the mystery of the BB cup stamping? I've not heard anything from anyone regarding this, and I'm confused :S
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#25
The bike is a probably 1978-ish French road bike (Mafac Competition with soldered on brake bosses, others had some mounting plates), the fork is older (judging from the numbers scrawled on it). Since it has been repainted and frankenbiked it is impossible to really tell (for me). The wheels I got it with were standard 700c (with a Maillard Helicomatic hub). The brakes did work fine with the original brake levers, but since I changed to STI-style levers they... suck. a lot. dangerously so. They would be outright dangerous / suicidal on a tandem (higher speed and mass).
My suggestion would be to measure the cable pull of the old brakes and then decide on the lever. My guess would be leaning towards getting the DiaCompes.

Brake pads: The salmon rubber mixture is very soft and optimal for rain. It also wears away comparatively fast. The tri-coloured option offers a harder leading edge to (in theory) clear away some of the grime and a normal and the salmon compound. I like the story behind them. They work well enough on my modern road bike. The old road bike has the salmon ones, it is used mainly in winter and off-road (cross duathlons and such). While abhorring rain on the road I enjoy riding in the rain vertical rivers. With the old brake levers the salmon coloured pads worked very well.

---
Edit: I'm glad we're having the brake / lever discussion, I have been meaning to ask about that but wanted to take pictures first...
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#26
(09-18-2012, 06:51 AM)Joe_W Wrote:  My suggestion would be to measure the cable pull of the old brakes and then decide on the lever. My guess would be leaning towards getting the DiaCompes.
In it's current state, with 27" wheels, I had to set up the brakes (for the London to Brighton) with quite a lot of 'free movement' before the pads engaged, to allow me to 'half squeeze' the levers whilst traveling, in order to hold my fingers on them, to be ready for an emergency. When on the tops you had no chance, and on the drops, you can't normally reach without a real stretch! If indeed the cable pull required does increase, then I would be unable to set it up in this manner, meaning that even if the levers worked, I'd never be able to use them! (without first planning to do so).

I've also had another (potential) brainwave: I believe that, while the amount of cable pulled per degree that the lever pivots is a factor (and it is this that I suspect it different about the Dia-Compe's), often it is the lever bumping into the handlebar that stops the travel of the blocks prematurely. If one were to mount the levers slightly further up around the bars than usual, slightly on the bend, then they would tilt back, leaving lots more room for the levers to swing back. Depending on the design of your bars/hoods, you could then tilt the bars down a bit, meaning that 'on the hoods' has your hands at a similar angle, and 'on the drops', you just slide a bit further around the curve?

Obviously it'd make sense for me to get some with a sensible pull ratio to avoid this, but it might be worth you giving it a try.

On a side note, I've had quite a few opinions regarding the Travel Agents, (before I realised my bosses were too close together, I had considered V-Brakes), and the consensus seems to me (if you trust my aggregation) that they work very well, functionally, but do accelerate cabe wear and introduce friction losses into the system, thereby (maybe) costing you more than replacement levers in the (very) long run.
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#27
(09-18-2012, 08:00 AM)pargeterw Wrote:  In it's current state, with 27" wheels, I had to set up the brakes (for the London to Brighton) with quite a lot of 'free movement' before the pads engaged, to allow me to 'half squeeze' the levers whilst traveling, in order to hold my fingers on them, to be ready for an emergency. When on the tops you had no chance, and on the drops, you can't normally reach without a real stretch! If indeed the cable pull required does increase, then I would be unable to set it up in this manner, meaning that even if the levers worked, I'd never be able to use them! (without first planning to do so).

That sounds a bit like your hands are too small for the setup? Can you apply maximum stopping power this way? Actually thinking of it: My old setup also had a bit of travel before the pads engaged (mud clearance). Now the pads are really close to the rim...

Quote:I've also had another (potential) brainwave: I believe that, while the amount of cable pulled per degree that the lever pivots is a factor (and it is this that I suspect it different about the Dia-Compe's), often it is the lever bumping into the handlebar that stops the travel of the blocks prematurely. If one were to mount the levers slightly further up around the bars than usual, slightly on the bend, then they would tilt back, leaving lots more room for the levers to swing back. Depending on the design of your bars/hoods, you could then tilt the bars down a bit, meaning that 'on the hoods' has your hands at a similar angle, and 'on the drops', you just slide a bit further around the curve?

Obviously it'd make sense for me to get some with a sensible pull ratio to avoid this, but it might be worth you giving it a try.

Most likely not doable in my case. They are more than high enough already and the old road handlebars have quite a tight bend. So, yes, while in principle they could provide the needed amount of cable pull if the handle bar wasn't there, they cannot be made to work here. I'll take a look at that and keep you posted.
But yes, it is the cable pull per lever rotation that is the factor. There's just no way in getting the required travel out of modern levers. A factor of (roughly) two in linear pull means (roughly) twice the rotation angle (actually more when you really think about the geometry).

Quote:On a side note, I've had quite a few opinions regarding the Travel Agents, (before I realised my bosses were too close together, I had considered V-Brakes), and the consensus seems to me (if you trust my aggregation) that they work very well, functionally, but do accelerate cabe wear and introduce friction losses into the system, thereby (maybe) costing you more than replacement levers in the (very) long run.

As there are no STI levers that are V-brake compatible (to my knowledge) I guess I have give them a try unless other options present themselves (= buying another bike).
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#28
(09-18-2012, 09:21 AM)Joe_W Wrote:  That sounds a bit like your hands are too small for the setup? Can you apply maximum stopping power this way?
I'm absolutely sure my hands are too small for the setup, but only because the levers are too far out by design. are anybodies hands big enough to reach these from the drops? [Image: jLfBV2OstbMHe_e.jpg]

(09-18-2012, 09:21 AM)Joe_W Wrote:  unless other options present themselves...
Or you could lop the bottom off the STI's with a hacksaw, allowing them to pivot further? : P
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#29
Somewhat predictably, because I said my last blog post would likely be the final one for a while, I've only gone and written another bloomin' blog post!

This one is an investigation into the Mystery British Cups, and the damage that they have caused (if any), and the possible courses of action. I'd really appreciate some opinions on this one!

Sorry to keep battering you with words like this! Thanks for your patience, and help.

Will
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#30
Ouch, yeah, that's a looong distance. I guess you need to be about 2m tall to have hands big enough. Think of basketball players' hands. Plus: look at the fork crown, really nice! Congrats and good luck on your journey.

My understanding of threads and what is safe and what's not is a bit shaky, probably our resident engineers will want to chip in on that. As far as I understand the blog post you had BSA cups in a French threaded BB shell (though... weren't those threaded the same on both sides?). This is bad. Some threads are damaged, though it seems to be hard to tell how badly and if some ham-fisted, bug-brained bad excuse for a mechanic tried to "fix" the threads by chasing them with a thread cutter. If they have been re-cut then you have a problem: There's likely not enough meat left for the cups to hold. If the old cups just have been forced in (and didn't manage to go in really deep) then the correct ones might still stick as there could be enough thread left (beginning and end). Forcing the (essentially) self-cross-threading wring cups in and praying to $deity that they stay in place sure is an option. It will likely work well enough, but I cringe at the thought of it.
There is a clean solution: have the BB shell faced for a repair (threadless, expanding) BB. There are some options out there. They are all expensive but may be the best hope if all else fails.
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#31
Based on what Joe wrote - because I am still in China for another 16 hours, and can't access your blog - we are going to need close up pictures to provide an assessment.

Found these - not as expensive as I feared:
http://www.sjscycles.co.uk/prestine-threadless-68mm-sealed-bearing-bottom-bracket-for-frames-with-damaged-threads-prod16505/
http://store.velo-orange.com/index.php/grand-cru-threadless-bottom-brackets.html
Nigel
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#32
(09-19-2012, 09:42 AM)nfmisso Wrote:  Based on what Joe wrote - because I am still in China for another 16 hours, and can't access your blog - we are going to need close up pictures to provide an assessment.

Fortunately, I have taken many close up pictures! I wonder if you can get at the PHOTO ALBUM from where you are? Even if you can, I'd probably wait until you've read the actual post before forming any opinions, since it explains quite a lot of things that you might not guess...
(09-19-2012, 07:05 AM)Joe_W Wrote:  As far as I understand the blog post you had BSA cups in a French threaded BB shell (though... weren't those threaded the same on both sides?).
It is only the adjustable cups that are BSA, hence the differing threads in the first photo.

(09-19-2012, 07:05 AM)Joe_W Wrote:  if some ham-fisted, bug-brained bad excuse for a mechanic tried to "fix" the threads by chasing them with a thread cutter.
I'm pretty sure that this has not happened, as, since you rightly pointed out there would be some turns missing entirely.

(09-19-2012, 07:05 AM)Joe_W Wrote:  If the old cups just have been forced in (and didn't manage to go in really deep)
This is my diagnosis, at least. I'm hoping I'll be able to find two adjustable french cups (with lockrings) from somewhere (might try the 'wanted' page on CTC forum). These should thread in further (since they have thinner walls) and push past into the undamaged thread, for extra strength. Also, nice and cheap.

(09-19-2012, 07:05 AM)Joe_W Wrote:  There is a clean solution: have the BB shell faced for a repair (threadless, expanding) BB. There are some options out there. They are all expensive but may be the best hope if all else fails.
I've not heard good reviews regarding the long-term reliability of these threadless systems, so putting one in the rear, where it takes twice the stress of a single worries me somewhat. But, if all else fails!
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#33
pargeterw on his blog Wrote:The O.L.N. of the rear dropouts (which many people have asked me about) is 130mm, although there is an extra 5mm added by the supplementary deraileur hanger. (difficult to show in a photo due to the rounded edges!)
The distance you want to measure is the OLD (over locknut distance), which is the distance between the insides of the drop outs, so the dérailleur hanger does not matter...

Cold setting: I'd avoid it if you had to spread the frame more than, say 5mm in total. (I think this has been said by Nigel before...)

BBs: I thought about it for a moment, I guess you might be right about the increased "stress" on the rear BB. Looking at the points of attack of the two force vectors (sync chain and drive chain), there is definitely a resulting torque on the bottom bracket. It is (almost) perpendicular to the maximum load from the pedals, so the result should be... dunno... 1.5 times as big (peak torque)? I'm too lazy to actually draw it at the moment and do the geometry.
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#34
(09-19-2012, 01:24 PM)Joe_W Wrote:  The distance you want to measure is the OLD (over locknut distance), which is the distance between the insides of the drop outs, so the dérailleur hanger does not matter...
In my case OLN stood for Over LockNuts, but, you're right I was measuring the wrong thing, and have been made aware of this already. I was seduced by how perfectly it measured 130mm on the outside, I think!
The actual value is 124mm, so I'll have to expand by 11mm minimum in order to get in THIS hub, and it'd be 21mm for the SHIMANO. I've spoken to people with Peugout tandems who've done this successfully, and without issue, but it's more than I'd be comfortable with (and, I don't think I can afford that anyway).
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#35
Back home Smile and I can access the blog Smile

Rear BB - I would put the cups you took out back in - they fit okay. Do anything else will likely further damage the frame; probably to the point of requiring replacement.

Front BB, you could get a replacement eccentric with the properly sized BB; but I would not - I would put the cups back in that you took out.

The BB axles look fine. Get new balls; a good grease - I use grease intended for boat trailer wheel bearings; which is a much tougher environment than a bike, and will last decades in a bike BB. Over fill the grease, so that it squeezes out when you tighten the cup; which will prevent water and other undesireable things from getting in there.

Headsets - swapping to loose balls - sometimes it is a PIA; sometimes it is very easy, depending on how well the races are protected from the outside world. My SR and 310 were easy; on the GT, I gave up and went back to caged bearings. The SR actually has loose on the bottom and caged on top because I did not have enough balls to both loose. The bottom should have more balls because it supports the preload and gravity loads, where as the top just has the preload. Again, use new balls and a generous amount of boat trailer wheel bearing grease.

124mm OLD - tough one. Go to your local hardware/DIY center, and purchase a 200mm or longer piece of M10x1 threaded rod and at least six nuts (jam nuts are okay) to fit the rod. Set up the rod with four nuts to simulate a 135mm OLD hub, and try installing in your frame as is. Some frames have enough give that this will work with no cold setting. Also try 130mm.

I would not attempt to go past 135mm with your frame. I would also seriously consider going with 130mm and dropping the rear drum brake entirely. Modern rims like Dyad and CR18 have a lot more thermal mass (heat up slower) than your original rims, and the aluminum is a far more effective braking surface than steel.

The vast majority of the hills in the UK are not long and steep enough to require a drag brake, and the few that are, just take it easy; alternating between the front and rear brakes to allow the rims to cool. If you are planning on riding the Alps or Rockies - get a different tandem - you'll want something stronger and lighter for pushing up those grades anyway.

V-brakes - I woukd try fitting them, even though the bosses are "too close" together. V-brakes are usually set up with thick spacers on the inside of the pads, which are intended for angular adjustment of the pads. They can be removed, and if needed you can file a much thinner brass or stainless steel washer to do the same function.

Alternately, will dual pivot side pull brakes work - more expensive, and the fork and frame need to have Ø6mm holes for mounting them. Are the fender mounting holes Ø6mm? If yes - to me it is a no brainer - go with Tektro R536/539/556/559 nutted versions (as opposed to recessed nuts). The xx6 and xx9 are just different finishes, the 53x and 55x have different reaches - see Sheldon.

Get some cross levers to go with the STI levers, (and travel agents if you decide to go V-brakes).
Nigel
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#36
(09-22-2012, 04:54 AM)nfmisso Wrote:  V-brakes - I woukd try fitting them, even though the bosses are "too close" together. V-brakes are usually set up with thick spacers on the inside of the pads, which are intended for angular adjustment of the pads. They can be removed, and if needed you can file a much thinner brass or stainless steel washer to do the same function.

Alternately, will dual pivot side pull brakes work - more expensive, and the fork and frame need to have Ø6mm holes for mounting them. Are the fender mounting holes Ø6mm? If yes - to me it is a no brainer - go with Tektro R536/539/556/559 nutted versions (as opposed to recessed nuts). The xx6 and xx9 are just different finishes, the 53x and 55x have different reaches - see Sheldon.

Get some cross levers to go with the STI levers, (and travel agents if you decide to go V-brakes).

Actually it is not possible to get away from the Mafac Competitions if the brake bosses are soldered to the frame except by replacing the fork and resoldering V-brake bosses to the rear. The brake bosses of V-brakes and Cantis sit below the rim. The brake bosses of Mafac Competitions sit above the rim. They are more like U-brakes that were popular on MTBs in the early 90s (or so). Another possibility is removing the brake bosses and soldering a new bridge between the seat stays to accept a modern road bike style brake, preferably with long brake arms to be able to install wider tyres, but I personally would not do that.
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#37
(09-22-2012, 04:54 AM)nfmisso Wrote:  ...Boat trailer wheel grease...
Thanks for the recommendation, I'll look for some of this

(09-22-2012, 04:54 AM)nfmisso Wrote:  124mm OLD - tough one. Go to your local hardware/DIY center, and purchase a 200mm or longer piece of M10x1 threaded rod and at least six nuts...
This has possibly given me an idea: long threaded rod, with flat blocks of wood on either side of the dropouts holding them parallel, and then, alternating sides, loosen the outer nut on one side by half a turn, and tighten the inner nut on the same side (re-clamping the dropout between the bits of wood). I know I'd have to keep loosening this off completely to re-measure, as the frame would spring back a bit, but it strikes me as a very controlled method of stretching the frame, which simultaneously keeps the dropouts in parallel automatically? Perhaps I should test this on a scrap frame first...

(09-22-2012, 04:54 AM)nfmisso Wrote:  Alternately, will dual pivot side pull brakes work - more expensive, and the fork and frame need to have Ø6mm holes for mounting them. Are the fender mounting holes Ø6mm?
Sadly, I've left for University already, so can't pop out and measure this. My father has the tools, but lacks the athleticism to retrieve the frame and bits from where I left them up in the roof of the garage!
(09-25-2012, 07:22 AM)Joe_W Wrote:  Actually it is not possible to get away from the Mafac Competitions if the brake bosses are soldered to the frame except by replacing the fork and resoldering V-brake bosses to the rear. The brake bosses of V-brakes and Cantis sit below the rim. The brake bosses of Mafac Competitions sit above the rim. They are more like U-brakes that were popular on MTBs in the early 90s (or so). Another possibility is removing the brake bosses and soldering a new bridge between the seat stays to accept a modern road bike style brake, preferably with long brake arms to be able to install wider tyres, but I personally would not do that.
Take a look here, It seems to me that the bosses are below the rims? Perhaps these are not "Competitions"? Either way, when I switch down to 700c wheels, they will be very close to the rims, and I feel inclined to stick with what I have (+KoolStops) until a problem presents itself![Image: jxYTcdefeUlWD.JPG]
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#38
based on your picture - I would try fitting V-brakes. It appears the pivots are about 25-35mm below the braking surface on the rim.
Nigel
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#39
Yes, it is definitely not Mafac Competitions. They are (early) cantilever style breaks, I'd say. So: yeah, everything is fine and you should be able to fit V-brakes as Nigel suggested. They are much easier to set up (I find) and have good stopping power. Sorry, I did not want to cause any confusion!
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