Frameset transplant: Spa Titanium Touring

[pwa]

...Rack mounts feature M6 threads, which seem far more appropriate than M5 - why don't all rack-capable frame designers specify this?..

M5 bolts are stronger than you might think. Strong enough to carry the weight of anything you might reasonably put on the back of a bike.

I think they are up to the job so long as the weight of the rack is on the portion of the bolt that is right next to the dropout. It is when you introduce spacers and have the weight further out from the dropout that you risk things going wrong.

My Club Tour was an early one with M5s and I never had a bolt failure there.

[Foghat]

Just a thought but are you certain that you actually have the long spacers fitted?

The long spacers on my BR-CX70's measure 18mm. There's an additional 2mm available depending on where you place the 2mm thick washer. With this combination you ought to be able to accommodate 85mm boss spacing with 19mm rims.

Thanks for the suggestion, but yes I am definitely using the longest spacers - I bought the brakes new and they came with all three length options.

You're right to raise the 2mm spacer too. Unfortunately, with the bosses so much higher than they should be, when I put the spacer on the rim side of the cantilever arm, the blocks unavoidably rub the tyre (which is only 32mm)....and I can't get the shoes any lower because the damned things are already at the bottom of the slots! The double whammy of too wide and much too high is ridiculous.

I suppose I could try shaving the top edges of the blocks off in an attempt to clear the tyre. Or I could try filing/cutting the slots lower, but I've had enough of having to do that on some other (dual-pivot braked) bikes for now. Although if the constant rear brake monitoring/adjusting and wheel fine trueness checking/correcting starts brassing me off much more than it does already, then I may try that too. My main focus is to get the new disc-braked commuter into service, so all the rear cantilever nonsense with the Spa becomes less of a constant issue...albeit replaced by brakes with other kinds of maintenance demands.

[Foghat]

Sorry to hear of your problems. I took my frame to a LBS to have the headset fitted and the bloke and I both looked at the head tube ends and could see that it had been machined and appeared good. He later said it all seemed fine, the headset assembled perfectly and the steering is faultless. The canti brakes (Tektro) went on without an issue and I was able to move the blocks up and down to choose which part of the rim to use, so again I think mine is fine in that regard. The drop outs do have decorative / weight saving cut outs that could constitute a weakness, but I don't feel too worried about that at the moment.

Maybe mine's a one-off, but good to hear yours isn't similarly afflicted. Hope you have plenty of good miles and riding with it!

[pwa]

Sorry to hear of your problems. I took my frame to a LBS to have the headset fitted and the bloke and I both looked at the head tube ends and could see that it had been machined and appeared good. He later said it all seemed fine, the headset assembled perfectly and the steering is faultless. The canti brakes (Tektro) went on without an issue and I was able to move the blocks up and down to choose which part of the rim to use, so again I think mine is fine in that regard. The drop outs do have decorative / weight saving cut outs that could constitute a weakness, but I don't feel too worried about that at the moment.

Maybe mine's a one-off, but good to hear yours isn't similarly afflicted. Hope you have plenty of good miles and riding with it!

It is a pain, I know, but if your brake bosses are well out of spec you ought to ask for a replacement frame because that will cause you maintenance issues.

[Foghat]

I think they are up to the job so long as the weight of the rack is on the portion of the bolt that is right next to the dropout. It is when you introduce spacers and have the weight further out from the dropout that you risk things going wrong.

Agreed.

My question is less "are M5 up to the job" than "why the reluctance among frame designers to specify the almost failsafe M6 when the rack may be used for heavy loads and/or on rough terrain and will have a fairly high probability of being one requiring leg spacers".

Pleasing to see that Spa seems to specify M6 (at seatstays and dropouts) on some (most/all?) of its touring frames.

[fastpedaller]

Yes indeed the M6 are a good inclusion. From what I've read in recent months the quality of the Spa frames seems to have slipped since I bought mine in 2014 - Do we know if the manufacturer has changed?

[Brucey]

in fairness M6 is certainly stronger but in extremis something is going to break; the bolt, the carrier or the frameset. If it ends up being the last of these it is something of a disappointment, to say the least. Some frames are not built strong enough to withstand a good size knock even with an M5 screw fitted; for example I have seen the relevant part of a rear dropout break off clean on a Dawes Audax, when a rack was fitted to it.

cheers

[pwa]

With aluminium frames I avoid relying on the frame's threads when installing a rack. It is too easy to strip them. I go for a slightly longer bolt and put a nice steel nut on the far side. But apart from that I don't have many problems with rack eyes, or the bolts. M5 or M6.

[Foghat]

So would the CEO and Head of Design at Brucey Bikes plc prefer to sell bikes with M5 or M6 rack mounts (or something else).....or would it depend on application?

[Brucey]

depends on the application I suppose. Not every rack will readily accept a 6mm bolt, but the strongest ones do. FWIW I put bolts through from the inside (if I can do, sometimes this means making a special bolt) even in steel frames. Nylock nuts and washers of course to finish, I also carry spare bolts in my touring load.

FWIW racks can usually be repaired well enough to last a few hundred miles (using various bodge-tastic methods) but it is obviously far better if they don't break to start with. Broken bolts ought to be easy to deal with, but they have an annoying habit of breaking off flush (so there is nothing to get hold of) or getting bent so that they won't unscrew easily.

FWIW I have always kept loads sensible, bolts tight and have not suffered problems. But I've seen others who have and some things that are to be avoided are;

- racks that fit by being horribly strained into position; it is a far better idea to cold set them to fit if necessary
- racks that are mounted with too many spacers and worse yet those spacers are small diameter and/or swivel easily
- rack bolts that also hold things that are squashy, such as Berthoud stay clips or Secu-Clips; these can't be tightened fully and also settle in use.
- bolts that are not tight. When touring it isn't a bad idea to check the critical rack bolts every day; if they are in the slightest bit not tight enough, you can get a nasty hammering load passing through the bolt that is very likely to break something.

V-brake spacers look idea for spacing racks out, and they work OK right up until the moment the bolt loosens slightly, when they suddenly allow swivelling and put a horrible bending fatigue load into the bolt. Spacers, if you must use them, should be solid and of as large diameter as you can sensibly fit in the mounting.

A common cause of bolt loosening is that the paint is thick and gradually gets squeezed out of a bolted joint. If you only have one eye to work with, it is best to bolt the rack to the frame and the mudguard stays to the rack (eg using small P clips). If you are not carrying a huge load then it is OK to have the rack leg against the frame and the stays outside of that (this reduces the bending load on the bolt).

cheers

[pwa]

The weather today has been good, with sunshine and mild temperatures, so I took the bike out for a nice 15 mile spin. I expected to have to do the odd tweak on the way round but I had no mechanical issues at all. And the bike behaved just as I would want it to. Steering seemed completely natural, so that I didn't have to think about it. At one point, on a very narrow lane with a steep camber, deep longitudinal cracks in the tarmac and a van waiting for me to pass, I picked my way through delicately at low speed with no hint of a wobble. I even managed to raise a hand of thanks to the driver. And 30mph descents felt rock solid. Faultless handling.

The Jtek seatpost shows no sign of slipping, even with all the anti-seize grease I smeared over it. I'm close to declaring it a non-worry, but I will do that when it has done a 30 mile ride. It still has the strip of insulation tape 1mm from where the post disappears into the seatube at the clamp, and the gap hasn't changed. The post also seems to be holding the saddle at the chosen angle.

[531colin]

Blimey, its been freezing here.
"No mechanical issues" is down to your assembly....chapeau!
I like your description of the handling, thats just how I want a bike to handle; unperturbed by camber or surface imperfections. Stable when descending with enthusiasm.

[Foghat]

Agree with all of that, Brucey.

I find it irritating that frame designers increasingly seem to think single combined rack/mudguard stay holes (invariably just M5) are the optimum design, instead of dual dedicated holes (for which my preference would be the same as Spa specifies, namely M6 rack + M5 mudguard).

[horizon]

https://forum.cyclinguk.org/download/file.php?mode=view&id=64963


There are still a few small things to tidy up. I can think of one you might have spotted but I won't spoil it by pointing it out.

Silvery coloured bottle cages?

No, I'm not fussy about things like that.

Absolutely. This has been a great thread because IMV it reflects a philosophy (if the OP will allow):

1. Keep the bike simple.
2. Keep the bike practical.
3. Don't worry too much about looks.
4. Use old parts where appropriate
5. Concentrate on good building practice rather than new technology.
6. Use well tried and cheaply available components.

The bike, its use, its potential, its low cost, its repairability are all within your personal domain as far as can be achieved. You won't find this reflected in Cycling Plus etc etc. This is the hidden philosophy of the bike and life in general.

Hats off and thanks to pwa not only for describing the build but sticking to his guns. Great!

[pwa]

Just a quick update.

As well as testing my new GPS thingy today I was tweaking the bike. It now has a new axle assembly on the rear wheel (axle, cones, bearings) and a 34t largest sprocket to replace the old 32t. The b screw needed going in a bit to get the mech to clear the big sprocket.

One thing I've noticed on a few rides now is that I have got off to feel the tyre pressure due to the ride feeling too smooth. I didn't get that with the same tyres and wheels on the old steel frame so, much to my surprise, I think there might be something in the idea that titanium can give a silky ride. Either that or my Cambium saddle has decided to yield a bit more. I'd better look closely at that in case it is breaking in some way. It isn't making any strange noises though.