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Can anyone point me in the direction of some reasonable off-road in the London area? It's a long time since I MTB'd, and I pretty much just rode around Epping Forest back in the day.

I want to do a decent shakedown of my cross-country bike, which is a hub-geared hard tail. Preferably something with a few reasonable climbs, so I can at least see if I've got a reasonable gearing setup.

The corporate race starts at 6:30. It's some sort of goofy run-to-your bike and do a lap, then tag out. Weird.

Watched that last year and it was a bit odd. The corporate riders had to run with their bikes for a bit, they had to cross some sort of line before they were allowed to get on.

I think MTB SPD pedals would work better than roadie ones - it's only one lap, so you make up loads of time by being able to actually run and then instaclip, rather than skittering around like a foal on an ice rink in roadie shoes. Bonus points if you can do a CX remount.

Yep, that's what I meant Ed. I can see that with the road cranks & 2.1 combo there's going to be a fair bit of fiddling about.

Those chain stays look like they've been set closer to the centre line of the bike than I'd normally expect. Is there a particular reason why?

Cheers guys!

I'm looking at the Busch&Muller lights, but not made a final decision yet. They seem to offer a good balance of performance and price, and have models with standlights so they stay on when you stop at lights etc. Going to mount them on the racks, there are plenty of spots to attach them.

Hahahaha! What a doofus.

I totally didn't notice that in the shots. I've just checked and I appear to have put it on the right way up after adding a pump holder.

Final instalment!

I did a dry-build of the frame once I'd finished the brazing to check that there weren't going to be any assembly problems. With the amount of stuff going on with the mudguards, racks, chain guard etc then there was a chance there would be issues. The only problem in the end was that I somehow sheared a bolt, then broke a screw extractor trying to get it out. A slightly stressful couple of hours, but in the end it was removed with no damage.

You can just about see where I filed the Surly logos off the top of the fork crown in that shot.

The painting and assembly process went pretty smoothly. The drive train is an Alfine 8-speed hub running off a JTek bar end shifter, with matching crank and dynamo hub. Brakes are Ultegra flat-bar levers with TRP Spyre disc brakes. I really like them.

The finishing kit is Velo Orange, and the end of the bar was made safe with the top off a Hendrick's gin bottle. The cork is just the right size to fit snugly inside the bar.

It all seems to work well, the bike's quite nippy given how much stuff is on it, handling is fine with a loaded front rack, and most of all my missus is very happy with the final result.

Five Stars for excellent!

Another great project.

Do you think you need the extra seat tube reinforcing tube? Or is it just a better safe than sorry.

Thanks!

Good question, and for the particular tube I used I think the answer is yes. If you look at tubing specification charts you can use seat tubes that are plain at the saddle end, or ones that are butted, either internally or externally. The butting adds wall thickness, and strength. The Zona tube I used has a wall thickness of 0.6mm. The externally butted one has a wall of 1.2mm. So adding a 0.7 mm wall-thickness sleeve gets me a good slab of reinforcement.

I suspect the non-butted tubes are intended for use with a lug, which would provide the extra strength. The sleeving does the same job, and also allows you to do some aesthetic customisation. It also gives a very slightly wider diameter tube to play with. That helps a smooth tube to tube transition across the fillet.

I'll ask someone with more experience!

Once I was happy with the alignment I brazed up the whole of the frame, and used the normal technique of careful filing and various grades of abrasive paper to shape them.

This is the seat tube cluster. I silver brazed a reinforcing sleeve over the tube itself, you can just see the bottom of it in shot.

Then I cut and shaped the head badge from a piece of stainless steel, the idea being that this was left polished and unpainted. I brazed stainless reinforcing rings onto the top and bottom of the head tube, which you can see in this shot.

And here's how it looked once it was painted. I went for a metallic powder coat, Dark Steel was the name of the finish, with a gloss lacquer over the top.

I'm lucky because I have access to a proper frame-building jig. That holds the tubes steady while you tack them, and also has dummy axles that hold the dropouts in the correct position relative to each other and the stays.

When it comes to the actual full fillet brazes they're done in a regular bike workstand. You need to allow the tubes space for thermal expansion, otherwise you can effectively lock stresses into the tubes.

If your mitres are cut nice and tight, the tacks are well-made, and your heat control is good then the frame tends to stay pretty true. That's checked on an engineer's alignment table. The largest movement I've seen is when you braze the bridges into the chainstays and seat stays, which tends to pull the triangle closed, so you need to spread it by gentle(ish) pulling.

Some builders use slightly over-length dummy axles (so a 137.5mm one for a 135mm backend) to artificially "spring" the backend wider. The idea being that this compensates for the bridges pulling it closer, hopefully leaving you with a perfectly spaced set of dropouts.

The front and back of the bike needed the most thought.

I'd originally considered fabricating the fork myself, but the more I researched, the more I realised that it wasn't going to be straightforward. Steel-bladed disc forks have to withstand an awful lot of stresses, and I wasn't confident about the robustness of what I could make with available materials. In the end I decided to use a Surly Disc Trucker fork, as it had the clearances and look I wanted.

Although there were a couple of options for the rear dropouts, I went for the set in the picture above as they were easy to get hold of and not too expensive. Plus they have built in rack/mudguard mounting points.

The design meant I ended up with a very wide rear on the bike. Alfine hubs run 135mm OLD, then you have thick sliders, and the outer steel mounting plates. All told that gets the back out to about 160-165mm. I needed to bend the chain stays to get them around the 35mm town tyres, then back in and out to get to the correct width without causing heel-strike issues.

The first prototype is in the images below. The original plan was to use straight Zona stays, then heat them to the point where they anneal (go soft), bend them to the right shape and then let them cool.

I mocked the back end up, holding stuff in place with tape to see if it would work.

The answer was "sort of". Bending the stays went alright, but the original choice of a part-sockted BB caused problems. Getting the chainstay ports the right shape & angle wasn't really working. In the end, I changed approach.

The final answer was to use a plain BB sleeve, Columbus Zona Cyclocross bend stays and fillet braze it all together. Once I'd settled on them, I bought a pair of Zona CX bend seat stays in order to get a consistent hourglass look to the back of the bike.

The rear dropouts were brazed into the chainstays. You cut a slot to allow the (shaped) tab to be inserted, then tack them into position with a dot or brazing alloy. After an alignment check you can secure them properly by heating the dropout really well, building a small pool of brazing alloy at the mouth of the chainstay, then using heat and gravity to draw the braze down inside the tube, forming a solid plug that bonds everything nice and strongly.

You can see the final result of that here. The brazing alloy is revealed when you file and shape the joint, giving a flowing transition from dropout to stay.

Trickiest part of the operation is to keep the torch flame off the aluminium dropout while you're brazing it together. You have to have the whole unit assembled with a dummy axle in place to hold everything in alignment. However, that went alright, so I was able to drop the wheel into the back end and check it looked alright.

Once I was happy with that I moved onto fillet brazing the front triangle, chain stays and finally the seat stays.

Hello!

You may remember me from previous threads such as, "I built my own frame then someone stole it," and "How many braze-ons can you attach to a Karate Monkey?"

I've been working away on my next bike, a birthday present for my better half. I've just completed the build, so I thought I'd document the process over a few posts.

The brief I got was to build a bike she could jump onto for trips around town in normal clothes, and that could carry a decent amount of stuff. This wasn't to be "a retro show-pony" (quote). There was a fair amount of thinking, some changes in direction as problems emerged, plus a workshop move part-way through the build. So it took a little longer than planned.

However, the basic pattern for the design was set fairly early on. A porteur-style bike with a practical front rack, full mudguards, chain guard, dynamo lighting, hub gear and disc brakes.

So it was with a happy heart but some small degree of trepidation that I set off on build number two. The process of turning a pile of bits into a thing was ahead of me.

Is it time to link the recipe for a Shooter's Sandwich again? I think it is:

http://www.theguardian.com/lifeandstyle/gallery/2010/apr/07/how-to-make-shooters-sandwich

Cut into slices, you can barter them for coffee, batteries, chocolate, a tow, new legs...

Four chaps in Highgate yesterday afternoon. Looking like they'd been having a good time riding around in the sunshine. I don't know who anyone is, but there was at least one forum cap on display.

Built this commuter for a mate under a grand thanks to discounted TF Wide Open frameset. Parts are: 105 compact groupset; Tektro long drop brakes, cheap/used bars, stem, seatpost and saddle. Novatec hubs on A23 with 28c Ultremo ZX tyres. All under 10kg.

Very nice, and a great value for money build. I presume it'll get mudguards at some point? As a commuter already fitted with long drop calipers you're all set.

It's a gradual change in characteristics that sit on a handling spectrum, but it doesn't take that much change in measurement to move things noticeably.

You're altering two characteristics with changes to the fork length and rake; the head angle (as it's initially set against a presumed fork length), and the trail.

Head Angle http://www.bikecad.ca/taxonomy/term/128
Trail http://www.bikecad.ca/trail

Increasing the rake reduces the trail, which will make the steering feel "lighter" and the bike less stable at speed. For a given frame size, increasing the head angle will make the steering feel "faster." Further complicating things, larger tyres (say 28mm v 23mm) increase trail, making things feel slower.

Your best option would be to get someone to fabricate a set using disc-specific steel fork blades, matching the existing fork geometry.

You old dog, Mike.

Loved it!

Really good to see everyone....that made my day.

The lack of signage, and sometimes spurious crib sheet, added to the camaraderie and fun.

Comedy moment was about ten of us following Skully round a mini-roundabout when he had to bail with mini-Skully. He tried to tell us, but we followed blindly anyway.

My sister is now a total cycling convert and nut. Chapeau ZC.

I happened to be riding just behind your sister as she started the climb on Eliot Bank. She may have said "Oh my poor little legs"

Enjoyed the ride this year, especially the later part. Was good fun running in the 29er, but it's tantamount to cheating when it comes to riding on the cobbled bits.

Obviously I'm not a framebuilder, but it looks to me like you'd simply cut a section out of the seat stay and braze that sucker in.

That's pretty much the process, and I don't think it's that pricy. Matthew at Saffron Frameworks has done it, I think on an All-City of some description. Maybe drop him a line?

Are you able to ride on the hoods with those dirt-drops, or are you in the drops all the time? Looks like a lot of saddle-bar drop to sustain.

Good question, I've tried to get a bar position that gives me options.

My regular road bikes are set up with about 8-9 cm of saddle to bar drop. The saddle to hoods position on the KM puts my hands/back in about the same position as the top of the hoods on my road bike. I ran the bike as a single-speed for a while before going for the renovation to check it was OK.

I've also set the bar up with the top section reasonably flat, so you can ride the hoods on this too. The Woodchipper bar is really flared, so the hoods are about 42cm apart, but in the drops it's more like 50-55cm wide.

Finished up the build yesterday, after a few minor frustrations and a couple of trips out to bike shops.

First up was the fact that the Shimano center lock rotors I'd bought clash on the back of the brake pads in the Avid BB7s. I picked up a centre lock to 6 bolt adapter set from Evans, of all places, and a couple of Avid rotors.

Next was the fact that a lack of barrel adjusters was going to make setting up the calipers and the Alfine hub tricky, so I needed to get them sorted too.

Lastly, the Alfine setup instructions aren't great. There's a nut that you clamp onto the shifter cable, but the measurement described in the install guide is completely wrong, so you need to use trial and error. Fundamentally you want the cable to have no slack when you have the lowest gear selected. Once I'd twigged that then it wasn't too hard. The custom cable run I brazed on works well, so that was worth doing.

Here it is. Not really put it through its paces yet, but I like the ride position and the gearing range is pretty broad. It feels like a really oversized, plushy, cross bike.

For the moment I'm running 33t on the chainset and a 21t Nexus sprocket. The sprocket is dished, so you can run it pushed outwards, which gives a pretty much dead-on chainline.

The Jtek shifter is great, the feel of the shifts is crisp and there's no noticeable lag in the transmission.

Now I've just got to go and get it filthy.

It's taken weeks, but I've got the last part I need to get the full build under way.

Hopefully I can make some progress on the weekend.

Hopefully I will be joining the Fraternity of Offroad Idiocy soon. I've finally found a J-Tek bar end shifter for my hub gear, drop-bar, bouncy-front Karate Monkey.

I am excite.

I'd regard myself as a morning person, but I find turbo training first thing is pretty hard. I did do a session before having much in the way of breakfast once and it was way harder than it should have been. HR was higher for a given output compared to the evening. I'm sure science can explain why.

I've started designing a replacement. New thread?