Tag Archives: Bikes

Bicycle frame jigs (1/4)

There are a handful of approaches to design a bicycle frame fixture. Taking advantage of Henry James knowledge from his website and my own researches I have ended up with this article about the existing possibilities. A lot of information spread all over the bike forums that somehow I wanted to gather and analyze.

Holland custom frame in an Anvil fixture.

Holland custom frame in an Anvil fixture

Jigs can be classified according to different criterias: professional solutions vs. hobbyists fixtures, horizontal configurations vs. vertical mountings, tack-only vs. fully weld frame jigs, mass-oriented production jigs vs. custom frame geometry units, beam inspired types vs. beamless jig designs, multipurpose and extensible jigs vs. simplified versions, the place where you start to assemble the tubes on the jig and so on.

Professional fixtures will provide full access to each joint for TIG welded and fillet brazed construction without the hassle of tacking and removing the frame in order to fully weld it apart. At the same time is easy to remove and replace the frame during the assembly process, especially important when using lugged construction or when we want the gravity to assist the welds, which is a good thing.

Jigs having vertical structural plates and/or members are superior to horizontal or backbone based models. Their individual clamping components are shorter, located closer to the joints and connections, hence stiffer than the same type of fixture that has to extend all the up from the base plate.

Homemade tack-only jigs are affordable if you are planning to build just lugged bicycle frames. Roomier units that provide enough clearance to fully weld the frame vertically on the jig can be achieved with DIY beam designs at the expense of more complexity when determining, for example, the BB drop as it will be “floating out in space”.

Pure beam style jigs for mass production (the ones used in BMX companies for example) have limited range of adjustment but work well and offer a lot of access for peanuts. On the other hand, jigs that combine compact plates and adjustable arms via extensions that hold the “bearing areas” (BB, HT and rear axle) generate almost endless geometry combinations with good clearance.

Fixtures made of beams are very rigid and provide great accuracy if we go for extruded aluminium profiles and machined parts. On the downside, aluminium can be considered a bit expensive compared to wood or traditional metallic square profiles.

A multipurpose jig will meet more framebuilders needs, for example integrating a fork building feature in the rear axle frame fixture, or offering motorcycle jig capabilities.

Finally choose the jig that makes the tubing logic assembly fancier for you. Building from the BB up is a better alternative in my opinion.

Here is a brief summary of the frame jig types according to their design:

No jig. This goes back a hundred years. Accuracy depends on craftsmanship, not tooling. Because no fixture is used, lugged joints often are pinned together by driving nails tightly into drilled holes in every joint. This holds the frame together, and hopefully keeps it in place during brazing.

Welding bicycle frames in an American factory (not named). Wood engraving Leipzig 1900.

Welding bicycles frames in an American factory in 1900

Flat surface. The frame is assembled on a flat plate which is larger than the frame, and made of granite, cast iron (steel) or aluminum, or for beginners, particle board or plywood. Fixtures consists of shims, vee blocks, or other holders that locate the tubes on the center line of the frame. Setup takes forever, and access is limited. Used for tacking only. A good choice for building your first frame considering a flat surface is also needed to check the alignment.

A flat surface, machined fixtures and a full size drawing is enough for precise framebuilding

Modified flat plate or vertical plate jig. Still intended only for tacking, The plate is shaped specifically for a range of common frame configurations in an attempt to provide better access. It has specially designed holders for head tube, rear axle, etc. but still with limited capabilities. Because intersecting tubes (HT and BB) and rear axle are clamped it can be mounted vertically.

A massive flat plate design that has been tailored to extreme dimensions

A massive flat plate design that has been tailored to extreme dimensions

Parallel beams jig. Here the plate is replaced with beams that are parallel to the head tube and seat tube. These beams rest on one or two cross beams that are intended to keep the structure flat. This style of jig is very sensitive to warping of the beams. Most beam materials are not inherently dimensionally stable, so internal stresses and external stresses from torch heat, etc., can lead to a loss of accuracy.

To use this style of jig you move and rotate the beams to set the jig up. The problem is that the beams are parallel to the tubes, limiting access just like the plate jigs. The net result is still a tacking jig without the simplicity of the plate jigs, or the access of the compact plate jigs.

The resulting jig is lighter and more portable than a flat plate design

The resulting jig is lighter and more portable than any flat plate design

Compact plate jig. On a compact plate jig, the plate is much smaller than the main triangle. Adjustable arms extend out to support the head tube, BB shell, and rear axle. Carefully designed, offers the best combination of clearance, rigidity, fast accurate set-up and versatility.

Because of the compact design, these jigs can be much lighter than other jigs, making it much easier to rotate the jig as you weld, and the jig takes up much less space in the shop.

Sputnik and Henry James professional frame fixture are ample proof of this design.

A rare variation of this style uses no plate at all, just a bunch of arms that support critical parts of the frame. Both Anvil and Bringheli jigs implement this design.

Sputnik stands out as one of the best choices

Sputnik stands out as one of the best choices

Bottom up or backbone jig. A narrow (4″-6″ wide) four foot long bar or beam is the base of this style of jig. The frame sits upright on this base. Along the base are supports for the BB shell, rear axle, and head tube. Additional supports may be added to hold the seat, top and down tubes.

Only the axle and BB shell which are close to the base are accurately held. All the other supports extend a relatively long distance from a very narrow base, so errors and tolerances are magnified. Set up is usually slow.

An almost jigless version of a frame fixture can be achieved thru this design. The method is proposed here following famous Paterek instructions.

The main disadvantage on this is that you never see the complete picture of the frame until you tack in the last tube. You can't set it up and then have a sanity check where you can see if it all makes sense

The main disadvantage on this is that you never see the complete picture of the frame until you tack in the last tube. You can’t set it up and then have a sanity check where you can see if it all makes sense

External jig or motorcycle jigs. A rectangular framework structure is sized so that the bike frame fits completely inside the structure. For this reason, these are sometimes referred to as “picture frame” jigs.

A foundation of a wide rail, multiple rails or table are built upwards with the jig fixtures supported from below. Arms extend inwards to support the head tube, BB shell, axle, and seat tube. Because the framework must be the largest of any style of jig, and because the framework members must be heavier to provide the stiffness this large size structure requires, these jigs are heavy and expensive. The inherent problem with this style is that the largest frame you can build is limited by the size of the framework. And, if you make the framework really large, the extensions that hold the bike frames must reach in much farther to build very small frames.

It is stable by itself without the need of mounting platforms.

A variation is a hybrid jig with a smaller framework offset to the rear with extension arms for the axle and/or head tube.

Supacustom bicycle and motorcycle frame jig

Supacustom bicycle and motorcycle frame jig


Park Tool pin spanners and three newsworthy repairs you can do with them

One of my favorite bicycle wrenches are Park Tool pin/peg spanners. It’s because they are handy, strong, cheap and simple tools but also because of the different coloured grips that break the monotony of any tool wall display.


Spanners are made of hardened carbon steel to ensure long life while the handle is vinyl coated

My own experience tells me they are not on a daily basis tools anymore, but still esential for any all-round workshop that services freewheels or old fashioned bottom brackets for example.

The green handled SPA-1 fits the adjusting cup on many old three pieces cranksets. The pin ends are round with a diameter of 2.9mm.

The most popular repair you can tackle is a cup and cone type bottom bracket service.

Mural Park Tool SPA-1

Wherever there are two holes with the right size the Park Tool hanger cup pin spanner will allow you to do different repairs. Adjust the tension of the chain by turning the eccentric BB, removing a dustcup and so on

On the other hand, the SPA-2 red spanner has 2.3mm pin diameter. Due to its smaller size fits better a wider range of hole widths. It releases retaining rings on Shimano and Campagnolo crank bolts and the adjusting cone on most freewheel clusters.

A very interesting repair suitable with this tool is the removal of certain type of non-serviceable freewheels that don´t have an extraction tool option. A freewheel destructive removal method will require this spanner to get rid of the lockring.

The Park Tool cluster cone pin spanner is ideal for several repairs where a lockring needs to be removed, on self extracting or one-key release crank bolt systems or even if you need to fit/extract the guides of the BB facing tool inside the frame

The Park Tool cluster cone pin spanner is ideal for several repairs where a lockring needs to be removed, on self extracting or one-key release crank bolt systems or even if you need to fit/extract the guides of the BB facing tool inside the frame

The third and last peg spanner I own is the discontinued yellow SPA-4. It has a flat section designed to uncrew the adjusting cone of one-piece cranks. This is virtually the only repair you can do with this tool, the service of entry level cranksets on BMX’s and department store bikes.

The tool engages two notches of the adjustable left bearing cone. Rare cup and lockring cartridges BB's can also be serviced with the yellow spanner. The cup is run up to the bearings and then the lockring is secured. Note there is no bearing adjustment in this system

The tool engages two notches of the adjustable left bearing cone (2nd pic). Rare cup and lockring cartridges BB’s can also be serviced with the yellow spanner (3rd pic). The cup is run up to the bearings and then the lockring is secured. Note there is no bearing adjustment in this system. Nowadays the best use I found for it was while wrapping the handlebar of a road bike (4th pic)

At this point you might wonder what happens with the Park Tool reference SPA-3. Does it exist? Well, it does. But I haven´t seen one so far. It took me a lot of time to find a presentable picture of this tool and some information.

Blue and black peg spanners are top-rarity Park tools. SPA-3 has the ends facing one to each other. I don´t know the intended use for both tools. It seems the blue one can be used for adjusting old french bicycles headsets and the black for extracting crank bolts dust cups/retaining rings

Blue and black spanners are top-rarity Park tools. SPA-3 has the ends facing one to each other. I don´t know the intended use for both tools. It seems the blue one can be used for adjusting old french bicycles headsets and the black for extracting crank bolts dust cups/retaining rings

Meanwhile SPA-6 uses replaceable pins of approximately 2.2mm in diameter. The distance between the pins is adjustable, allowing use on virtually all hanger cups using pin holes. I have to say I do prefer fixed pegs as they are faster and more comfortable to use.

I have never faced a situation where you need to use the pin spanner wrench with such a distance between pins on a bicycle as in picture 2. Pin holes are likely to be close one to each other and thus more convenient a regular pin/peg spanner

I have never faced a situation where you need to use the pin spanner wrench with such a distance between pins on a bicycle as in picture 2. Pin holes are likely to be close one to each other and thus more convenient a regular pin/peg spanner

Brompton rear frame clip for older models

One of the most frustating things in pre-2007 models is the lack of a mechanism that stops the rear triangle from folding when you lift the bike up.


Got it from Brilliantbikes.co.uk that delivered overseas some Brompton parts faster than any spanish dealer

In order to update my 1999 Brompton the retro fit kit is needed as it comes with an 8 mm seat clamp bolt. If you are using already a 6mm bolt there is a much cheaper kit for sale without the clamp lever, £9 instead of £23,75

Packaging content

Complete retrofit kit

The installation process consists on two steps.

First you will have to modify the rubber damper discarding the conical buffer disc (aka suspension block bolt) for the one that have a recess to engage the latch lever.


Suspension block bolt disc to be replaced


Appearance of the new disc bolt. This time is inserted thru the elastomer from the other side

A plastic shim washer (SW), a stepped nylon washer (C) and a nut (N+BW) is necessary to hold the block (SB) from behind when fitting the new buffer disc bolt (BD) as shown in the picture (Fig. QR10). Grease the bolt not to have funny noises. After installing the bolt make sure the small hole is in the bottom position and thus the two tiny lines marked in the disc facing up.

Follow the steps shown int he picture

Follow the steps shown in the Fig. QR10

Secondly replace and discard the old quick release bolt. Three parts will be assembled inside the seat clamp band (SCB) of the bike in the order and orientation shown in Fig. QR05: a hollow stepped cylinder (S), the metal lever (L) and the spring (T). Assemble the parts sliding them with the quick release in angle.

New seat clamp and parts inside the frame band

New seat clamp and parts inside the frame band

Tighten the seat clamp by using a nut and the required metal tabbed washer (SCW) for M8 bolts. Fig. QR06


For post-2007 bikes use the existing flat washer instead (M6W).

At this time, the installation is fully functional but not complete. The kit does comes however with an ergonomic black handle (HDL) that protrudes much longer than just the metal lever. Secure it to the lever with the self-tapping screw (STS). Fig. QR 07


My bike now updated :mrgreen:

And this is it.

For further instructions you will find helpful the video from the official Brompton Channel on Youtube. Hard to find better technical advise and spoken english. Well done.

Rohloff axle plate types & Speedbone vs. Monkeybone in the OEM2 configuration

The axle plate is the Rohloff solution to tackle the inherent phenomenon of axle rotation and twisting in all internal gear hubs (IGH).

Historically this rear wheel issue has been easily solved in threaded axle hubs by using non-turn washers at the axle nuts or alternatively installing an ugly long brass arm clamped to the chainstay.

But since in 1998 Rohloff became the first high-end IGH offering a quick release version (and the unique until NuVinci added a QR option last year) a new design needed to be implemented instead of manufacturing a solid thru-axle with two flat sections where secure the tab washers.

Shimano anti-rotation washers to fit different dropout angles

The quick release (QR) is one of those features that are a MUST on a bike as it offers ease of wheel disassembly. Aside the low entry specs market, on mountain bikes the percentage is close to 99% except those riding single speed hubs or heavy load duties (tandems and so on).

The Rohloff was intended since the beginning for the top notch MTB/flatbar hybrid ghetto. Heavy duty all terrain bikes to sum up. That’s the reason it only came out and remains with a 135mm axle width and only flatbar shifter installation possible.

The axle plate in the Rohloff speech is the invention that will engage the hub securely preventing the axle from twisting whilst the rider applies force on the pedals, and also turning when shifting providing crispy gears. In physics this force is refered to as torque and must be secured somehow to a stationary point.

The axle plate comes in all RH units, and is part of a modular system that makes any frame with 135mm spacing, and any brake system out there, compatible with its assembly. There are three plates available.

Axle plates

Picture taken from the Rohloff Owner’s Manual

They all have a hollow peg where the skewer passes through (remember this it’s not enough by itself to secure the hub) and an appendix or slot in its outer diameter to seat it properly to the frame. The difference between the three options is the fastening point to the frame.

Most of the times in a certain bike setup more than one solution is elegible. It will depend on the user/framebuilder preferences. As a consequence, there are many combinations possible because the axle plate choice should be pondered over with the core issue of how are we going to remove the chain slack in bespoke configurations growing the alternatives.

Let’s see some in the flesh:

  1. Bikes with rim brakes installed will have to use the standard axle plate with a long torque arm attached to the chainstays.

No disc brake and no RH dropout design means long torque arm

If the frame has an unused IS disc brake mount, the long torque arm can be removed and OEM2 mounting is doable by using the lower support hole.


Standard 135mm ATB frame with disc and rim brake compatibility


OEM2 axle plate view using the torque support bolt method to remove the long arm

Some users riding touring bikes with no disc brake mount or frames with special needs, managed to remove the long arm screwing torque support bolts on the mudguard/carrier fittings or close locations.

An odd place to attach the axle plate on an elevated chainstay model


Classic homemade upgrade to avoid the hassle of the chunky torque arm

From now on OEM and OEM2 plates will cover the specific issue when installing the bike on a disc setup.

  1. For standard MTB/ATB disc brake frames exists the OEM2 mounting. This is the one to consider when upgrading a bike or for simplicity reasons. I’ve got it in my bike as it came originally with standard vertical dropouts and a conventional drivetrain.


OEM2 axle plate with Speedbone

Now it is time to introduce the Speedbone. In the previous picture you can see the plate engages the shiny pin of a bigger arm called Speedbone that goes screwed to the disc brake adaptor from the other side of the frame mount.


The Speedbone is placed in the ISO brake mount and weights 72 grams

The Speedbone has been superseded since the Monkeybone allows to anchor the axle plate directly to the disc brake mount adaptor with no downsides. Very clever!

monkey_bone_setup_left 3

The body of a conventional brake adaptor has been machined to adopt the OEM2 axle plate

In any case the Speedbone is still necessary if you’ve got an IS direct mount brake caliper.


My previous setup with a Magura Marta SL IS caliper

The Monkeybone is a witty solution but not suitable for frames ready to go with postmount brake calipers though. Its groundbreaking appearance (sourced by an independient company) forced Rohloff to include it within the official accessories considering its importance. We will see shortly why.

  1. In an attempt to simplify the RH configuration the company specified since the beginning what they call frames with RH ready OEM dropouts. This dropout uses the OEM axle plate and is easy to implement when you create a bike from scratch avoiding the hassle of the Speedbone and also the long arm present on bikes with standard brakes in order to secure the torque. Framebuilders could take advantage of an axle plate that comes this time with a notch resting in the lower position unlike the standard and OEM2 plates.


OEM axle plate only for Rohloff dropouts. 3/32″ chain and no chain tensioner observed means the frame has an eccentric bottom bracket

This axle plate is the favourite choice in custom bike builds where no conversion is needed (with or without removable dropouts). Since you can decide the features of the frame you want to ride and hence the dropout style, you can combine a RH OEM dropout with a sliding system to take up the slack in the chain saving even more weight.


OEM implementation with sliding removable dropouts on top

On disc brakes where an IS/PM adaptor is necessary (the most common configuration, 95% of users?) the alternative of the Monkeybone has gained atenttion. With any type of rotor size compatibility in option and considering it integrates the look and functionality of the Rohloff OEM dropout design (even lighter) there is no need for framebuilders and users to stick to a pure RH frame just in case they want to move back to standard transmissions and also reducing frame costs. This is something to bear in mind as I said before with the method desired to provide chain tension.

All in all, 90% of bikes over 1000$-€-£ and suitable for a Rohloff have disc brakes. That’s the importance of the Monkeybone. Nearly every single mountain/hybrid bike frame will be likely and preferable to be used with the OEM2 axle plate relegating the OEM axle plate, and thus the specific design dropout, to a 10%-15% of community wishing custom builds with rim brakes and/or sliding dropouts combinations.


Ridiculously deprecated Gustav M Speedbone that only saves some grams as improvement

Finally, I’d like to point out that all the axle plates come with 12 holes drilled equally around the circumference. This hole pattern allow adjustment of the external gear mechanism in steps of 30º so that all type of frames can receive an optimum cable routing from the rear wheel.

Shimano Center-Lock vs. 6 bolts disc hubs & rotors

How quick time goes! It’s ten years already since Shimano released its own mounting system for disc rotors (XTR 960 groupset) … and still not popular in our bikes! Why?

Centerlock is a Shimano propietary method of attaching brake rotors to a wheel hub. The disc rotor offset is the same as international standard so that a Shimano Center-Lock rotor and hub are compatible with any brake caliper system around.

First Shimano Center-Lock disc rotor: XTR 960 SM-RT96

First Shimano Center-Lock disc rotor: XTR 960 SM-RT96

Legend has it that Shimano came out with Center-Lock after facing losts of warranty issues on their hubs in just a couple of years. Just imagine the consequences of stripping the threads or round a head bolt. Nothing a bike mechanic has not ever dealed with. I think it was an idea that simply came up considering manufacturing costs process.

Cyclists usually complain about how often companies renew their catalogues and technologies. But in this ocassion I’d like to stand up for Shimano Center-Lock interfaces considering all the advantages they brought up and how fast Shimano reacted to develope a new standard.

It seems we are undergoing a revival breaking the deadlock. That’s why I would like to sum up all the pros and cons of having them installed. With only two downsides the choice it is only a matter of money 🙂

  • Ease of assembly and removal saving a lot of time and making life easier to those riders that often travel and disassembly their rotors not to suffer any damage in transport.
  • Slightly lighter hub. Even though the lightest rotors in the market are not Center-Locks.
  • You can still use an adapter to convert to a 6 disc bolt pattern.
  • As for as performance and reliability none of the two designs are better, but Center-Lock still prevents stubborn bolts or ruined threads.
  • The diameter of the hub flange is smaller in Center-Locks. As a wheelbuilder you will find a lot easier with certain hubs to have less spoke length discrepancy between left and right side, specially in front disc hubs where one of the sides has no dish, and as a result, a more similar tension in both spoke sides. Remember that spokes are likely to come loose with low tension, and not dished side of them will be tensioned accordingly less. If a 6 bolts hub has been built with both oversize flanges just to minimise this effect, it will be for sure much heavier. For example XT 756 vs. XT 760 front disc hubs. I’ve come across with 8-10 mm shorter spokes in 6 bolt wheels, even though front wheels carry less stress and are much more reliable by themselves so that spoke tension is not an issue. About the rear ones there is no difference at all.
  • You need a cassete removal tool instead of a more common T25.
  • Larger range and availability of 6 bolts rotors.

Presión ideal cubiertas bicicleta de carretera

No siempre la presión máxima indicada por el fabricante en la pared del neumático es la ideal para sacar el máximo de nuestras pedaladas.

En superficies lisas, como la de un velódromo, cuanta mayor presión mejor, pero en terrenos irregulares como una carretera llegado a un valor de compromiso se obtienen pérdidas extra por rodadura. Esa presión ideal depende del peso del conjunto ciclista/bicicleta y del tipo de neumático que usamos, su anchura y carcasa entre otros.

Esta genial entrada de otro blog lo explica con algo más de detalle.

Adjunto tablas del fabricante Vittoria con presiones recomendadas para cubiertas de pequeño balón, es decir, las que se usan normalmente en bicis de carretera o ciudad.


Presión-peso-tpi carcasa

Orbea Lanza 29er 2010 (1/2)

En 2010  Orbea España ofrece por primera vez un cuadro de aluminio para 29″. Hasta ahora existía el Alma de carbono en talla 18″ únicamente.

Se estrenó con un montaje medio. 200€ más caro que su hermana  de 26″.

Rear derailleur: SHIMANO XT
Front derailleur: SHIMANO DEORE
Wheels: MAVIC 29″ TN719 DISC
Sprockets: SRAM 11-34 9S
Pedals: SHIMANO PD-M520
Seatpost: ORBEA OC II

Peso real: 13,05 kg (L/20″)
Peso catálogo: 12.45 kg (M/18″)

Precio cuadro: 483€
Precio bici completa:  1199€