Tag Archives: Bicis

Thinking on removing your front derailleur?


Everytime I come across with this question on a bike forum my thoughts automatically go back to the 2003 Tour de France Prologue.

On that day, the scottish David Millar lost the opportunity to win the initial time-trial for less than a second due to his chain that came off the front ring.

News footage from the French TV shows how brave is Millar placing the chain back with his fingers upon arrival. A delicate operation while you’re riding over 30 mph.

This information points at the missing front derailleur as the reason of the problem.

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David Millar, 2003 Tour de France Prologue, Paris

@ http://www.cyclingfans.com

Yesterday’s chain failure wasn’t the first time that David Millar has experienced a chain problem at a critical time in a Grand Tour. During the 2003 Tour de France 6.5km prologue (photo above), Millar’s chain slipped off as he approached the finish line, costing him the stage win. An angry Millar blamed his directeur sportif for the lack of a front derailleur, causing the chain to slip. Millar finished the prologue second to Bradley McGee by just 8 hundredths of a second.
-Pete Geyer

It’s hard to believe that a bike mechanic involved in such a race like the Tour de France, world class riders and equipment (not the case with Decathlon bikes though :roll:), decided to remove the front mech, because Millar was committed to use a single chainring setup, without fitting a chain stopper on its place.

I can only blame ignorance to be mother of imprudence. Front derailleurs allow to switch from chainwheels, and what is as important: stop the chain from jumping off. On bumpy stone paved roads (pavée) and a NOT enough rear mech to lock up the chain tension while it is working crossed along the cogs we can only predict the chain is going to fall off sooner than later. Even on flat surfaces it will slip off.

Whether if you want to convert your MTB to singlespeed or 1x type transmission, bear in mind you will need a device to prevent the chain from coming off. It can be a double bashguard, a chainkeeper/chainguide/chain stopper or a combination of both.

Posh Paul chain keeper

Posh Paul chain keeper

Many people that are simplifying old vintage road bikes should do the same for fixie/single speed purposes.

All these advises (and devices) are taken into account considering we are talking about pure vertical dropout frames with no other methods to take up the slack in the chain, such us: eccentric BB/hubs, sliding dropouts, and so on, representing the vast majority of frames.

There are only a couple of exceptions that freaks will proudly point out. SRAM XX1 single chainring gruppo and high chain tensioners on singlespeed bikes where the chain works straight! (Bromptons for example).

Even though, I’ve experienced chains coming off in my bike that uses a perfect aligned chain on a Rohloff hub and the extremely high tension provided by the DH tensioner. XX1 failures are even more common, and have been reported frequently despite engineers taking the piss with the deep profile teeth design of the XX1 chainring encouraging not to use a chainguide. I would like to recall that Hermida lost the podium in the last Olympics because of the bloody stupid tendency on bikers to remove the front derailleur and the “cojonazos” of his team fitting new-unproven parts they’d just received.

Hermida’s team underrated the importance of the chainguide that is mandatory on top of the XX1 crankset if you do not install a Type 2 SRAM rear mech. The SRAM XX1 provides extra tension thanks to a roller clutch

If you’re switching to single speed or whatever 1x setup is in your mind, fit a chainguard. You’re not likely to lose a gold medal or the yellow jersey but you teeth instead :mrgreen:. Remember how bad the Cofidis bicycle mechanic should have felt that night after the first stage of the Tour de France: “somebody shoot me”.

Bromtpon Eazy Wheels


Replacing the factory wheels was the first repair that came to my mind when I got the Brompty. Although I did it long ago, I have saved it for last within this saga of Brompton repairs because the result is not satisfactory. I would say work in progress 🙂

Factory rollers vs. Eazy Wheels

Factory rollers vs. Eazy Wheels

By installing the Eazy Wheels you have the added advantage of being able to pull the bicycle along on the ground. Stardard wheels are just simply a shame and won´t work.

I love the idea of the versatility of a Brompton

I love the idea of the versatility of a Brompton

Good, I have no more to carry mine everytime I go walking with it when commuting, I thought. But the reality is that your bike needs also a rear carrier, or Brompton mudguard at least, to support parked mode and wheel it along. Otherwise the Eazy wheels by themselves won´t make any difference. I can’t believe I didn’t figure it out until I put them on. Well, at work I never needed to pull/push the bike around :mrgreen: .

Eazy_wheels_4_close_up

Tyred rollers with industrial bearings can also be fitted to the rear rack

A rubber bung, fitted to the bottom of the seat post, can be used as a brake to prevent unwanted rolling.

Full kit

Eazy Wheels full kit with rubber thingy

My Brompton does not have a rear mudguard that will add the extra wheel for stability, or what it could be even better, a rear rack that comes equipped with two wheels improving the handling when it is half-folded.

IMG_4666

Bikes with no mudguards/rack but Eazy Wheels installed, are as stupid as mine looks in the picture

Not everybody need to enable this function. That is the reason it is offered as an option when placing your order. In that case you will have to pay on top 20 quid for the better quality wheels, and another 50 quid for the pricey mudguards or 100 quid for the Version R of the bike (mudguards & rack).

The installation of the wheels is so straightforward… nothing to say about it. What a drag!

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.

IMG_4590

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.

IMG_4598

Suspension block bolt disc to be replaced

IMG_4605

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

IMG_4607

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

IMG_4602

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.

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-anchura

Presión-peso-tpi carcasa

Tabla de desarrollos para ruedas de 700x23c


Adjunto una tabla que siempre conviene tenerla a mano. Nos da el avance en metros por pedalada según los desarrollos que montemos en nuestra bici de carretera con las habituales ruedas de 700x23c.

Sacamos en conclusión cosas tan interesantes como que un plato compact de 50 dientes combinado con un piñón de 11 es más “duro” que un 53×12, que un 36×25 es similar a un 39×27, o que un 34×27/28 es casi tan bueno para escalar paredes como lo era el triple plato de 30 dientes con un piñón de 25.

De ahí el éxito de los pedalieres compact, que se aprovechan de la amplia gama de desarrollos que poseen los piñones de hoy en día, con 10 e incluso 11 coronas, ofertando un rango bastante bueno de desarrollos tanto por “arriba” como por “debajo” sin tener que montar un sistema de triple plato o el insufrible de los pros con 39 dientes de plato pequeño.

Bicis de montaña con ruedas 650B


Esta medida de ruedas se sitúa a medio camino entre las convencionales de 26″ y la nueva moda de 29″, es decir, unas 27,5″ (en realidad un poco menos). Desde hace un par de años hay usuarios que están montando en cuadros específicos para 26″ ruedas un poco más grandes. La ventaja es su mayor inercia y que pasan por los obstáculos más fácilmente. Lógicamente, no todos los cuadros ni horquillas las aceptan.

Tienen décadas de existencia. En muchas bicis de paseo del norte de Europa son muy comunes. Su futuro en el MTB es del todo incierto pues hay pocos fabricantes de aros, cubiertas y horquillas, además de que las 29er se están haciendo con el mercado de las ruedas “grandes”. Algunas marcas han realizado diseños específicos para explotar todas las ventajas de las ruedas de mayor tamaño. La idea principal es bajar la altura del pedalier respecto a los ejes de rueda consiguiendo una bici mucho más difícil de volcar aumentando la sensación de estar metido en la bici y no sobre ella.

Ahora mismo es el tipo de bici que más me llama la atención pues, entre otras cosas, apenas aumenta la longitud de las vainas respecto a las tradicionales de 26″ y no tienen tanto slooping ni los tubos horizontales extralargos tan frecuentes de las 29er.

Independient Fabrication 650B acero

Vicious Cycles Mambo Sun Ti

Vicious Cycles Mambo Sun acero

Kish 650B

Platos de titanio Mattias Hellöre


Hace unos meses le encargué a un sueco, conocido por realizar piezas a medida para bicis, fabricarme  un juego de platos de titanio. Las medidas las puedes escoger tú, 100% personalizables. Así que me decidí por dar vida a un pedalier Shimano LX M563 que me había dado un amigo. Sólo tuve que encargarme luego de pulirlo a base de dremel.

Los platos, a falta de hacerle kilómetros, tienen un acabado muy bueno. Él mismo te realiza el diseño, y aunque le dije que no se preocupase del peso no llegan a los 95 gramos los tres. Son un plato grande de 42 dientes, un mediano de 31 y un pequeño de 21 (raro que es uno :mrgreen:) para BCD 94/58mm.

En la página web del sueco puedes ver sus trabajos. Los presupuestos se los tendrás que pedir a él directamente, pero ya os adelanto que no salen mucho más caros que unos platos XT y mucho más baratos que unos XTR, aunque dudo que cambien igual de bien. Eso sí, ligeros y exclusivos son un rato. Ya os informaré de su durabilidad y desempeño.