Showing posts with label wheels. Show all posts
Showing posts with label wheels. Show all posts

Thursday 1 April 2021

Chuck's Tech Opinion: How to decide what to keep and what to change on a Raleigh Twenty, and Pedals!

As you work on a Twenty, you start to get a feel of the engineering. I find it useful to categorise: some parts are really well thought out and function well, others are merely adequate for their job and there's another category of redundant, useless, or poorly designed stuff. Then layered over that, some parts have elegance, possibly even beauty, while others are downright ugly. Add yet a further layer, namely weight, and a recipe emerges as to how to go about deciding what to keep and what to change. 

Take the pedals. In the photo below (starting top left and going anti-clockwise): originals off a BSA 20, modern MTB style polymer flatties (BBB brand) and a generic polymer trap-type pedal:


Both the modern pedals have reflectors, today a legal requirement for safety, whereas the R20 pedals do not. Now, this R20 pedal has a certain elegance, it's true, but it's also narrow. Uncomfortable over a length of time, especially in soft soled shoes, as your feet curl over it. The weights add another factor:

Pedal type g per pair
R20 651
MTB Flatties 336
Polymer Cage      286

I think it's remarkable that the old R20 pedals weigh so much, nearly 1.5lb! I discarded the polymer cage, for two reasons: the bearings on one were notchy and I didn't like the style for this bike. I thought it would be funky to have the MTB flatties. Apart from the beautiful wide platform they provide, the reflectors for safety and the weight saving (a stonking 315g), they are also shorter (12.1 cm v 11.0 cm from crank to pedal tip) and thinner, both of which reduce the chance of a pedal touching the road in a corner. So, my choice is made to switch to the MTB Flatties. 

That all sounds great, but then I tried fitting the MTB Flatties and to my surprise while the diameters were comparable (9/16"), the threading was different! I wondered whether the cranks had some old English threading, but that seems like an odd explanation, because I've managed to get modern pedals on a R20 before and know that others have too. More likely, perhaps the threading tooling that Raleigh used was slightly different to modern standard. It could be just some R20s that were like this. I tried a few pedals and I found that most of them were too tight, but one or two modern pedals went in ok, but only on one crank. Whatever the reason, after playing about a bit with modern pedals, I now feel that for this project, I will stick with the original pedals. They are a basic, but serviceable design. The end cap prises off carefully with a thin screwdriver. Underneath, two spring clips and a washer to remove:


There are no BBs just a plain bearing. The axle at the top simply slides into what looks like a tapered sleeve in the pedal, then the washer with flats is added and the two spring clips to hold it all down. This one was gummed up and a quick clean and regrease worked wonders. They spin super smoothly now. At least they are hardly worn and have plenty of service to give. They'll clean up ok and add to the retro look. 

Now consider the light bracket:


What an ugly lump that is, and given modern lights, it's redundant too. It serves a purpose in the headset, that is to increase stack height by a few mm in order to prevent the top lock nut from bottoming out. But that function can be easily achieved with a small standard spacer. How much does this monstrosity weigh? 77g! That's about the weight of SEVEN AAA batteries! Wowsers. Guess where that's going? Yes, in the recycling bin. NB, you have to remove the front brake caliper to get the stem out in order to lift this off the headset (see my post a few days ago on that wire loop thingy that restricts the movement of the stem vertically).

Note that by just by changing pedals and ditching the light bracket, you could save nearly 400g. Astonishing. 

You can repeat this thought process for every other item on the R20, using the factors I suggested at the top of this post (I'm not considering maintenance items, such as brake pads, tyres, BBs, chain and cables):

Sturmey Archer hubs (both the front one and the rear epicyclic AW gear unit): 
Elegant, well thought out, very functional, design kudos, unique, a bit heavy, but worth it! Pretty when clean and polished! I would keep these in nearly every case, unless there was a radically different vision for a particular build. 

Chainset: 
They are not all the same. Some patterns are indeed beautiful, others look more functional, but they have some eye appeal, I like the stamped "Nottingham Knight". They function well if you can deal with cotter pins and can live with the heavy chromed steel.

Bottom bracket:
It's perfectly functional, and isn't heavy, so in my view, this comes down to condition, and how important it is for you to change the chainset/eliminate cotter pins. The axle is a solid thing, and very rarely needs replacement. So, a good service with new BBs is usually all that's needed if you stick with cottered cranks. However, if you want to open up the world of square taper chainsets, then I believe that the simplest and best option is to find a square taper axle that fits and retain the same bottom bracket cups and 1/4" BBs. If that's not possible, then face the shell to 73mm or even 68mm (the width of my BSA 20 shell is 77mm as best as I could measure it), and rethread to standard 24 tpi. Some say that you should fill the threads with with a suitable molten metal before re-threading, but I've also read that many people have had success just rethreading directly, but slightly deeper than the original threads. Clearly a specialist's job. Failing any of those, then a problem solver may be a new threadless (friction fitting) unit. 

Saddle:
Really ugly, uncomfortable for me, and enormously heavy! It's gotta go. 

Seatpost:
Ugly, too short for many people, and very heavy, especially being steel with the steel clamp. Easy swap out to a modern one 28.6 usually. It's gotta go. 

Chrome steel Handlebars and Stem
Function ok, and have a certain elegance. However, they are really rather heavy and often this is were customisation and your personal vision take over. A quill stem, with alloy riser bars, or bullhorns, etc. 

Hand grips:
Yeuk! Hard ugly plastic and short. The only positive thing I can say about them is that they are hard wearing. But, I really think they have to go in just about any project (save for a restoration to original spec). 

Chrome steel rims:
Work ok, but do not brake as well as alloys, especially in the wet. Look nice when clean and polished up. Heavy! My front wheel without nuts, rim tapes, or tyres weighs 940g. With rim tapes, tyres and nuts it weighs 1547g. Go or stay? It's really one of preference and also considering the condition of the steel rims that you have, the hassle of doing a rim swap, or finding/building another wheel that fits and also brakes that work with them. On the other hand, if you're not accelerating and braking a lot then, a heavy wheel provides a nice flywheel effect for steady riding - which is what I tend to do on a Twenty. 

Nylon bushing top part of the headset: 
Functions just about adequately, especially if you get a chance to clean it and lube the surface that touches the steerer, and adjust the headset properly. Once the light bracket is off, there's not much in the weight. So this one is a matter of preference again. This photo is of my current project, rust cleaned off and polished. I've kept the Nylon bushing, but ditched the light bracket (hence the black spacer):


Another approach is to remove the Nylon bushing and install the top half of a 1" threadless headset. When I do that again in the future, I'll be sure to take enough photos and post them on this blog. 

Frame: 
It wouldn't be a Twenty without one! It's a classic, has got to stay.

Forks:
They are designed to fit the cone flanges of the Raleigh Sturmey Archer front hub and they work well enough. A bit heavy. I think this one is mainly down to whether you keep that front hub or not. Also whether you want to do something funky, like BMX forks for 451 or 406 wheels or suspension forks. In which case, you can also change the whole headset. 

Paintwork:
What condition is it in, and do you like it? Will it clean up nicely (after a wash, T-Cut and car polish)? Simple as that. 

Clamps and Locking levers on steerer and seat tube:
These function adequately if well-maintained and positioned properly (evenly over their respective tubing slots). They add a bit of weight, but also provide easy quick adjustment. Also, if you are fitting a quill stem, the front clamp becomes unnecessary and can go (or stay!). So it's really up to you. 

Brake caliper units:
Can function adequately if you take the time to set them up well, and they polish up ok too. Remove rust with WD40 and 0000 steel wool, chrome polish, lubricate and fix and adjust them properly. Use fresh cables. In many instances, I've changed only the inner wires, as the outer cables were fine. If the ends of the outer cables are kinked, you can snip off 5-10mm cleanly and that will improve the performance quite a bit. Modern alloy units would be an improvement and weigh less, but I think this one is really a matter of preference.  Here's a front caliper, with rust cleaned off one arm, but not yet the other one:



Brake levers:
In my view they function adequately, and being steel are better than plastic levers! But there are lighter and better modern alternatives. So, it's a matter of preference for your particular build I think. 

Mudguards (Fenders):
Functional, but do not have the break-off arms for safety as modern ones do and are relatively heavy. Must mount them properly and securely, or those beefy mounting arms could foul a wheel and cause a bad accident. I'm powder coating mine on this build.  

Chainguard:
Serves a function (keeping your trouser leg clean!) and has a certain appearance. Don't weigh a great deal, but grams are grams. It's up to you! I'm powder coating mine on this build.  

As I've said before, the Raleigh Twenty is like a blank canvas to a bike builder! The Raleigh bronze green BSA 20 that I'm working on at the moment is going to retain most of its original components, but with modern contact points (pedals, saddle/seatpost and hand grips). The next one may be a light weight with funky bars and alloy rims, but I haven't clearly figured out my direction on that one at this time.  

Go with your heart and desire, enjoy the process, and all will be ok. Be creative, be artistic! 

Monday 29 March 2021

Raleigh Twenty: Front hub service, removing rust chrome wheels

The 46T 165mm crankset off the BSA 20 is utilitarian, but good looking, after the rust is removed and the chrome polished. I especially like the little "Nottingham Knight" stampings. Virtually unworn teeth:


OK, it's cottered, but I'll make sure to assemble it with anti-seize. I tried removing some rust with Aluminium foil and water, and while it works, it can cause scratches, probably because solid particles can get dragged about under the metal foil. I prefer using 0000 wire wool with WD40. That removes rust quickly and minimises scratching. Here are some before and after shots:

And another one:


In this one, the bottom part of the front hub has been cleaned, but not yet the top part. You can see the yucky grease solidified into varnish. Easily cleaned with WD40 and a small piece of green plastic scourer. This is probably the first time the hub has been opened since 1978! 


Note also the 3 cross spoke pattern, but interestingly, the crossing spoke goes over the first, second AND third spokes, not under the third, as is often the case on larger wheels with 3 cross lacing. And here's the other side, all clean, ready for balls (10 BB each side of 3/16"):

Like the chainset, there's a lot of character in these late 70s Raleigh Sturmey Archer front hubs. They are actually very well thought out in my opinion, as I'll describe further below. 


Here are the parts. Note that both cones have a small flange turned on them, but only one cone, the moveable one, has flats to make it a nut. That's because it is used to adjust bearing play - while the hub is on the bike! The other cone on the axle is intended to stay fixed - there's a stop on the axle to prevent it passing further along the thread. Note that neither cones have locking nuts (90mm across the outsides of the cones). 


You have to hand spring the front fork slightly opening the front dropouts a tad to let the flanges of each cone fit in. I measured my forks at 87mm across the insides, so that's a decent 3mm spring. Once in though, the hub will stay put, held by the cones, even before you put the nuts and washers on the outside of the forks. So, the clever bit is that you can adjust bearing play by sliding a cone spanner inside the fork on to the flats of the cone nut, and turning slightly. Once set, tighten the outside washers and axle nuts, and that holds it all down. Quite neat and clever and they run pretty smoothly (even this one despite the wear groove in the cone). Just remember to put the fixed cone on the right (drive side) of the bike, because on the other side, there will be a natural tendency for the bearing to tighten, which can be harmful to it. As an experiment, assemble and hold the axle ends in your hands, give the wheel a spin and fiddle about - it's easy to see the natural tendency of the bearing to tighten up when the fixed cone is on the left, and the natural tendency to loosen with the fixed cone on the right. But don't worry, they won't loosen in use, because the external nuts lock everything in position. 

For the inner tube side surface of the rims, I simply spray a bit of WD40, brass wire brush and then a quick going over with a slightly coarser steel wool. Wipe it off with a small cotton bath towel, and hey presto, clean insides ready for rim tape. For the Sturmey Archer AW I merely oiled it using a cheap plastic pipette and 1:3 mix of car transmission fluid to 5W engine oil. The pipette allows a small measure to be squirted easily into the oil port. That three speed tickety tick! As they say, AW stands for Always Works...


So here they are, shiny chrome wheels, and hubs, bling bling! After a bit more tightening and truing, I'll dress them in new white-wall shoes. 

Saturday 16 August 2014

The best way to seal Cyclocross Tyres? SeamSure v SeamGrip v Copydex

I may have finally found the best way to seal quality CX tyres like Challenge open tubular (clinchers). In a previous post, I compared Copydex glue with SeamGrip. Both work, but Copydex peels after a while and the SeamGrip is really gloopy and messy to apply. Water based SeamSure is way easier to apply:
It's a milky solution that is dead easy to brush on to the sidewalls of the tyres. Another easy way is to smear it on with gloved finger. A bonus is that you can wash up with warm water and soap. It actually comes in a bottle with an integrated brush, but I didn't bother with that, and instead used a better quality half inch wide paintbrush.

According to the package literature:
"Seam Sure is a fast drying water based urethane formula designed for sealing sewn seams on synthetic fabrics and breathable laminates. Seam Sure dries to a clear, flexible, long lasting film with a nearly invisible, non-gloss finish. Seam Sure is washable, dry-cleanable and freeze/thaw stable". 
Now doesn't that sound perfect for CX tyres?
Amazingly easy to apply and it does indeed dry almost invisible, with a matt finish. The only question then is how will it survive the cyclocross season? I will find out over the next months and let you know.

Friday 4 July 2014

Giant Defy Mudguards or "Fenders", Review

Giant's hugely popular Defy range of road bikes have mudguard eyelets front and rear. However, clearance under the brake calipers is tight. Giant produce mudguards (finders in English(US)) for the Defy, Avail, Rapid and Dash frames. However, I've heard people, even shop mechanics, say that these don't fit on a Large Defy frame. This post is about my attempt to fit them and I'll give my opinion at the end.  
Those are stainless steel braces that go round the brake caliper area. They are 700c x 35mm. My Large size Defy 4 has 700x25mm tyres. The frame does not have a chainstay bridge, but it does have a hole in the seat tube (behind the bottle mount area) to mount a mudguard. However, the slot in the forward portion of the rear mudguard (at right in the photo above) does not reach this hole. So, the first thing is to test fit it in position, mark the position for a new hole and drill it like this:
Then I put some electrical tape over the slot (no need to allow the muck through!):
That's the only modification required. The whole gubbins then attaches as normal, which is totally straightforward. I decided to use a rubber washer on the inside (made of inner tube) to prevent cracking the plastic as I tightened the bolt and to help with vibration:
From the other side, here is the rubber bung (grommet) that the bolt goes through before tightening into the seat tube hole:
Very sensible design. Here is the rear mudguard all fitted. It's very easy to line up and keep off the tyre:

The front guard posed no issues at all. Here's the bike with the mudguards fitted. I think the "fenders" look quite neat:
All in all, they look and feel like good quality items and there seems to be nothing on them that rusts. They are very low profile and coverage is better than SKS Raceblades. The Giant mudguards seem more sturdy than Crud Road Racer Mark 2's, maintain clearance from the tyres very nicely, and they don't have any brushy things, as on the Crud's, to contact the rims. However, they have traditional wire mounting rods, unlike the Cruds or SKS which have break off parts for safety. They provide a great solution to turn your road bike into a commuter or winter bike. It is possible that they would fit other road bikes too, but you'd need some kind of mod to attach the rear one to the seat tube. Time will tell how long they last, but so far so good. Oh, and in my view, it's not right to say that they don't fit on a Large Defy frame. Sure, one needs to drill a hole in them, but that's easy. Overall, I rate them very highly: 4 Stars out of 5 (would be higher if the arms were the break off type).

Sunday 2 February 2014

Argon 18 E-80 Build Log: Part 2

The finished bike. Fine adjustments (e.g. saddle and tt bar angles) are still to be finalised. I'll do those as I test ride. Those wheels are sheer bling! Supra I think is a rebadged version of FFWD. These are 58mm carbon alloy clinchers, so not the lightest, but reasonably aero.
The cockpit, Profile T2 Wing base bar, Token extensions and Zipp clips n pads. Brake levers are ultra cheap Dia Compe. Why this combo? Well it's what I had - the only part I had to buy is the Zipp clips. The ride is comfortable and smooth. Fairly lively frameset it seems. I'll learn more as I test ride.
I didn't bother changing the left hand gear lever, as it was for a double anyway. So I have a nice black grey thing going on, to match the front and back fork colours. Totally by chance. 
 Basic Tektro brake calipers. They work fine. External cabling, easier maintenance, but less aero. This is a 2009 frame.

 Above you can see the frame clearance for 23mm Michelin Pro 4 Comp tyres. I reckon 24 or 25mm tyres could be accommodated if desired.
 Just love that rear carbon wishbone. Flowing lines. Yes, those are SPD pedals. That's what I use.

Topeak aero rear light, is an easy fit on the Thomson seat post. May as well use that space above the seat tube fairing. 
My old Pro-Lite Bracciano wheels are much lighter than the Supras and may come out on windy days or for hilly TT courses. 

Next some fettling, position honing and test riding. Then on to training... 

Sunday 19 January 2014

Challenge Tyres: sealing side walls Seamgrip v. Copydex

These Challenge Grifo are beautiful clinchers. Note that Challenge call them Open Tubulars meaning they're made like their tubulars before fitting a clincher style bead. Extremely high TPI, so very supple. Since they're made of cotton, it is advisable to seal the tyre walls. I've done an experiment here, top one is sealed in Pritt Copydex (latex base solvent free glue). It had nil effect to the feel of the tyre. 
The one below is sealed with McNett Seamgrip, a tent and camping equipment sealant. Of the two, I found that Copydex is much less messy to apply, but no where near as robust as the Seamgrip. In the photo above, you can see the edges peeling. However, after a number of cross races, the Copydex had not come off. So, it's worth doing, even though the Seamgrip is better. The Seamgripped carcass was perhaps a tad less flexible, but the main drawback was it's gloopy consistency and difficulty in application. Ideally, if the Seamgrip could be diluted down a bit before application it may be easier, but I fear that can only be done with pretty nasty benzene based solvents. If anyone knows of a harmless solvent for Seamgrip, please do comment below!

Monday 21 January 2013

Snow!

Time to have some fun on the cyclocross bike. There's nothing like it! The tyres are Challenge Grifo  700x33 clinchers (what they call "open tubulars", but they are not tubulars!). 

Wednesday 19 September 2012

Tyre Fitting: Tread Direction for off road MTB and cyclocross

Which way round should tyres be mounted for off road use and cyclocross racing? I'm fully aware that some manufacturers have rotation arrows on sidewalls and information on websites and in brochures. However, manufacturer's instructions are inconsistent on the subject, as I'll demonstrate below. And then I'll give my views on the answer!

WHAT DO MANUFACTURERS SAY ABOUT ROTATION DIRECTION?

Off road tyres often have a directional tread. Here is a photo of Michelin Mud2.

The knobs form roughly a V shaped chevron or arrow pointing upwards in the photo above. They are marked on their sidewalls with rotation arrows reading "front" and "rear." Michelin's website says:

"Why a particular direction for fitting?
The direction in which a tyre is fitted will enable the user to optimize the performance of the tyres in terms of braking and traction.
In general, the front tyre is more involved in braking while the rear tyre gives maximum traction.
The rolling direction is marked directly on the tyre by an arrow.
The tyres are also marked “Front” and “Rear”."

Is Chuck satisfied with that? No way! In contrast, this is what the Clement tyres website says:

"Q: Which direction should I install the PDX cyclocross tires?
A: We prefer to install the PDX (and most tires) so the arrow-shaped knobs in the center of the tire face forward when viewed from the top. This is true for both front and rear tires. Some riders may install them differently to get different traction characteristics and that’s perfectly OK!"

The arrows on the side of the Vittoria XG Pro (below) are marked "speed" and "traction".


 The Vittoria website says: 

"Is there a mounting direction for my tire?
Mounting direction is shown by a little arrow engraved onto tire sidewall. In the case it is not visible for any reason, do follow the tread pattern design: if it design an arrow, that has to run forward, otherwiese if the tread pattern itself is specular the tire can be mounted either way."

The Vittoria XG Pro have a similar tread pattern to the Challenge Grifos below:

This is what the Challenge website has to say about it:

"The GRIFO is a very special tread pattern which can be used in both directions!
If you point the arrow < < < of the tread forward the tire is faster having low rolling resistance. 
If you turn the tire around with the arrow pointing backwards > > > the tire has much more grip. In this case it is not as fast because there is an increase in rolling resistance. 
It really depends on the type of course you have. So you can actually find your perfect setup according to the course and your style if riding.
The front tire in most cases is kept with the arrow forward, but in a few occasions can also perform better the other way.. 
The rear tire is usually more suitable to switch directions.
 
Have fun trying !"

MANUFACTURERS ARE INCONSISTENT!

So, summing up the above, Challenge and Michelin seem to be saying that this is usually better (viewed from above):

<<<<<< front <<<<<<< ==========BB========>>>>>>>>  rear  >>>>>>>

Whereas Clement and Vittoria seem to be saying that this is usually better (again, viewed from above):

<<<<<< front <<<<<<< ==========BB========<<<<<<<  rear  <<<<<<<

Faced with this, the thorny issue here is about the orientation of the rear tyre tread. I say there's no issue with the front tyre, because every elite MTB or cyclocross bike I've seen has had the front tyre oriented so that looking from above, the chevron/arrow in the tread points forwards and this has always been consistent with the manufacturers recommendations that I've seen.

WHICH WAY IS BETTER?

As to the rear tyre, I've looked at hundreds of photos of elite riders' MTB and Cyclocross bikes on t'net. This includes a number of ex world champions and national champions (eg Stybar, Wyman, Field, Nys). I found the following:

Out of nearly two dozen bikes of elite riders, only one had the rear tyre oriented so that the chevron/arrow points backwards when viewed from the above. The one exception was Tim Johnson's MTB bike (he's more known for CX) on which he had the rear tyre (a Schwalbe Rocket Ron) the other way, with arrow pointing back when viewed from above. The vast majority of bikes had the Vs pointing forwards on both tyres when viewed from above. This included some fitted with Michelin Mud2s, which as I explained  have arrows on them indicating that the rear and front should point in opposite directions. In other words, the riders do not follow the manufacturer's arrows!

I would rate the empirical evidence and practices of world and national CX and MTB champions very highly - presumably they've done enough qualitative testing and timing to form a considered view. 

I run Michelin Mud2 on my CX bike and I've tried them in both configurations. To me the one with the V on each tyre pointing forwards (as viewed from above) works best. Why should this be? Well it could be a placebo effect - that I'm gaining some positive vibes by simply doing what the pros do! 

On the other hand, perhaps there is another reason. Going downhill across a slope, making an off-camber turn, is one of the more risky manoeuvres in cyclocross. The bike can wash out sideways very quickly on a greasy surface. Let's examine that situation a bit more. One is rarely driving the rear wheel hard and may even be braking a bit, front and rear. The diagram below shows the angle of the chevrons as they contact the ground. The green arrows indicate the direction of the slope. In each example A and B, the tyre is rolling from right to left. In other words, not straight downhill, but slightly across the slope. The red oval shows the contact patch schematically. I've put it on the uphill side, because that is the part of the tyre that contacts the ground in this situation. You could imagine the grey chevrons as tyre prints in the mud. Think of the arms of each chevron on the tyre as little skis! In example A, the tyre is mounted with the Vs pointing backwards as the bike is viewed from above. You can see that the uphill arm of the chevron - in the contact patch - is almost parallel with the slope. It is likely to slip easily just like a ski pointing downhill. In example B, the tyre is mounted in the conventional way for a front wheel - that is, Vs pointing forward when looking at the bike from above. In the contact patch, the arms of the uphill edge of the chevron are roughly perpendicular to the slope. The skis are cross-slope in like a skier digging in edges on a side slope. If you're not convinced about the ski analogy, remember that the rider may be braking. There seems to be a clear advantage of B over A, at least going downhill.

Uphill, you can use the same diagram as above but imagine the tyre rolling from left to right. A has tyres mounted with the Vs pointing forward as seen from above. However, uphill, you will be travelling slower and probably not braking. B seems better than A. I guess that's what makes a good tyre tread design - functioning well in both directions. Remember, the diagram above is very simplified - for one thing, it does not show the edge tread, or the diamonds filling out the chevron in the middle as in the Grifo and Vittoria XG Pro, both of which are bound to affect performance. 
.
CONCLUSION

So, having tyres fitted like Vittoria and Clement seem to prefer (Vs pointing forwards front and rear when viewed from above) appears more sure-footed for off-camber downhill tracks and cross-slope descents. It seems to be the more popular approach for pro riders. It's also supposed to be the faster orientation according to the tyre manufacturers. However, reversing the rear tyre could be worth a try e.g. where there are significant stretches of slippery off-camber uphill on the course.

Monday 14 May 2012

Quick Release lever alignment

Michael Barry, the Team Sky professional rider, recently wrote about his favourite cycling innovation, the humble quick release lever (article here). The other day, I looked idly at bikes in a public rack. I noticed that people position the closed lever in many different orientations. Which way should QR levers point? A good subject for a "Chuck's Tech Opinion," I mused.
Sounds like a trivial matter? No way, I say! A good friend of mine had a minor crash on his beautiful all carbon bike. The front fork was gouged by the QR lever - a very expensive mishap. The lever had been locked in front of the fork blade, pointing up. I've also heard stories about a person who pulled a bike out of the rack, and only when riding discovered that the QR lever had been snagged open!

When you examine pro bikes, it's very interesting, as it seems that rear lever alignment is team, or should I say team mechanic, dependent. So, for example, TT bikes from Radioshack/Leopard Trek (including Cancellara), Vacansoleil (including Larsson), Saxo Bank (including Boaro), Astana (including Brajikovic) have the QR lever on the rear wheel pointing backwards, as in the photo above. The others have the QR lever positioned under the chainstay pointing forwards (e.g. Team Sky), or back and up, or in the crook between chainstay and seatstay like this:
"In the crook" also appears to be the way most pro cyclocross riders orient the rear wheel QR lever. I guess that is because the risk of snagging the lever (e.g. by a passing bush!) is lower in this position (it's tucked into the stays, which protect it a little). Another thing the pros have to worry about (but I don't!) is ease of access for wheel changes.

When it comes to the front QR lever, it's much simpler. Among the pros, as far as I can tell, it is always pointing backwards. Either under the fork, or backwards and upwards. The other pro thing is that the lever on the front wheel tends to be on the left side of the bike (on the rear wheel it HAS to be on the left side).

So, fwiw, here's my opinion. On the rear wheel of CX bikes and commuters that are often parked in racks with other bikes - where there is a risk of snagging the lever - I will orient it tucked into the crook of the seatstay and chainstay. Whereas for TT, I may have it pointing backwards. It really depends on the frame structure around the dropouts and the shape and configuration of the QR lever. I am not that keen on pointing it forwards and down under the chainstay - but I would do that if there is no other way (it depends on the configuration of the lever and type of frame - sometimes it won't go into the crook without fouling the frame, for example). On the front wheel, it's always pointing back, either under the fork or backwards and upwards behind the fork blade. Usually this is achieved with the skewers oriented so that each QR lever is on the left side of the bike.

And yes, I agree with Mr Barry that the quick release is a great bicycle innovation.

Wednesday 21 March 2012

Toe overlap

Is it a disaster if you have toe overlap?
Obviously, wearing winkle-pickers on a small bike with mudguards does not help! But usually, a bit of overlap is not a disaster, because for general riding, steering inputs are small. However, toe overlap can be very irritating, especially at slow speeds where handlebars are turned more. For me, the worst situation is climbing a twisty road. I'm out of the saddle, putting the watts down, going round a hairpin bend, when whack! At worst, I could fall off.

Over the years, I've developed a sense of the front centres measurement that allows my toes to clear the front wheel. Front centres (FC) is the distance from the centre of the bottom bracket to the centre of the front wheel axles - measured very simply with a tape measure. For me when FC~595mm, then I know that in normal cycling shoes and tyres up to 28mm, toe overlap may be marginal. That is, it may be present, or it may not! I also know that when FC~600mm, clearance is more likely.

If you have a bit of toe overlap and want to get rid of it, you could try changing a few things, for example:
  • move your cleats forward a bit, but of course, this may affect comfort
  • use narrower tyres
  • change cranks to shorter ones - not an ideal solution for a few mm gain
  • more radical would be the change the front fork to one with more forward rake
So, toe overlap is not a disaster, but it can be irritating and possibly dangerous. Personally, I don't like it. I try to ensure that there is no toe overlap on any of my bikes, but that said I will keep a bike that I enjoy even if it has a slight toe overlap. 



Tuesday 6 March 2012

Butyl or Latex inner tubes?

I thought it would be fun to write short opinions on technical subjects. Here is the first one.

Latex tubes roll better than butyl ones. The improved rolling resistance is measurable, quantitatively, for example here. The improvement is real, but relatively small - you could achieve comparable rolling resistance reduction by pumping up the tyre more, or through changing tyres. The competitive edge of latex will be of use to the really top flight racing types. The rest of us have much more to gain through training and improving aerodynamics. There is no weight penalty between the two types of tube, because lightweight butyl tubes are available that compare well with latex ones in grams. In qualitative terms, I find latex tubes more comfortable. They have a wonderful "squishy, yet fast" feel to them. In contrast, butyl tubes give a "harder, harsher" ride. Another factor is that latex tubes need to be pumped up more regularly - pretty much every day - as they do not retain air as well as butyl tubes. I've also noted an odd wear issue with latex tubes. See the photo below which shows some kind of plastic deformation on the inside of the tube - I never figured out the cause.
I had to chuck this one after just a few months use, despite the fact that I had run butyl tubes in the same wheels and tyres for much longer with no issues.

So, if you want fast, comfy tubes with improved rolling resistance and can put up with the extra maintenance hassle, then go for latex. But if you can't be bothered with the extra maintenance (both in terms of time and expense), then stick to butyl.

Wednesday 29 February 2012

Cyclocross wheels from Hewitt

A year on, the folding bike wheels that Hewitt built up for me are still going strong. They are in daily use, straight as they were the day they arrived, with no loose or broken spokes. Filled with that confidence, I decided to get my primary CX racing wheels made by them too. First, I de-spoked my Shimano 105 hubs from their old, worn, Mavic MA3 rims, and serviced them. Front hub:
 Then the rear one. I tend to open the nuts on one side only, and then draw the axle out.
The balls were ok, just needed stripping, cleaning, re-greasing and re-assembly. I tried to work some thick oil into the freewheel too.
A few weeks later, beautifully built by Hewitt on Mavic CXP33 rims:
 The spoke lacing and tension is simply excellent.
Hewitt have a reputation for quality wheels for a good reason. I can't wait to ride them and will update this post after I have done so.