Broadway Bicycle School in Cambridge, MA

As a schoolboy I tinkered with bikes, and as a middle aged man I’ve continued my amateurish fiddling. My cheque book is now considerably larger so I can mess around with more bikes and buy bits and pieces for them, but I’ve never had any formal training as a bicycle mechanic and generally just use my experience as an engineer and some common sense to work things out. This works fine most of the time, but I’ve wanted to build my own wheels for a while now and to do that I thought that I should get some real training. So I looked for a suitable course and found that the “Broadway Bicycle School” in Cambridge offered one. There were two drawbacks though, a pre-requisite was their “Advanced Mechanic” course which also had a pre-requiste of the “Basic Mechanic” course. Well a little learning never hurt so I decided to take both courses to gain admittance to the inner sanctum of wheel building.

The Broadway Bicycle School is a full service bike shop in a quaint and cozy store with wheels hanging from the ceiling, a creaky wooden floor, an excellent collection of old chainrings and just enough space for a few bike stands. Get eight bikes and their owners in there along with an instructor and the space becomes even more intimate. But that’s really what this shop/school is all about. It’s friendly and a great place for the bike geek or interested newbie. It’s owned by the employees and they set out to not only fix and sell bikes, but also to teach people how to maintain them. For a small fee they even let you use the shop and it’s tools to work on your own bike. It’s definitely not a store for the lycra clad carbon riding racer, but it’s perfect for the city rider who loves their bike.

I’ve now completed two of five evening classes in the basic course and I can highly recommend them for both a complete novice and for someone who has a little knowledge, but wants to see how to do things properly. Our instructor, Kate, was bright, cheery and knowledgeable and took us through fixing a puncture in the first class with lots of show and tell and then we were set loose on our own bikes. For the second class we got to adjust a cup and cone hub and learned about headsets. I found this useful as it’s been a while since I adjusted an old style hub as I now buy hubs with sealed bearings. Next week it’s brakes………….

The Fixed Sprocket

This is as simple as it gets, just a sprocket screwed onto a hub. If you pedal forwards it rotates anti clockwise, and if you pedal backwards it goes clockwise – there’s no ratchet so you can pedal both forwards and backwards. This “fixed gear” style of riding is how bicycles started out, it’s the mechanism used on track bikes and it’s also become popular with a sub-culture of urban riders who’ve discovered it’s simplicity. To stop the fixed sprocket from unscrewing when you ride backwards it’s retained by a lock ring that screws onto a slightly smaller diameter left handed threading that all fixed hubs have. To install this puppy you need a chain whip……….it’s not what you’re thinking, it’s just a handle with a couple of lengths of chain that wrap around the sprocket so you can get a good grip on it to tighten it. The end of the handle will often be a lock ring spanner too. Remember when looking at the sprocket turn it clockwise to tighten and anti-clockwise to untighten, do the opposite for the lock ring and always use plenty of lube on those threads.

The Freewheel

This sprocket has some smarts. There’s a mechanism inside with a ratchet. If you pedal forwards the ratchet engages and it works like a fixed sprocket and the motion of the chain is transferred to the hub and the bike moves forward. However, if you pedal backwards the freewheel spins freely. The useful upshot of all this is that on down hills you can coast, unless you decided to go down the hill backwards and then the wheel’s motion would be transmitted to the pedals, but no one would do that.

Freewheels are notoriously difficult to remove because the act of pedaling thightens them onto the hub. There are a couple of different sorts of freewheels that need different tools and techniques to remove. Make sure you know what type of freewheel you have and necessary tools. They only cost a few dollars. Shimano type freewheels require spline tool (park FR-1). This spline tool fits down over the axle inside the freewheel and it is retained by reinstalling the skewer. The you grip it with a big wrench and unscrew it by turning the wrench anticlockwise. If it’s tough slip a bit of pipe over the wrench handle to give you some extra leverage.

Tools. The pipe is for extra leverage if needed

Shimano type freewheel with park FR-1 spline tool

Use a big wrench and turn it anticlockwise

The second type of freewheel uses a 2 or 4 pronged removal tool (FR-6). This fits into slots on the freewheel body and then you again use the skewer to lock it in place. If you don’t do this it will simply slip out when you apply any force. Now take your courage, a big wrench and maybe that bit of pipe and unscrew the freewheel.

BMX style FR-6 four pronged tool and freewheel

Four pronged freewheel tool held in place with skewer

Freewheel removed to reveal the threads inside and on the hub

The Cassette

The cassette is what comes on most modern bikes, but it’s actually similar to the fixed sprocket as it has no mechanism in it. It’s just a series of sprockets that instead of having a thread on the inside diameter have a series of splines. There’s still a ratcheting mechanism, but now it’s in the hub. The cassette’s splines slide over mating splines on the hub mechanism and it’s kept in place by a lock ring that on Shimano cassettes is tightened using the FR-5 Shimano spline tool. This arrangement makes removal of the cassette easy as there’s no thread that is tightened by pedaling. Place the FR-5 tool in to the cassettes splines, retain it with the skewer, grip the cassette with the chain whip to stop it from rotating and use a wrench to turn the spline tool anticlockwise until the retaining ring comes loose. Then simply pull the cassette off. Some of the cogs might be individual and others locked together on a carrier, don’t worry, just don’t loose any of the single cogs.

Use the chain whip to stop the cassette from rotating and unscrew the lock ring by turning the removal tool anticlockwise with the wrench

The splines on the hub and inside the cassette body

Several emails to the web stores that sold the Neo Primato got replies that said “can’t get it with a threaded stem”.  So I went to my local De Rosa dealer to see if one could be special ordered. The dealer said it should be possible and put me on a bike fit machine to confirm that a 54cm frame was the right one for me. It felt good so I left the store with the dealer promising to check on the availability of the frame……….

Fast forward a few days and I got a disappointing email from the dealer saying that the US distributor could not get the frame with a threaded steerer. Well that was just my cue to step up my search. I’d seen a really nice Neo Primato build on Cyclofiend with a threaded stem http://www.cyclofiend.com/cc/2007/cc415-vincentkluwe1207.html and a quick email to the owner in Berlin, Dr. Vincent Kluew, got an almost immediate response. He thanked me and said that he’d got his frame from Doriano De Rosa, the son of the founder Ugo De Rosa, and that it was definitely possible to get a threaded steerer. Then he offered to call Doriano and make sure that I got the frame the way I wanted it. That was very kind and sure enough I received an email from Milan soon after saying that I could have the threaded stem and just had to include a note about it on the order. Now that’s service. Thanks Vincent and Doriano and Cristiano.

I forwarded the factory email to the dealer and went round the next day to put a 50% deposit down on a red 54cm Neo Primato frame with a 1″ threader steerer. Now all I have to do is wait six weeks for it to be delivered!

Most bikes come with one of the standard crank and chainring combinations. If it’s a road bike it might have a compact double 50/39,50/34, 53/39 or a triple 50/39/30. On specialized touring bikes you’ll find combos like 48/36/26, 46/36/24 or if they use a MTB crank something like 44/32/22. The cassette on a road bike might be a 10 speed 12-25 while for touring it might be 11-32. There are almost infinite combinations and complications which get in the way of the basic truth that a range of gears from 100″ to 20″ will satisfy most cyclists and will definitely be appropriate for a tourer. Those “gear inches” numbers I just mentioned are calculated by taking the ratio of the number of teeth on the front chain ring to the number of teeth on the rear sprocket and multiplying by the wheel diameter. So 100″ is a hard gear to push and at 80 rpm you’ll be moving at 24mph while in a 20″ gear you’ll be spinning away and at 80rpm the bike will be moving at 5mph.

I rode 48/36/24 chain rings with a 11/32 cassette for a long time giving me a range of 118″ to 20″

That would seem to be just fine, “but no – wait a minute” there are other things to consider like the gear that you ride in most of the time and how often you want to be changing gears. Also there’s the issue of cross chaining. This is where there’s a big angle in the chain and occurs when you use a big chain ring and big rear sprocket or small chain ring and little sprocket combinations. So the 48t ring on my original crank was best used with the outer 4 rear sprockets, after that the idea is to change to the middle 36t chain ring and use the middle 4 rear sprockets. This keeps the chain fairly straight, but as I like to ride around 70″ most of the time I found myself at the extreme range of the outer and middle chain rings. The 48t ring was just a bit too big and the 36t ring was just a bit too small. I also just hated changing using the front derailleur.

So it occurred to me that a 42t chain ring would be perfect for 95% of my riding and a 24t or 26t ring would be useful as a granny to haul up steep climbs. A 42/26 double would reduce front ring changes and combined with an 11/34 cassette would give me a great touring range of 103″ to 21″. Here is the resulting gearing.

The 42/26 is like a compact double, but with smaller rings to give the lower gears favoured by tourists. The smallest inner ring that fits on a conventional 110mm bolt circle diameter compact crank has 33t. So to implement this super-compact double a 110/74 double crank would be perfect, but one didn’t exist (Sugino have since come out with one http://velo-orange.blogspot.com/2009/03/taipei-cycle-show-update-3.html). I could do it on an old TA cyclotourist crank, but then the obvious hit me. Simply remove the outer ring of a 110/74 triple and put the 42t ring on the middle location and the 26t ring on the inner position. I chose 26t over 24t to stay withing the range of a compact double front derailleur, ie 50-34= 42-26= 16. I’d have to move the bottom bracket cartridge out a few mm so that the middle ring lined up with the 17t sprocket on my 11/34 rear cassette, but with a Phil Wood square taper BB that’s easy. I took the rings off my Sugino 110/74 triple and replaced them with two shinny 42t and 26t TA rings. I had to use single ring crank bolts and the front derailleur had to be mounted with a larger than usual gap to the outer ring to clear the chainstay, but it works really well and is now my default gearing for all my riding. My chain is straight in 66.7″ gear which is the gear I use to go along at 16mph all day. I move back and forth on the rear sprocket according to the terrain and climb most stuff without going down to the 26t ring.

42t and 26t "super compact" crank

Rear 11/34 cassette

Of course you have to be prepared for some strange looks from some other cyclists when they see that your outer chain ring has 42t, but you’ll know that you actually thought about your gearing rather than slavishly following the latest fad.

So 42 is the answer and the question is

“What’s the largest chain ring on your bike?”