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Tech letters for October 29, 2002
Edited by John Stevenson
Confounded by carbon fiber? Need to sound off about superlight stuff? Tech letters is the forum for your gear-related questions and opinions.
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Creaking Mavic Ksyriums
Crank length
MTB Downhill brakes
Washing waterproof garments
Rapid Rise
New bike choices
Once "special rubber" Handlebar tape
Pedals
Upgrading an old bike
Sizing
Sloping top tubes
Campag Hiddenset problems
Rear clusters
Top-pull for 'Cross
Creaking Mavic Ksyriums
Last time, we ran a question about creaks from Mavic Ksyrium wheels. Seems like this is a common problem, as we were inundated with comments and suggested solutions. There were way too many of them to run here, but here's a précis:
1 Tighten the quick release as hard as possible
2 Replace the quick release with one that has a stronger clamp, such as an all-steel
Shimano or Campagnolo QR.
3 Lubricate the point where the spoke and hub connect
4 Lubricate the point where the spoke and rim connect
5 (Clean and then) lubricate the axle/fork contact points
6 Roughen the inside of the dropouts lightly, with sandpaper
7 Check it's not actually the bar/stem joint that's creaking: lube if it is
8 Adjust the hub bearing cover
9 Adjust the hub bearings
10 Dismantle the hub and grease all internal surfaces
Crank length
From: Richard Rule
I was interested to read Mark Johnston's letter.
I am faced with a similar problem, but on a mountain bike. The front end of my transmission is the weak point of the bike. I was thinking about upgrading to Shimano XT cranks combined with a splined bottom bracket. XT is available in lengths up to 180 mm, whereas middle and lower range MTB cranks tend to be available in 170 and 175 mm only.
The upgrade is relatively costly, so I want to be sure to make the right choice. I am about 6' 2" tall, with about a 35.5" inside leg.
The information I have been given so far suggests that it is advisable not to choose unnecessarily long cranks.
One source takes a health standpoint, in that a relatively high rate of crank rotation (90 rpm and above) is better for training the heart and "spinning" is less likely to cause strain in the knee joints.
The other source warned me that if I have a lot of steep climbs near me, excessive crank length would leave me with the impression of "pedalling square", particularly once fatigue starts to set in. The argument put forward was that the increased length requires greater flexibility in the ankles to bring the cranks past the dead point. It was a surprise to me to hear that I would lose rather than gain efficiency when climbing.
I am not in a position to assess my pedalling rate, never having equipped a bike with the equipment to measure it.
If you have any further information, I would be interested to know.
MTB Downhill brakes
From: Stefano Babbi
I see that motorcycle brake systems have two discs for each wheel. This solution guarantees more stability, reliability and safety. Braking action can be very efficient. I think this solution can be applied to downhill bikes, for higher performance. What do you think about this, and has anyone already tried it?
Washing waterproof garments
From Michael Stenning
I have been the cheerful owner of an Altura "Dolomite" waterproof/breathable jacket. I have never machine washed it, choosing to, sensibly follow the manufacturer's instructions - hand-washing using "Soap-Flakes" or similar very soft detergent. However, my wife and I have bought a new Zanussi washing machine with what appears a very, very gentle 'hand-wash' cycle - even by my wife's standards. However, as I really want to avoid expensive mistakes, have yourselves or indeed other contributors had any experience that affirms the practicality of doing such?
Rapid Rise
From: Matt Dambrov
I disagree with everyone who says Rapid Rise is better than the old way of shifting, and I think spring tension has little to do with it. For most mountain bikers, the more crucial shifts, and the shifts for which the rider should control the cable pull, are to lower gears (larger rear cogs), since even riders with great shifting technique will ordinarily make these shifts under some pedaling pressure and at lower cadences, such as when climbing. Relying on the rear spring for these shifts makes no sense, something proven by the fact that current Rapid Rise set-ups often hesitate shifting to smaller rear cogs when climbing.
On the other hand, upshifts (to a smaller rear cog) ordinarily occur at higher cadences and under less pedal pressure. Relying on the return spring for these shifts works just fine, assuming, of course, a relatively clean cable, a new-ish spring, etc.
And to keep momentum when hitting steep transitions, sometimes you need the ability to shift down through multiple gears. No matter how fast each click is, making multiple downshifts one-by-one will cost time and momentum. These issues are of much less concern when upshifting as you accelerate downhill - gravity helps keep momentum on your side, and few can seriously argue that they can't upshift fast enough with a conventional shifter. Ok, MAYBE in a downhill race, but new XTR is not designed for downhill racing.
Just last week I hit a short steep climb next to a buddy running Rapid Rise. I passed him easily after instantly downshifting a few gears while he was clicking away madly and waiting for his rear der to catch up.
Everyone's entitled to their preferences, and maybe it'll end being a matter of personal choice. I've made my choice and am not convinced Rapid Rise is anything more than marketing hype at the expense of function, perhaps part of an eventual plan (insert ominous evil empire soundtrack) to push other drivetrain manufacturers out of the market.
Hopefully Shimano will continue to make standard shifting available. If not, this life-long Shimano user is beginning to think SRAM shifters and derailleurs are looking pretty good.
New bike choices
From: Derek D'Angelo
I am just in the middle of purchasing a new racing bicycle after being away from the sport for 10 years. At that time, there was really only one choice in frames - steel. Now with all the combinations of aluminum, carbon, titanium and steel, purchasing a top quality frame is not nearly as easy as it once was. The bike I am considering purchasing is made of Columbus Ultrafoco steel tubing with a Columbus Muscle carbon fork and rear triangle. Besides reducing the weight, what does the carbon triangle help with? Does it improve the ride? Should I consider going with an aluminum frame? If so, would a carbon rear triangle and fork make sense on an aluminum frame? There are so many choices and I just want to make the right decision.
Once "special rubber" Handlebar tape
From: David Sommerville
I noticed from pictures and articles on Cyclingnews that Once is using special bar tape on their carbon bikes.
http://www.cyclingnews.com/tech/2002/features/probikes/?id=once
http://www.cyclingnews.com/photos/2002/tech/?id=products/giant/bike
From an article about Once's Team Mechanic in Cycle Sport magazine: "During the cleaning extra care is afforded to the easy to mark white bar tape. However, the tape on the Giants is made from rubber and not cork, and cleans easily, although it isn't as soft to the touch as cork."
My question is what is the white handlebar tape?
Ok, I know it's not Cinelli, Profile, Stella, Off the Front, Tressotar, Bennoto, Deda, and any other regular companies products. Doesn't look like Pelten either.
Maybe one (or two or 50 trollers) of cyclingnews who may live in Europe, are under contract from Once to race their bikes, or got a look at the bikes at the Tour of Spain or Tour de France can help out.
One of my riding buddies got some white bar tape from France that looks similar to the pictures of the tape in the article. It resembles Trossostar Cotton Tape in thickness and texture but is defiantly made out of something else. This tape may be different than the tape mentioned in the article.
Any ideas on what kind of tape this is and where to get it?
Pedals
From: Jim Davis
Age and miles are similar, I use Speedplay stainless, with Sidi Genius 4 shoes. I have also had knee surgery, and with the play in these pedals, I have not had any knee problems, like I encountered with other fixed pedals.
Upgrading an old bike
From: Jim Watkins
Chris, I have a CAAD3 R800 with 105 8 speed that I bought in 1997. After a lot of miles and a year of racing, the 105 shifters were completely worn out and needed replacing. I decided to upgrade to Ultegra 9 speed (shifters, crankset, BB, cassette, chain). You don't need to change the derailleurs unless they are really worn. You also don't need to change the crankset (just the chainrings?) but I wanted the new Hollowtech which is supposed to be stiffer and lighter. I found the price difference between Ultegra and new 105 to be minimal but you could save a few pennies by going with a 105 crankset and BB. I shopped around on the web and found great bargains with mail order; however, I ultimately bought from a local shop 'cause he was willing to match the best web price if I paid cash (it helps if its a small shop where the owner is the chief mechanic). The upgrade works like a dream and was like getting a brand new bike.
Sizing #1
From: Travis Hartman
In reading through all the letters about frame sizing I can't help but notice the constant comparison between the pros and the rest of us mere "biking mortals".... One thing I've noticed from hours of watching coverage of the pro peloton is that there is actually a great variety of frame sizing and riding positions amongst the best bike riders in the world. True, you are not likely to see someone riding a huge frame with their bar at equal height to their saddle, and a 90mm stem, but nevertheless there are significant position/frame size variations from rider to rider. Look closely. (Take a look at the angle of Armstrong's bars and brake hoods for instance...much higher than I would ride.)
Best bike fit and position is completely dependant upon each Individual's body shape and physiology. For instance, I am a purely recreational rider by any standards when compared to the pros, and I am not particularly flexible either (I'm always working on it!), however, I ride a moderately sized frame with a very low bar height and moderately "long" reach because it is the most comfortable fit for me. In my case the reason for my position is a combination of many factors: 1) I have very long legs (femurs in particular) short torso and relatively long arms. Thus I tend to fit frames by a combo of top tube length and HEAD-TUBE height, NOT by seat-tube length since standover is never going to be an issue. 2) I have a very light build, 5'11" 137lbs., so I don't carry very much weight in my upper body, back and shoulders to support with my arms (thus contributing to the comfort of a low bar height). 3) I don't have any back problems of any kind so a low "stretched out" position doesn't aggravate any pre-existing conditions.
Some other things to consider in any contemplation of frame size/rider position (I'm speaking more to the "aesthetics of fit" here...not about everything lining up in the right place as far as saddle setback, bar height, etc...) are: In the case of seatpost showing (seatpost height), what crank length and what kind of pedals and shoes are being used can make a huge difference in the amount of post showing. Some pedals place the foot up to 2+cm from the center of the spindle...combined with a short crank length (170mm) and a shoe that uses an adapter plate for different cleat types you could have a variation of up to 3cm or greater of seatpost showing on a particular frame for the same rider! Saddles also vary as to the distance between the rails and the top of the saddle from manufacturer to manufacturer and model to model. There is also a great deal of variety in the reach and drop of different bars. Etc, etc...
All of these "little factors" should be considered as well when fitting a bike to a particular rider and riding style.
Sizing #2
From: Chris
Ditto, on the connect the dot's theme. There are way too many variables involved with fit to go with frame size alone--as long as the seat and handle bars/shifters are in a good position without compromising bike handling then who cares. With everything from John Cobb's "slammed position" to Danilo Di Luca's insanely steep seat angles it makes no sense to generalize what eventually becomes a very personal fit determined by one's riding style and physiology.
One misconception that I do take issue with is the bias against a long stem. Long stems are fine especially if they have a rise to them and may (with a rise) actually enhance one's handling (quicker more responsive) than detract. Again there are other variables involved besides comfort such as center of gravity--My experience is that if the long stem gets the riders weight too far forward then the bike becomes very unresponsive and sluggish especially under braking and emergency maneuvers. I found this to be especially true when the seat angle was steep and the saddle push as far forward as possible on the rails (for folks with small femurs). Even though a "good bio-mechanic position" may be attained-- riding "out of balance" isn't worth the comfort/"fit" benefits and could ultimately be dangerous.
Sizing #3
From: Rich and Jules
Another observation: have you noticed that lots of pros now have their handlebars excessively tilted back. This looks like an attempt to make a super small frame a bit more comfortable by bringing the hoods up.
Sloping top tubes #1
From: Chris Mathews
I have a few comments to make on sloping top tubes and I hope you have access to some hard data supporting either side of the fence.
While I am favorable to the aesthetics of a sloping top tube I would like clarification as to how this makes the bike stiffer. According to basic geometric principles the fact that the seat tube is the base for 3 triangles (2 in the rear and the main) it would appear to be the foundation for the rigidity in the frame. If we are considering lateral load placed from the leverage of the pedal stroke it would seem that the tighter the triangles become, due to shortening their base (seat tube) the more compliant the frame will be. However, if a builder were to create different attaching points for the seat stays and the top tube at the seat tube location you would increase the frames strength. The idea of the triple triangle and the location the seat stays attach to the frame comes to mind. These isolated attaching points disperse the load and require more locations to flex. In theory, this geometric spec would allow for a progressive flex in the frame.
My hypothesis: Sloping top tube provides greater lateral flex compared to a similar size standard frame. With this same logic this would be true with vertical compliance as well.
One consideration to make (and research given time/resources/connections) is this: Cannondale is very cutting edge technologically (headshock, lefty, hollowgram cranks, and aluminum research as examples) yet do not frequently jump on trendy bandwagons until the market is established or profitable (single speed mountain bikes and the re-issue of the track bike). I imagine with the grandeur of their R&D lab that they would have tested the possibilities of the sloping top tube and its strengths compared to their standard geometry frames.
If you guys have any data supporting or contradicting me I would like to know. If not, I would like to know that too. Maybe I will do this study as a thesis/project of my manufacturing MBA.
Sloping top tubes #2
From: Steve Smith
Manny Rubio asked "Why sloping top tubes?" in the Oct. 17 letters. I can give the other side of the answer to the CN editor's "... it doesn't matter." In the right application, it matters a lot. My brutally stiff Scandium-framed Wilier would be really uncomfortable were it not for the long Selcof carbon seatpost and ultra light weight seat with thin wall Ti rails. The result is that I have nearly an inch of vertical travel when planted on the rear part of the seat. The CN editor pointed out as a negative the flexibility of the long seatpost, but as it is not subject to pedaling torque, the point is moot.
I think that the key is the long carbon seat post, in my case also a small diameter 27.2 mm (more flexy). The result is a super stiff frame that is more comfortable on rough pavement than my steel De Rosa. The same flexing that makes your carbon fork more comfortable than a normal fork also can help cushion your bum.
Sloping top tubes #3
From: Philip Ganderton
From what I've seen, smaller compact frames generally have more sloping top tubes than larger compact frames. I have a Giant TCR carbon in large, and the toptube is at about 10 deg. off horizontal. It doesn't look particularly sloping. The small size of this frame has a pretty aggressive slope since the fork must still clear the wheel, there must be room for the headset and some amount of distance between bottom head race and top race, and the top-tube, down-tube joint. The point made about getting the saddle, handle bars and pedals in the right places is paramount and the only thing relevant. For me this required a Large compact frame.
Sloping top tubes #4
From: Justin M. Baxter
I think the initial response to this letter downplays the utility of compact road frames. Originally, I think companies like Giant and Specialized experimented with sloping top tubes 1) to reduce the number of production frame sizes, and 2) to produce frames that were lighter on paper. However, as we have seen, it was not the climbers that liked these bikes for the weight savings, but rather, the sprinters who preferred them for their stiffer ride when sprinting out of the saddle.
I think that's the most important distinction. If you're a powerful sprinter that mashes the cranks out of the saddle, you're going to benefit from a compact frame. If you do most of your riding seated, you won't realize a real weight savings and you'll have potentially greater seatpost flex.
Sloping top tubes #5
From: Tim McTeague
Many bikes builders, especially custom ones, are using a bit of top tube slope to achieve the correct bar height without using a lot of spacers. With the advent of threadless headsets and carbon steerer tubes you are limited in how many spacers you can use. A sloping top tube allows a taller headtube, for good bar height, and still decent standover clearance. However, I think extreme slopes, like 10-15 degrees, are mostly fashion and a cheap way for some builders to limit frame sizes by using long seatposts and stems to force a fit.
Sloping top tubes #6
From: Jay Thurston
A sloping top tube has great benefits. It does indeed provide for a stiffer rear triangle, it makes frame lighter, and more comfortable. Yep, that's right, I said more comfortable. If you have a longer seat post that is made of Ti or especially Carbon, you will notice a huge level of greater comfort than on a conventional frame. I went from a Cannondale to a sloping Cinelli, and with my carbon seatpost its like riding a plush Ti bike but with smokin' acceleration!
Sloping top tubes #7
From: Russ Williams
Your editors missed the most important reason that companies are using the sloping top tube, and it's not for looks. The real reason (and the only advantageous one) is that it allows companies to manufacture less frame sizes. If you eliminate the standover clearance from frame sizing, the next important factor to frame fit is the length of the frame. This factor can easily be modified by switching out stems, and with the threadless design stem swaps are now a simple 5 minute process. If a company only has to manufacture 5 sizes of bikes instead of 8 or 9, it saves them a tremendous amount of money. The tooling costs to make 4 or 5 more frame sizes is double what a company spends making only 5 compact sizes. Also that allows any company that uses internal lugs (common on carbon frames) to buy less sizes of the size specific lugs.
The benefit for the consumer on compact geometry frames is minimal at best, but the cost benefit to the manufacturer is huge. That in itself brings up another question of the benefit to the consumer. Does this saved money on manufacturing trickle down to better technology or cost savings to the end consumer? That is a whole other ball of wax from the manufacturer's standpoint.
Sloping top tubes #8
From: Scott Richardson
See now I disagree with the last responder. I own a custom steel sloping top tube frame and really enjoy it's ride and it's inherent design benefits (IMO). I see/feel the frame as stiffer as there is little frame deflection in sprints and really hard efforts. Yet the long seat post acts as a ride softener. So I see the sloping top tube as being able to give a lighter and much stiffer frame, in addition to offering a soft compliant ride. Materials such as Al must certainly benefit from this. With such a frame the funky seat stay design of some Al frame builders would be redundant.
But back to the original post, I think the more the slope the better....stiffer frame and more compliant. Of course carried to an extreme you begin approaching the soft-ride (tm) style of frame building. In my opinion that is going too far, but too each their own.
Sloping top tubes #9
From: Tim Gobio
I stand 5'10" and I am a recreational rider. Based on my experience with the Giant TCR ONCE team replica and Bianchi EV2 Pantani replica, the sloping top tube is more of a marketing gimmick and production short-cut. It offers no advantages in terms of handling or acceleration. It may look "racy" given its aggressive stance but the required long seat post is a source of more problems in the long-run. In the case of the Giant TCR, its carbon aero seat post is quite heavy and has a tendency to slip down and squeak. I replaced it with a U.S.E. Alien carbon seat post. This solved the slipping down issue but not the squeaking. The Bianchi EV2, which has a less severe slope, did not pose any issues but I expected more performance from the frameset.
Campag Hiddenset problems #1
From: David B. Dowling
Do not use brass as a shim. The potential galvanic corrosion will likely damage expensive components and be a greater irritant than the creaking. Try stainless steel or Teflon - same benefit without the potential for damage.
Campag Hiddenset problems #2
From: Paul Spencer
"try wrapping a few turns of ordinary plumbing tape around the expanding doo-dad before re-inserting in the steerer"
This seems like a bad idea to me. What is called plumbing tape is more correctly called teflon tape - one of the more slippery substances around. If you don't want the expander bolt to slip, coating it with teflon seem rather counterproductive, no? I would instead clean the expander bolt thoroughly with a degreaser, clean the inside of the steerer tube with a (mild) degreaser, and install it without touching either one with your fingers. If the expander is indeed too small, then I'd search out a correctly sized one; or at worst use a non-slippery shim.
Teflon tape does work on bottom brackets - in that case, the screw threads won't slip (if torqued correctly), and the teflon works by aiding (not preventing!) the small metal-on-metal motion that produces the creak. There is no more metal-to-metal contact - there's a layer of slippery stuff in between. In this application it works the same as the more commonly used grease, only it won't wash out (which is why grease works fine for a few thousand miles, but then starts creaking).
Campag Hiddenset problems #3
From: Phil Allan
Great tip on creaking bottom brackets. I got rid of my C40 because of a squealing b/b that drove me, and everyone else, crazy. One query - what exactly do you tape? Shell or B/B threads? I now ride a TCR with a campag B/B and it also sounds like a arthritic badger. Tape is much cheaper than resorting to a Royce bracket.
Rear clusters #1
From: Stig Cornelius
I do have the rear cluster 13/29 myself and it really was an advantage when riding in the mountains of Mallorca as I never was short cadence capacity even on the long climbs.
Rear clusters #2
From: Philip Bouscarle
I had a 11/25 10 speed cassette on a Bianchi SL road bike, but decided to change to a 12/29 for a trip to the Alps this Summer. I was very glad to have this at times, especially on the first section of Alpe d'Huez and the last section of Galibier. My advice is to go for it and you can always change back to the smaller cassette if you go somewhere less hilly.
Rear clusters #3
From: Douglas M Hurst
I used a 39/26 to do two L'Etape du Tours (Stage 14 in 2001 and Stage 17 in 2002). I wish in both cases that I'd had at least a 29. The difference is about 4 inches which is significant. You will probably lose full chain range shifting range unless you go to a long cage rear derailleur. Meaning you wouldn't be able to use the 53/29 (who would want to?). If you added to your chain to make that possible, the chain would be too long. Branford Bike has a good chain length calculator.But don't think you're all the sudden going to be Lance Armstrong with a 29. If you're not at the absolute minimum healthy body weight possible, attack that first. Losing 5 pounds will make you feel like a Columbian.
Top-pull for 'Cross #1
From: Karl Butler
Try using a XTR front derailleur. XTR has always (until the new 2003 stuff) run a 46-36-24 ring combination. Shimano also made rings in a 48t for XTR 5 arm cranks, so you should have no problems using this derailleur. All other Shimano MTB derailleurs are designed for 42t or 44t big rings, so XTR really is your only option. And hey, why not spoil yourself with the best?
Top-pull for 'Cross #2
From: Ryan McCormick
I wrench at a bianchi dealer and you are correct about the stock parts spec for the axis. I do not buy the mountain derailler not working with the larger chainrings bit because a shimano XT fd which can be routed top or bottom pull will handle up to a 48 chainring up front with a 12 tooth gap to the small chainring. That should take care of a 36 48 with ease. I have run this setup more than once and it is not a problem. Good luck with the cross machine, but hurry - the season is almost here.
Top-pull for 'Cross #3
From: Steve Zdawczynski
I have struggled with the problem of top pull derailleurs on cross bikes. The top pull configuration requires the use of an MTB front derailleur, but if you like to run chainrings close in size, the inner cage of the derailleur hits the smaller ring when shifting to the big ring. I have found 3 solutions. The first obvious solution is a single ring setup. For cross racing the gearing is adequate, but for training on hills you may want a wider range. The second solution is to go to a LBS that has a tool for inserting water bottle bosses into frame tubes. Put a boss on the backside of the seat tube below the derailleur, and screw on a pulley that routes the top pull cable to a road front derailier. These pulleys are available to shops. A third option is to take your MTB derailleur and saw off the extra material on the inner cage that interferes with the chainring. You won't need that material since you won't be trying to shift up out of a 3rd chainring. This option may sound crude, but if the cutting is done right it is a clean option.
Top-pull for 'Cross #4
From: Steve Hammond
The single chainring setup is popular for CX racing. Since CX involves rough courses and shouldering the bike many racers use a single ring with chainguards to help keep the chain on (almost the same idea as downhill mountain bikes). If racing is your intention then your mechanics might be onto something. If you are using the CX bike for general riding then take advantage of the top pull derailleur and give yourself some more gears. Bianchi probably specs a top pull derailleur to keep the cables out of the mud. Finally, no one is going to laugh at you if you show up at a CX race with a FD. Cyclocross is kooky enough as it is!
Top-pull for 'Cross #5
From Matt Gersib
I've been racing the same bike in the Cat 1/2 class and have had no shifting problems with the stock LX derailleur. In the past, I had issues with the chain jumping off the 36t inner ring on rough or congested barrier sections. I completely solved the problem by mounting a "jump stop" on the seattube. The model I use is from N Gear I believe, and has a stainless steel plate that physically makes it impossible for the chain to jump ship. It weighs about 30 grams, which is a small price to pay for security. I'd use it on a single-ring setup too. I can't imagine any performance advantage (other than a slight weight loss) that would come from significantly altering your current setup. Strive for optimal setup and add a jump stop would be my course of action in your situation.
Top-pull for 'Cross #6
From: Nathan Race
See if you can dig up an old-school clamp-on MTB FD like an LX or XT (better yet XTR which was used with a 48T big ring). If you can find a pre-compact version, you should be all set. Many shops might have this sort of thing laying around in a box awaiting disposal, so it should be cheap(er). Otherwise, a cheap Simano road FD should do the trick, won't be pretty but it'll shift fine. Especially if you're using friction shifters. If not, may require some fine tuning and "custom bending" of the derailleur, but I've made it work on several occasions.
Top-pull for 'Cross #7
From: Matt Long
I'm a mechanic at A & B Cycles in Springfield, MO. I'm also the owner of an S-Works C/X bike that had a similar issue--I have a solution. They are right about not using the LX front der.--not so much because of the chainring size, you could still make that work, the bigger issue is the distance from the cable anchor bolt to the arm's pivot (mountain and road derailleurs have a different pull ratio). Smart C/X makers have solved this by using a pulley below the f. der., this allows the use of a standard f. road der. You're going to make one. Quality Bicycle Products has pulleys (part FS1091)--they're cheap, $3?. To hold the pulley, I suggest an e-type bottom bracket clamp for your seat tube diameter (1 1/8 = QBP FD9000, 1 1/4 = FD9001, 1 3/8 = FD9002) This will set you back $15-20. When you put the clamp on and attach the pulley you will notice that the angle of the cable isn't perfect--I took about 2-3 mm off the threaded portion of the clamp with a grinder wheel and it was perfect. Good Luck!
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