Sunday, September 19, 2010

Brooks Professional Saddle Frame Replacement



While riding my cross bike I noticed the sudden presence of a strange clicking sound when I pedaled. When I returned home I found the frame of my MCM Selle An-Atomica modified Brooks Pro Saddle had broken.

At first I thought I would replace the saddle, but then reconsidered given the pain of breaking in a new one. Of course there is the matter of the cost of both the saddle and the MCM Selle An-An-Atomica modification.




The good news - I found that Brooks makes replacement parts for saddles readily available through its website.
The bad news - I could not find any detailed instructions on replacing the saddle frame, so I was left to my own devices.
From the Brooks Website I ordered the parts:
Quantity 1 - Professional Frame Assembly – BYB 162
Quantity 6 - Solid Copper Rivet – Large Head (16.5 MM Dia.) - BYB273


A few weeks later the parts arrived and I took on the task of removing the broken frame.

This requires carefully removal of the 6 rear rivets. I first thought about drilling them out, but decided on a more conservative go-slow approach of using a Dremel to grind off the backside of each rivet.

Using cutting wheels at about 500 RPM, I slowly removed the flared backsides of the copper rivets so as to not to build up sufficient heat to hurt the leather. It took a total of 8 cutting wheels to complete the task.





After that, it was simple to remove the rivets from the saddle with a small punch and a few light taps of the hammer.

 







 With the rivets removed, the broken rail was easily separated from the other components of the saddle. I had to do a fair amount of cleaning at this point due to the mess created by removing the rivets.  Important! - I carefully noted the position of the tension adjustment nut and then turned it so it is all the way up on the tension adjustment bolt.

After removing the broken frame, further inspection revealed a surprise! The bracket was cracked just in front of both rail attachment points. I felt lucky the saddle didn't fail in a more serious way!



Before continuing, I decided to properly do the riveting I needed a concave punch. To save time searching for one just right for the job I made one from 11mm round steel rod using a bench grinder and 9mm drill.

To finish the business end of the punch I drilled out a bit of the end of a 11cm piece of the rod with a 9mm bit and then used a bench grinder to create a taper. Note - the concave end does not need to be very deep, but just sufficient to properly mushroom the rivet shaft.








With the concave punch completed, I gathered the other tools which included a heavy hammer to be used with the concave punch, a small smooth head hammer to do the finishing work, a large 16mm brass flat-end punch, and a large engineer's vise with anvil.










After inserting the first rivet, I placed the saddle on the vise so the rivet head was perfectly flat against its anvil. Using the punch and large hammer I carefully stuck the rivet straight-on until nicely mushroomed. Basically I hit it until I felt the punch had gone as far as it would go. Then I repeated the process 5 more times.

The result compares very well to the original rivets in both size and shape. On a side note the rivets took a bit more hammer effort that I expected. Initially I was using the small hammer, but found I needed to switch to the heavier one.




With the rivets secure the next step was to finish the heads. This was the step of most concern since it would make or break the looks of the saddle.

Supporting the frame on large flat-ended brass punch head held in the vise I used the small flat head hammer to lightly hammer around the circumference of each rivet head until flush with the leather.





I found that more and lighter hammer strokes were best to shape the rivet heads and give them that hammered appearance. NOTE - Don't worry about harming the leather. It is very elastic and will just bounce back when struck.










After hammering on the rivet heads they needed a bit of polishing using the Dremel equipped with a buffing wheel and some polishing compound.











Using the position of the tension adjustment nut noted earlier I used a Brooks saddle adjustment wrench to restore the tension to the saddle.

Lastly I put a good coat of Brook's Proofide on both sides of the leather and polished the top side with a soft cloth.










Sunday, May 23, 2010

Durable Wheels for Clydesdale Cyclists

Light weight clincher wheels utilizing low spoke counts are numerous and fashionable, but they may not be the best choice Clydesdale recreational riders.

For example, I purchased Mavic's Ksyrium Elite wheel set because of its innovations in rim and hub design, light weight, quality bearings, aerodynamics, and good looks. Unfortunately, all that goodness couldn't overcome my 109Kg rider weight driving the rear wheel severely out of true just a few days into the Bicycle Tour of Colorado.

So what's a better choice for the Clydesdale? I decided I would build a wheel set optimized for (ordered from most to least important):
  1. Durability
  2. Ease of maintenance
  3. Cost
  4. Aerodynamics
  5. Weight
First, I identified spoke count as the most important factor in durability. I especially understood it would take more spokes than the 20 of the Mavic Ksyrium Elite's rear wheel to keep me from frequent visits to the truing stand. Additionally, I decided I needed to find an inherently stronger rim.

So just how many spokes and what lacing pattern to use? Instead of a more scientific approach, I just I called upon my experiences with wheels I have ridden over the years that consistently proved themselves to be durable over thousands of road miles and requiring only infrequent trips to the truing stand. Those have been wheels with the traditional 36 spokes laced in a 3-cross pattern on both drive and non-drive side.

Having decided on the number of spokes, I starting looking for a strong 36 hole rim. My own experience with and the reputation of the Velocity's Deep-V MSW clincher rim made it the obvious choice for me. The shape of this rim gives it high strength with the bonus of good aerodynamics. The fact the Deep V is available in numerous colors is an extra added bonus. To keep things simple I decided on the same rim, spoke count, and lacing for both rear and front wheel.

Now for the hubs.... I needed to select hubs that are durable and readily available in a 36 hole drilling. Adding the factors of cost and ease of maintenance I decided on Shimano 105 hubs. They are common, perform well, are nicely finished, and simple to service. OK, I admit the Ultegra hubs where probably a better choice at just $30 more.

Here's a price comparison of hub sets as of (05/23/2010):
  • Tiagra - $53
  • 105 - $133
  • Ultegra - $163
  • Durace - $440

Now for the spokes.... I am attracted to CX-Ray spokes given Sapim's claims of 3x durability over any other spoke. They also claim their spoke's oval shape provides better aerodynamics without the hassle associated with building a wheel with bladed spokes. The downside to the CX-Ray spokes is at $2.90/spoke + nipple they are almost 6x the price of a basic DT 14g stainless spoke + brass nipple costing only $0.50. With 72 spokes in the wheel set that adds up to a difference of $173! I decided the benefit of a 36 spoke count was sufficient to meet my durability requirement and chose the basic DT 14g spoke option to keep cost down. I also considered a middle ground of using a double-butted spoke for weight savings, but I decide it was not worth the 2x spoke cost. Lastly I considered mixing spokes, perhaps putting the CX-Ray spokes on the rear drive side, but decided to keep it simple.

So here is a cost summary:

Velocity Deep V Rims x 2 - $120
Shimano 105 Hubs - $133

DT 14 SS Spokes + nipples x 72 - $36

---------------------------------------------
Total Parts Cost - $289
USD


So what is the weight penalty of my Clydesdale-friendly wheel set? Using my spouse's digital kitchen scale (admittedly not the most accurate) I found the Shimano 105, Deep V, 36 DT 14g spoke wheel set to be 434g heavier than my Mavic Ksyrium Elite wheel set. That's about 1 pound.