The problem with flat mount brakes
27/10/24 15:09 Filed in: Gear
My first issue with flat mount brakes was why did we require another standard?
When disc brakes came out they were mostly IS - International Standard (some back then were proprietary and meant you were stuck with whatever brake you were supplied with). IS were bad - left/right movement of the caliper required shims or filing material off - and the brakes didn't actually mount on there, rather the appropriate adaptor did, and then the caliper mounted on that adapter. Back in the IS days, I purchased a brake mount machining kit because it was essential on almost every bike's swingarm I ever worked with (forks were cast and so better - but not perfect). I've updated the kit to work with PM and flat mount brakes (thanks Park for offering the update kit) but haven't had to use it. The range of adjustments and the quality of alignment on carbon frames means using one is extremely rare. I've also machined off part of the adaptor using the tool when the frame alignment was off but there didn't appear to be much of the tab to remove to get where I needed.
Next up came PM - post mount. And PM is still how it's done on the mountain bike. PM uses a bolt on the axis of the rotor (IS was perpendicular to this axis) and oval holes in the caliper to permit some side-to-side movement in the caliper body. To move to a larger rotor is easy with an adaptor that spaces the caliper further from the axle and some longer bolts (some adaptors use 4 bolts and move the caliper backwards as well as upwards to be more compact). I like PM. Early disc road bikes were PM because flat mount hadn't come along yet.
And then flat mount came for road bikes. For the front brake using flat mount, a literally flat adaptor bolts to the threaded holes on the caliper which in turns bolts to the fork via blind threaded holes - very similar to PM, but different in that it sits right on the fork (also worth noting that flat mount works with 140 or 160 mm rotors only - PM works with 140, 160, 180, 200 and 200 and some variations like Shimano's 203 mm rotors). At the rear, however, the mounting bolts pass up through the chainstay and into the caliper. The bolts have to move with the caliper and so tiny adjustments become markedly harder than for PM adjustments. If the bolt head at all sticks to the chainstay because of paint, dirt, a non-flat surface or any reason then the caliper can be pulled into a slight angle that will cause brake rub. Even with everything set well it is easy to get a little brake rub on a flat mount system but easy to avoid this with a PM system.
One tiny issue is that the chainstays of the frame can be thin or thick. The bolts have a short threaded section, so they need to be sized to work with the frame. When I purchased my Campagnolo gruppos, I had to figure out what length bolts to order. I also ordered 2 of each thinking they were sold individually, but I got 4 of each as they are sold in pairs. Campagnolo lists sizes in 5 mm increments and one of the bikes required 49.5 mm bolts according to the brand guidance, which is 0.5 mm from the limits of the 45-50 mm bolts. I ordered them, they worked. I was slightly worried. At only a couple of Euro per bolt, it wouldn't have been the end of the world.
Now some stylish, high-end and race-oriented mountain bikes are using flat mount disc brakes. Great if you don't actually like stopping. I say that because my hardtail now has 180 mm rotors on it, my trail bike 200 mm rotors and my DH bike has 220 mm rotors. Bigger rotors are much better for heat management. Lots of hardtails had 140 mm rotors on them but I'm with Enduro magazine in thinking that the big rotor goes on the back wheel so you can speed control on steep slopes safely.
When disc brakes came out they were mostly IS - International Standard (some back then were proprietary and meant you were stuck with whatever brake you were supplied with). IS were bad - left/right movement of the caliper required shims or filing material off - and the brakes didn't actually mount on there, rather the appropriate adaptor did, and then the caliper mounted on that adapter. Back in the IS days, I purchased a brake mount machining kit because it was essential on almost every bike's swingarm I ever worked with (forks were cast and so better - but not perfect). I've updated the kit to work with PM and flat mount brakes (thanks Park for offering the update kit) but haven't had to use it. The range of adjustments and the quality of alignment on carbon frames means using one is extremely rare. I've also machined off part of the adaptor using the tool when the frame alignment was off but there didn't appear to be much of the tab to remove to get where I needed.
Next up came PM - post mount. And PM is still how it's done on the mountain bike. PM uses a bolt on the axis of the rotor (IS was perpendicular to this axis) and oval holes in the caliper to permit some side-to-side movement in the caliper body. To move to a larger rotor is easy with an adaptor that spaces the caliper further from the axle and some longer bolts (some adaptors use 4 bolts and move the caliper backwards as well as upwards to be more compact). I like PM. Early disc road bikes were PM because flat mount hadn't come along yet.
And then flat mount came for road bikes. For the front brake using flat mount, a literally flat adaptor bolts to the threaded holes on the caliper which in turns bolts to the fork via blind threaded holes - very similar to PM, but different in that it sits right on the fork (also worth noting that flat mount works with 140 or 160 mm rotors only - PM works with 140, 160, 180, 200 and 200 and some variations like Shimano's 203 mm rotors). At the rear, however, the mounting bolts pass up through the chainstay and into the caliper. The bolts have to move with the caliper and so tiny adjustments become markedly harder than for PM adjustments. If the bolt head at all sticks to the chainstay because of paint, dirt, a non-flat surface or any reason then the caliper can be pulled into a slight angle that will cause brake rub. Even with everything set well it is easy to get a little brake rub on a flat mount system but easy to avoid this with a PM system.
One tiny issue is that the chainstays of the frame can be thin or thick. The bolts have a short threaded section, so they need to be sized to work with the frame. When I purchased my Campagnolo gruppos, I had to figure out what length bolts to order. I also ordered 2 of each thinking they were sold individually, but I got 4 of each as they are sold in pairs. Campagnolo lists sizes in 5 mm increments and one of the bikes required 49.5 mm bolts according to the brand guidance, which is 0.5 mm from the limits of the 45-50 mm bolts. I ordered them, they worked. I was slightly worried. At only a couple of Euro per bolt, it wouldn't have been the end of the world.
Now some stylish, high-end and race-oriented mountain bikes are using flat mount disc brakes. Great if you don't actually like stopping. I say that because my hardtail now has 180 mm rotors on it, my trail bike 200 mm rotors and my DH bike has 220 mm rotors. Bigger rotors are much better for heat management. Lots of hardtails had 140 mm rotors on them but I'm with Enduro magazine in thinking that the big rotor goes on the back wheel so you can speed control on steep slopes safely.
Zone 1 training
18/10/24 22:58 Filed in: Riding
You should be doing more zone 1 training. If you take a graph of lactate levels against heart rate, there is a gentle increase at first which moves (sometimes with a sharp inflection point, more often without) to a steeper increase. To generate one of these curves for a rider involves a progressive test that begins easily and progresses in steady steps to failure. Lactate levels should be checked at the end of each step. Different coaching methods use different numbers of zones, but all generally recognise the area before the actual or implied inflection point as zone 1. This is where around 90% of your time on the bike should be spent.
Zone 1 time promotes efficiency at a cellular level. Zone 1 can be completely fat-fuelled. Higher zones cannot. The more time you spend where fat is the primary source of energy, the better your body gets at using fat. The more time you spend in zone 1, the more your body is encouraged to produce mitochondria. As the energy source for the cell, more is better.
Zone 1 is the only training zone that impacts all training zones. You can spend lots of time in higher zones, getting really tired and heading towards overtraining. But that training time only really impacts the region it is "in". If you train a lot at 90% (or 75% - or any above 60% which is approximately where the top of zone 1 sits) then you can improve your response at 90% with no impact anywhere else. However, training in zone 1 moves the entire curve to the right. The inflection point goes up to a higher heart rate. Everything improves by shifting to the right.
The classic error in training is to approach the easy days too hard and the hard days too easy. Mostly it produces fatigue. Progress can happen for a while, but a plateau that you can't get off will be reached. Ease up on the easy. Attack the hard.
When you are reflecting on whether your training goal of 90+% at zone 1, you need to include all your time on the bike. So, racing too. Which is difficult or impossible if you race often (and aren't a pro who spends hours in between races in zone 1).
Since I have started making almost all my commutes in zone 1, I have taken around 10% off my commute time at the same, or perhaps even lower, heart rate. Efficiency gains!
Zone 1 time promotes efficiency at a cellular level. Zone 1 can be completely fat-fuelled. Higher zones cannot. The more time you spend where fat is the primary source of energy, the better your body gets at using fat. The more time you spend in zone 1, the more your body is encouraged to produce mitochondria. As the energy source for the cell, more is better.
Zone 1 is the only training zone that impacts all training zones. You can spend lots of time in higher zones, getting really tired and heading towards overtraining. But that training time only really impacts the region it is "in". If you train a lot at 90% (or 75% - or any above 60% which is approximately where the top of zone 1 sits) then you can improve your response at 90% with no impact anywhere else. However, training in zone 1 moves the entire curve to the right. The inflection point goes up to a higher heart rate. Everything improves by shifting to the right.
The classic error in training is to approach the easy days too hard and the hard days too easy. Mostly it produces fatigue. Progress can happen for a while, but a plateau that you can't get off will be reached. Ease up on the easy. Attack the hard.
When you are reflecting on whether your training goal of 90+% at zone 1, you need to include all your time on the bike. So, racing too. Which is difficult or impossible if you race often (and aren't a pro who spends hours in between races in zone 1).
Since I have started making almost all my commutes in zone 1, I have taken around 10% off my commute time at the same, or perhaps even lower, heart rate. Efficiency gains!
Thoughts on saddle height
09/10/24 21:28 Filed in: Riding
If you want the TL:DR right now, it is that 1 mm too high can be terrible, but 1 mm too low is seldom even noticeable.
The details...
Sometimes I swear that YouTube and Facebook can hear me think. I've been having some seat-comfort issues with my Checkpoint commuting bike since I got the new frame - more than 12 months ago. It has never been quite right in that period. Meanwhile I changed the crank length on my Madone road bike necessitating a change in seat height. I hadn't changed the seat height since I assembled that bike several years ago, so I wasn't sure how to do it or exactly how much to change it by. This is perhaps where the default feed results came from?
After riding my Madone on Sunday with the saddle at very much as much the same height as the Checkpoint as I could muster, and deciding it felt a very tiny amount too high I got to thinking if that was the source of discomfort on the Checkpoint. And into my YouTube feed came a bike fitters video about how saddle height impacts on saddle comfort. Now I didn't have the symptoms of a too-high saddle he spoke of, but I still wanted to try lowering it to see if that helped things.
I had to do a few minor things to the Checkpoint and included lowering the seat in that list. I think I went down around 4 mm. I have a red mark on the post to indicate if the post was slipping (it did slip twice when new - solved with carbon grip paste and slightly more torque on the pinch bolt). I hid the red mark. So now I can't tell if I slide down, but that is about 4mm change.
On that basis of one ride to work the next morning, I think it did help. I'm still not convinced that the saddle on there is a perfect match for me, but it definitely is not a bad one.
Next thing I have to do is revisit the Madone and drop that saddle by the same amount (and also get out some car wax to shine up the portion of the post that has been hidden inside the frame for several years but is now showing).
And then ride. Ride a bunch to see if the problem has been solved.
Typically I suggest someone try a saddle for 20 hours before deciding if they like it or not. Unfortunately, I seem to need longer. Many saddles have been close. Few have been good.
Thus I expect it will take 10 or more hours to evaluate the small drop in seat height as 1-not necessary, 2-just right, 3-too much or 4-not enough.
When the saddle goes too high, the hips cannot sit squarely on the top of the saddle and reach down to both pedals through a full revolution of the cranks. Everyone favours one side, so the non-favoured side should be reaching too far and rocking a bit on the seat resulting in pain (and possibly saddle sores) on that side. This YouTube video fitter has a saddle pressure mapping device for clients and can see if a rider is evenly sat upon the saddle. He displayed a before and after map for one client where they were heavily right-favoured before and very even after. In this case not from just dropping the saddle a bit, but a whole suite of changes including the lower seat.
If you find yourself always getting sores on one side, or your hips are rocking slightly, or you are always trying to ride on the saddle nose - these are all signs of a too-high seat.
Conversely, there are no signs of a too-low seat unless you look at near-maximal power outputs where the lack of full leg extension will cost a few Watts.
So err on the side of slightly too low.
The details...
Sometimes I swear that YouTube and Facebook can hear me think. I've been having some seat-comfort issues with my Checkpoint commuting bike since I got the new frame - more than 12 months ago. It has never been quite right in that period. Meanwhile I changed the crank length on my Madone road bike necessitating a change in seat height. I hadn't changed the seat height since I assembled that bike several years ago, so I wasn't sure how to do it or exactly how much to change it by. This is perhaps where the default feed results came from?
After riding my Madone on Sunday with the saddle at very much as much the same height as the Checkpoint as I could muster, and deciding it felt a very tiny amount too high I got to thinking if that was the source of discomfort on the Checkpoint. And into my YouTube feed came a bike fitters video about how saddle height impacts on saddle comfort. Now I didn't have the symptoms of a too-high saddle he spoke of, but I still wanted to try lowering it to see if that helped things.
I had to do a few minor things to the Checkpoint and included lowering the seat in that list. I think I went down around 4 mm. I have a red mark on the post to indicate if the post was slipping (it did slip twice when new - solved with carbon grip paste and slightly more torque on the pinch bolt). I hid the red mark. So now I can't tell if I slide down, but that is about 4mm change.
On that basis of one ride to work the next morning, I think it did help. I'm still not convinced that the saddle on there is a perfect match for me, but it definitely is not a bad one.
Next thing I have to do is revisit the Madone and drop that saddle by the same amount (and also get out some car wax to shine up the portion of the post that has been hidden inside the frame for several years but is now showing).
And then ride. Ride a bunch to see if the problem has been solved.
Typically I suggest someone try a saddle for 20 hours before deciding if they like it or not. Unfortunately, I seem to need longer. Many saddles have been close. Few have been good.
Thus I expect it will take 10 or more hours to evaluate the small drop in seat height as 1-not necessary, 2-just right, 3-too much or 4-not enough.
When the saddle goes too high, the hips cannot sit squarely on the top of the saddle and reach down to both pedals through a full revolution of the cranks. Everyone favours one side, so the non-favoured side should be reaching too far and rocking a bit on the seat resulting in pain (and possibly saddle sores) on that side. This YouTube video fitter has a saddle pressure mapping device for clients and can see if a rider is evenly sat upon the saddle. He displayed a before and after map for one client where they were heavily right-favoured before and very even after. In this case not from just dropping the saddle a bit, but a whole suite of changes including the lower seat.
If you find yourself always getting sores on one side, or your hips are rocking slightly, or you are always trying to ride on the saddle nose - these are all signs of a too-high seat.
Conversely, there are no signs of a too-low seat unless you look at near-maximal power outputs where the lack of full leg extension will cost a few Watts.
So err on the side of slightly too low.
Cassette replacements
06/10/24 16:06 Filed in: Gear
It seemed (when I worked in a shop) that the average bike shop customer rode their bike until the shifting was problematic, and then took it to their bike shop for adjustment. Often that adjustment involved a new chain and cassette (sometimes chainrings too). Which is expensive.
On the flip side are the multi-chain users. These people seem to run 3 chains at a time, swapping the one on the bike frequently with one of the other two. This way one can be on the bike, one ready to go and one getting ready to go at all time.
My own approach is closer to the first than the second. I've never had great luck with multiple chains over a single cassette. As the cassette's edges wear, even if the chain-pitch isn't wearing, performance degrades. Sloppier, slower shifts. Noisy driveline.
53/16 is a favourite gear for racing. On the race bike I spend a ton of time in the 16T sprocket. So much so that it might take 40-50% of the use. Even if it doesn't end up too worn to mesh with a brand new chain, the shifting "ports" end up worn enough that shifting suffers and it gets noisy. I had one cassette that after 28000 km, it would still take a fresh chain for pitch, but it refused to actually shift it well (sometimes at all).
Thus, my approach is to use one and only one chain, but replace it before wear gets carried away and ruins the chainrings too. And then replace the cassette at the same time. I try to take care of the whole drivetrain at the maintenance/lubrication stage rather than through the rotation of chains. Ultimately it might be a bit more expensive, but everything works as expected through its life. Taken care of they last thousands of kilometres and I don't see the point in putting up with one noisy gear, one gear that doesn't quite work right or the issues of a partially worn cassette when I can have close to perfection all the time.
And in this era of excellent lubricants that double (or quadruple) chain life, the chances of wearing out the shifting ramps on the cassette before the pitch goes "bad" seems that much higher than in the past. On my commuter bike with Record I was over 12000 km with everything still shifting nicely when I sold the Record gear. That seems just fine with me.
On the flip side are the multi-chain users. These people seem to run 3 chains at a time, swapping the one on the bike frequently with one of the other two. This way one can be on the bike, one ready to go and one getting ready to go at all time.
My own approach is closer to the first than the second. I've never had great luck with multiple chains over a single cassette. As the cassette's edges wear, even if the chain-pitch isn't wearing, performance degrades. Sloppier, slower shifts. Noisy driveline.
53/16 is a favourite gear for racing. On the race bike I spend a ton of time in the 16T sprocket. So much so that it might take 40-50% of the use. Even if it doesn't end up too worn to mesh with a brand new chain, the shifting "ports" end up worn enough that shifting suffers and it gets noisy. I had one cassette that after 28000 km, it would still take a fresh chain for pitch, but it refused to actually shift it well (sometimes at all).
Thus, my approach is to use one and only one chain, but replace it before wear gets carried away and ruins the chainrings too. And then replace the cassette at the same time. I try to take care of the whole drivetrain at the maintenance/lubrication stage rather than through the rotation of chains. Ultimately it might be a bit more expensive, but everything works as expected through its life. Taken care of they last thousands of kilometres and I don't see the point in putting up with one noisy gear, one gear that doesn't quite work right or the issues of a partially worn cassette when I can have close to perfection all the time.
And in this era of excellent lubricants that double (or quadruple) chain life, the chances of wearing out the shifting ramps on the cassette before the pitch goes "bad" seems that much higher than in the past. On my commuter bike with Record I was over 12000 km with everything still shifting nicely when I sold the Record gear. That seems just fine with me.
Bike sizing
26/09/24 22:42 Filed in: Gear
I recently put up a story about chain lubricating that was inspired by a disagreement in a Facebook cycling group about best approach to chain lubrication.
Well it happened again, this time about bike size.
The Gen 2 Trek Checkpoint was (as it has been superseded now by the gen 3) a very long bike. This length prompted many to choose a size down. A question came up from a Checkpoint shopper asking for advice about sizing. Someone replied that all else being equal, you should choose the smallest frame you can fit on.
I've heard that advice so many times; lighter frame, stiffer frame, more aero... the benefits list is long.
And I completely disagree with it. I suggested that as a fitter of 20+ years experience, when in doubt, size up. Choose the largest frame you can fit on for the most comfortable experience.
Small is OK for some professional riders. They are all young, fit and have access to a support team that can assist if the small frame leads to discomfort. I suggest for anyone with typical Western lived experience, small is not going to be your best friend. It requires a certain level of flexibility, core strength, mobility and balance to achieve a happy location on a small bike. As part of my bike fitting, I've tested a lot of cyclists for flexibility and core strength. It would be fair to say that most do not present with high flexibility and high strength.
Regardless of these, for older cyclists larger is going to help out with achieving comfort. Few at 40 still retain the flexibility and strength they had at 20.
The TL:DR summary is: there's a pretty good reason that there is a "usual" size for a bike based on a person's leg measurement. Have a good reason if you want to stray from that.
Well it happened again, this time about bike size.
The Gen 2 Trek Checkpoint was (as it has been superseded now by the gen 3) a very long bike. This length prompted many to choose a size down. A question came up from a Checkpoint shopper asking for advice about sizing. Someone replied that all else being equal, you should choose the smallest frame you can fit on.
I've heard that advice so many times; lighter frame, stiffer frame, more aero... the benefits list is long.
And I completely disagree with it. I suggested that as a fitter of 20+ years experience, when in doubt, size up. Choose the largest frame you can fit on for the most comfortable experience.
Small is OK for some professional riders. They are all young, fit and have access to a support team that can assist if the small frame leads to discomfort. I suggest for anyone with typical Western lived experience, small is not going to be your best friend. It requires a certain level of flexibility, core strength, mobility and balance to achieve a happy location on a small bike. As part of my bike fitting, I've tested a lot of cyclists for flexibility and core strength. It would be fair to say that most do not present with high flexibility and high strength.
Regardless of these, for older cyclists larger is going to help out with achieving comfort. Few at 40 still retain the flexibility and strength they had at 20.
The TL:DR summary is: there's a pretty good reason that there is a "usual" size for a bike based on a person's leg measurement. Have a good reason if you want to stray from that.