Michael Hanslip Coaching

If you want to go faster, you have to pedal harder

December 2022

Air suspension volume spacers

Despite the drawbacks, air suspension is what the majority of mountain bikes use. Air is light. Air can be freely adjusted with a shock pump. These two benefits alone are responsible for why air is King.
The alternative is a coil spring. Coils are very smooth, but also heavy and to change spring rate you must change the coil.
There is another difference that is neither positive nor negative in its own right, but generally means that the bike frame has to be designed around it - that is the linear nature of a coil spring versus the progressive nature of an air spring. A 100 lb/in spring requires 100 lb of weight on it to compress it one inch. A second 100 pounds of weight will compress it a second inch. This continues until all the coils are bottomed out on each other and the spring is maximally compressed. An air spring works very differently. Compress an air spring through half of its travel and you have approximately increased the spring rate by 100% (approximately because the air chamber does not reduce to zero volume at bottom out). Compress it by another half and this happens again. Every millimetre of movement in the coil spring requires the same input as every other millimetre of movement but every millimetre of movement in the air spring is unique in the amount of input required to achieve that movement.
Downhill bikes that typically use a coil spring require the rear suspension to build in a progressive linkage for the rear end to prevent bottom out on big hits. Cross country bikes that typically use an air spring may even have a falling rate in the rear linkage to prevent the spring from ramping up too much. Some coil sprung shocks have fancy hydraulic anti-bottom-out features as well.
The design in air springs has been towards make them feel more linear; more coil-like. Increased air volume can go some way towards that. But the amount of progression any rider requires to get both a good (comfortable) feeling at their sag point (ie, just riding along) and also to not bottom out too easily varies widely between a beginner and a professional (who might well be using the same shock).
Enter the air volume spacer.
If the air chamber is quite large producing a compression ratio in the chamber of around 4:1, then beginners will be well served. They will see most of their travel used under their moderate demands on the equipment. Put that same system under a competitive professional, and the suspension will bottom out often and hard enough to cause damage. They require more ramp-up at the end. The volume spacer that goes in a RockShox fork is a plastic disc that threads onto the underside of the air chamber cap. Simply remove all the air, unthread the cap, add or subtract a token (as RockShox calls them - the Fox system is nearly identical except they snap together rather than thread together) and reassemble/reinflate. By removing some volume from the air chamber (the plastic takes up some volume in the part of the chamber that is still open at full compression - clearly it can't occupy any of the volume used by the air piston in its travel) and beginning with the same air pressure as before, the end pressure increases. Typically the difference is only from around 1/2 travel to the end.
At sag (just riding along) the fork or shock behave the same regardless of volume spacers. But in a decent hit, the air pressure increases faster after half travel and increases the resistance of the suspension to bottoming out.
I had an old Fox 32 XC fork that was designed to be like a modern fork with several spacers in it. The compression ratio was in excess of 5:1. I never achieved full travel. Over two trials (the first to try an intermediate reduction) I shortened the air piston rod (which connects the sliders movement outside the fork to the air piston movement inside the air chamber) enough to take the compression ratio down to 4.3:1. At this lower compression ratio I could occasionally bottom out the fork without that happening too often (or requiring so much air pressure that it didn't sag adequately).
Now my hardtail has a Fox 34 fork with 120 mm of travel. It came with 2 spacers installed and two more in the packaging. At the other end of the travel scale, my new Slash has a Zeb fork with 170 mm of travel. It had one spacer installed and two more in the packaging. To get full travel in both of these forks, I had to run slightly more than normal sag and zero spacers. I seem to be light on the fork across all bikes. Not that I'm super fast - I acknowledge I'm only moderately quick. But I'm a big guy and weigh a lot and I do like to ride steeper trails (where more weight ends up on the front wheel). Yet I don't require any spacers.
I've written mostly about forks, and also about suspension linkages (rear end only except for the unusual few bikes out there) - but fork and shock can be freely interchanged in this theory. They both have air chambers and they both can use spacers inside them to take up some volume and lend more bottoming out resistance to the unit. The main difference is that a fork has a 1:1 relationship between wheel travel and air chamber piston travel. They are directly connected to each other. But the shock is on a linkage that compresses the shock 1/2 to 1/3 as much as the wheel moves. A 200 mm travel DH fork has 200 mm of movement between the sliders and the stanchions. A 200 mm travel rear end on a DH bike probably uses a 75 mm travel shock (almost 3:1). While this puts more stress on the shock, it is otherwise the same.
Prior to suspension companies making all these volume spacers available and designed into so many higher end products, the go-to solution was a blob of grease placed in an out of the way corner of the air chamber. So it has always been possible to increase the compression ratio. And my physical modification of the old Fox fork demonstrates the decrease was possible too - if rather more involved.
There are also several unconventional solutions on the market. Formula suspension uses closed cell foam volume spacers. As the pressure in the chamber increases, the volume of the foam spacer decreases. This limits the ramp-up at the end to less than you'd otherwise see. Good for controlling the mid-range without overwhelming the final range of travel. There are also designed-in and aftermarket solutions with negative air chambers. If the air chamber acts upon a piston with air pressure behind it, like the close cell foam, once the chamber pressure exceeds the opposing air pressure, it will move the piston and lessen the compression ratio. Several European producers of forks use this sort of system in their own forks and the MRP Ramp Control cartridge replaces your stock air cap and spacer stack with an on-the-trail adjustable volume spacer.
The take away message from this is that regardless of how your air suspension behaves it can be modified quite simply to behave differently. If you can't imagine undertaking this challenge yourself, there are shops and people who specialise in helping with just such problems.

Fork break-in observed

If you read all these stories, then you know I recently got my long-awaited new Slash. I put a Shock-Whiz on the fork before taking her to Thredbo last week. Riding every day in the bike park is a good workout for any part, especially suspension. The Shock-Whiz began telling me I was running too much air pressure and too much compression damping - especially the non-adjustable high-speed compression setting. By the end of the week, without doing anything to the fork (except ride it) the Shock-Whiz was telling me that these things were right in the centre of the range.
The difference was the wearing in of the seals with use.
I would assume not only the fork bushings and dust seals, but also all the o-ring seals in the damping cartridge all loosened up slightly, making the fork's action smoother.
This suggests that setting up a fork shouldn't be "finalised" until it has had at least 20 hours of use. I don't know if the Zeb will continue to loosen up with further use, or if it has plateaued now.
The other thing I take away from this experiment is that I am close to what the Shock-Whiz tells me without its input. I've been adjusting suspension on vehicles (cars, motorbikes and bicycles) for a long time. I learned something it seems. The Shock-Whiz did get me to add one click of LSC before it was happy.

For anyone interested in the Shock-Whiz as a tool, I can recommend it. Even if just for observations of the suspensions activity during a ride. It notes all manner of good and bad shock behaviours during a ride (packing down in the travel, deep compression events, air time is logged, pogo behaviour, etc) which assist with dialing in the correct settings. The answers it provides are NOT definitive because there are so many end goals in the set-up matrix (soft to firm suspension feel and active to planted behaviour): perfection in one set-up window can be terrible in another one.
Lots of people borrow or hire a Shock-Whiz to do set-up on one bike, but I really think the value is longer term. It teaches riders the relationship between a click on a dial and the behaviour on the trails in subtle ways that are hard to feel.
I learned that the break-in process lasts longer than I had assumed.

Scorpion Enduro

I have been using the Scorpion XC tyre for a couple of years and really like its grip and durability. When it came time to put new tyres on the Zipp wheels for the new Slash, I chose the Scorpion Enduro. The Mixed condition (M) on the front and the Rear specific (R) on the back.
These are the same choices I made for the XC tyres and seemed suited to riding wherever and whenever riding presents itself.
After a week of riding at Thredbo I can definitely say "wow". Particularly the front one, it just hangs on like Velcro. The rear wasn't quite as amazing, but it has much less tread as a trade-off to provide low rolling resistance. Low rolling resistance is good on the XC bikes. And it might be good slogging up a big mountain for an Enduro stage on the Enduro bike. But it is NOT good in a bike park when you're trying to go quickly. The rear end sliding is fine if you're Sam Hill (he seems to revel in that), but it is distracting for me sometimes.
I think two of the "M" tyres might be optimal for all around use, but the soft (S) variation is probably perfect for Thredbo where the ground is often quite soft (dust or dirt).

Pirelli and Continental getting serious about MTB tyres is one of the best developments of recent times in the mountain bike space. I frequently rave about the Scorpion tyres in their various options and I am looking forward to someone having the Continental Kryptotal in stock so I can try those.

Bar rotation

Does anyone actually agree on how a bar is meant to be set in the stem?
Riser bars have both upsweep and backsweep (as well as rise). Shapes differ, but generally the fat central portion is dead straight to play nicely with the stem clamp. Not far beyond the stem the "rise" part happens. At the end of that riser piece, the remainder of the bar is narrower and tilted both upwards and towards the rider.
But the clamp section is round. It can be rotated through 360 degrees inside the stem clamp. Only a few of those degrees make any sense, but they can make quite a difference to how the bars feel.
I observe that my chosen position is not the same as most chosen positions. I like to put the rising section such that it rises vertically and leaving the backsweep to provide the backsweep. Most people seem to install their bars rotated more backwards than this, with some of the upsweep contributing to backsweep (and some backsweep diminishing the upsweep offered).
My new Slash is up and running with the one-piece bar and stem combo that Slashes have this season. There is no bar rolling going on there and I'm super-keen to see where it sits and how it feels.
On one bike I ran a flat bar with loads of backsweep. I rotated it such that there was some upsweep and less backsweep. While that is how I believe it should be installed, the logo ended up pointed at the front wheel rather than dead ahead. Strongly suggesting I am wrong.
Within reason, there is no wrong. Only what suits. I strongly suspect most riders don't even think about rotating their bars in the stem and just take what their mechanic gave them when the bike was assembled.
I'll report back after some riding on the Slash...

Bar Width

How wide should your handlebars be?
I don't think there is a definitive answer to this.
I've seen it suggested that one’s ideal hand spacing for push-ups is also ones ideal bar width. For me then, my actual bar width is pretty close to perfect.
I moved to Vancouver when narrow bars were all the rage. I remember seeing guys riding flash (for the time) MTBs around on the road with ultra-narrow bars and thinking they had to ride offroad to justify those narrow controls. This was a time when a 58cm wide bar was normal, and the bars I am talking about where sub-50. This was all predicated from the tree spacing on the trails being built in those days - minimal tree cutting meant narrow was necessary.
There is a trail in Whistler on the edge of the village down to one of the primary schools. That trail is called "cut yer bars" and back when it was built in about 1991, it challenged people with 58cm bars to navigate the narrow-set trees. You can clearly see where an entire row of trees has been cut out to widen the way for more modern bars, but not so far as to get away from the spirit of the track. The first time I rode it I had 75cm bars and they just fit. The last time I rode it was with 82cm bars and that's considerably more challenging.
Between the 58cm bars I used when I started on a MTB and the 82cm bars I use now was a whole series of small progressions: 64, 68, 70, 72, 75 and 78 before 82cm. Each step felt better. No step felt like I'd gone too far. And before anyone tells me I'm "over barred" let me tell you I have a 2.1m wingspan. As I wrote above, I have tried push-ups at different hand widths and 82cm is perfectly fine (I can do just as many at a narrower width, but max reps at 82cm and 74cm are the same). I haven't specifically tried wider, but I think I'm at (or very close to) my perfect max.
I like the longer lever that the wider bars provide.
I've also seen many shorter people stuck with bars too wide for them. Many will be through ignorance and the fact that many bike companies specify one bar across the size range - not suitable to anyone riding a small but possibly not wide enough for those on the extra-large. I had a student recently who was clearly struggling with her bar width. She took it back to her bike shop and they shortened the bars to a much better length.
If there is a take-away message here it is that experimenting with bar width is important to find the optimum.

Ibis Ripley

Time flies when you are stuck in a pandemic. Or something.
It seems like just a few months since I got my Ripley, but it was early 2020 before the pandemic struck. That's more than 2 years. Actually going to be three soon!
The Ripley is the first bike I've had with a Dave Weagle suspension - in this case DW link. It does what the brochure says: it doesn't bob with pedalling but it responds to terrain inputs. It does lack the plush feeling that other suspension designs have, but it doesn't seem to detract from performance.
I took the Ripley up to Thredbo once. While the Flow trail in particular doesn't have gnarly terrain and doesn't seemingly require loads of travel to navigate, at speed on the 120mm travel Ripley I felt like I might get vibrated to pieces. Jumping on the Slash instead was much more comfortable. Even tame trails at speed reward more travel with a plusher ride.
But on XC trails it rips.
It jumps well.
It climbs well.
It is pretty light.
I can (just) get a bottle under the shock into the cage down there.
For me, it replaced a full XC race bike and I don't believe it is slower anywhere but it is faster in many places. Head angle is several degrees slacker than the XC bike. Seat angle is several degrees steeper than the XC bike. The 200mm dropper post gets the seat well out of the way - giving me more leg travel than I'd get with a lesser dropper post.
I am running a 60mm stem. With the reach on this bike it is perfect when standing but a bit short when seated. I think a 90mm stem would be better when used as an XC race bike. I even have the stem, but it has a 31.8mm bore for the bars while the bars on this bike are 35mm diameter. (If it were the other way I could shim it...)
Rowney Sports indicated that most of their builds use a 140mm travel fork. The default by design on the Ripley is a 130mm fork. I read in the release info on the then-new Ripley that they'd raised the bottom bracket so that people running a 120mm fork wouldn't hit their pedals and that decided it for me to run the 120mm option. With two bigger bikes at my disposal it didn't make sense to try to upfork the Ripley and stretch its use envelope towards bigger terrain. It did make sense to downfork it and push it more XC-wards.
I should probably make a separate entry for the fork as I find the same model on two of my bikes now, but suffice to say I like both the fork and how it performs on the Ripley.
I did a full protective vinyl wrap on the Slash, but I wanted a less labour-intensive option for the Ripley. I purchased a roll of wide and thick protective tape and cut three pieces for top, down and seat tubes. That has worked well as those are the parts of the frame that get the most abuse. The outside of the chainstays would benefit from more protection, but otherwise I'm content.
The tape I used is from Effetto Mariposa. It is too thick. It might provide extra protection being 1.2mm thick, but standard 3M automotive film does a great job on thousands of bike frames. That thick it is difficult to bend on compound curves and even hard to cut cleanly.
The Ripley is an enthusiastic bike; it encourages going faster and faster and has the traction and handling to back that up. With some medium weight wheels and fast rolling tyres (1500g Bontrager carbon wheels from my Slash and Pirelli Scorpion XC M & R tyres) it feels like the bike I was after: a playful but race-worthy bike.