This is where I will try to answer all of your questions behind designing the RAM and SWAN. The same pinion gearbox bicycle with 2 very different builds.
The A-Z of...
TRYING TO EXPLAIN THE EVOLVING WORLD OF MTB STANDARDS...
There are a lot of questions that all relate to manufactures moving from traditional to modern standards: Let’s look at the 1990’s XC Mountain Bike and contribution to bicycle evolution.
Simple, 1990 started with no suspension. 1999 ended with 2” for XC. Mostly 4130 Chromoly steel, 24lb weight goal, 21gears, 71deg head angle 73deg seat angle, 26x2.0 inch tyres. The 90’s saw the rise of singlespeed mountain bike with riders after a simpler bike.
As mountain biking has moved away from road cycling and material technologies have changed, there have been a few things like, dropouts, tapered headsets, 31.6 seat posts so that dropper seat posts could be used and BB92 push fit bottom brackets for the carbon frames.
These are all subtle modern "standards" that have added advantages to the standard diamond frame.
However some are will not suit every application. Flat-mount brakes have just been introduced to road bikes. While these work fine with 140 and 160mm discs on tarmac, mountain bikes need 160 and 180mm as standard to reduce brake fade, Post-mount are more appropriate for mountain biking.
Boost 148mm rear spacing is another example of a solution to a problem that only occurs if you are running Plus sizes tyres and 1x10 (or 11) setup and the ever chaning chainline and tyre clearance issues. Singlespeed is unlikely to move over to 148mm boost as the chainline does not move and the hub flanges are wider than boost in any case.
This is my A-Z of making the informed component decision in the component nightmare out there.
ADJUSTING & BELT TENSION:
Adjustable gearbox mounting plates that also tension the belt. The Belt adjustment is done by using the tensioning fob to rotate the gearbox mounting plates. These plates can be changed and come in 2 sizes, standard and +5 if you prefer a lower bottom bracket. This gives you more options to make the frame suit your riding style.
Brakes: U,V or cantilever brakes are rim brakes that worked fine until it was wet. Disc brakes give us more control and still run with a buckled rim. Disc brakes and drop bars are also possible these days. OLSEN FRAMES use 180mm Post mount disc brakes as standard.
68 or 73mm with a square tapered axle. Heavy squeaked and crank arms loosened. Hollow axle cranks lead to the development of pressfit bottom brackets. OLSEN FRAMES use BB92 as part of the structure of the frame, with the correct tolerances this offers the lightest and stiffest solution.
BELT DRIVE ADJUSTABLE DROP-OUTS:
Our belt drive system has sliding dropouts to encompass a wide range of belt ratios. OLSEN FRAMES have chainstay lengths calculated to fit 39:20T (1.95 fast) to 39:24T (1.63 low).
The "belter" dropout allows the belt to be inserted into the frame and easily tensioned. This "belter" dropout is available with a gear hanger for multi-gear setups.
WHY BELT-DRIVE THEN?
Again for versatility and purity we wanted to improve the singlespeed drivetrain by using belt-drive. Olsen Bicycles have designed all frames around belt-drive to be fitting and tension adjustment needs to be simple and easy. Gates Carbon-drive belts are the best and the Center Track belt is wider and has been designed for the high loads of singlespeed.
They are tough, lighter than a chain, will not clog, and designed to shred mud.
Gates Center Track belts we use are lightweight (under 80g each) compared to 220g for a steel chain, and they do not rust. Unlike traditional chains and gears, they don't require oil or daily maintenance. They're almost completely silent. Gates also have a tuning Smartphone ap to assist in tensioning your belt.
Belt Drive Pros:
- Belts perform extremely well in British conditions like mud, clay and wet weather.
- Gates Carbon Drive CDX belts have a great reputation for logging long distances.
- Belt drive is very low maintenance, not even needing oil.
- Gates CDX belts and sprockets are exceptionally light. Gates CDX belt keep the alignment without “worming” off the sprockets.
Gear cable and dropper post hose can be internally routed. Brakes are best run externally for maintenance reasons.
OLSEN FRAMES can fit the derailleur, however there are so many benefits from moving away from the derailleur if the design is sound. OLSEN FRAMES provide a reliable transmission alternatives to the derailleur drive-train.
The derailleur was invented in 1928 and works perfectly fine for road bikes where precision shifting is not impaired by mud sand and more mud. A lot of design and engineering has gone into improving the rear derailleur, but this system is still exposed to the elements and mud. The derailleur has become the mechanical Achilles heel when trail conditions turn bad.
- Expensive: When the chain wears out the sprockets often need changing too.
- High maintenance: Lack of gears when the cable becomes clogged with mud.
- Vulnerable: The rear mech is vulnerable to damage by hitting trail obstacles.
- Adjust shifting: Can drop the chain in between the cassette and the spokes.
DROP OUT STANDARDS:
OLSEN FRAMES fit 142/12mm maxle or Syntace X-12 dropouts are used.. Hope, Pinion, DT and Chris King all do 142mm maxle hubs, with no plans to do a 148mm singlespeed hub.
OLSEN FRAMES have elevated chainstays to allow the use of continuous runs of uni-directional (UD) carbon from the axles to the headtube. Elevated chainstays also gives the frame large tyre clearance around the chainstays and chainring. Symmetrical chainstays keeps the Carbon lay-up the same on both sides for strength and balance.
Gearboxes fit into OLSEN BICYCLES Philosophy having long-term benefits for mountain biking than an exposed rear derailleur system. Years of maintenance free cycling. 10000 quite belt-drive miles.
Both of the OLSEN FRAMES; the Ram and the Swan are the same frame design, however I have designed the frame to allow for some small changes to create a Semi-Customiseable Frame Geometry. This is why it can be both the Swan or Ram:
I can change the Reach (top tube) from between 400 - 455mm.
Head angle can be anything from 66 to 70 degrees.
Bottom bracket drop can be changed by changing the mounting plates.
GEOMETRY - LONG TRAVEL (Ram):
With a 66 or 68 degree slack head angle this frame can handle 120mm forks with 29er tyres or 140mm forks with 27.5" tyres. This makes the riding style aggressive and perfect for jumps, burms and table tops at Trail centres.
GEOMETRY - RIGID FORK (Swan):
With 68 or 70 degree head angle this from feels balanced with 470mm Axle to Crown rigid fork.
This make the bike ideal for bike packing and long distance cycling.
All mountain bikes adopted road steerers of 1” apart from Klein who oversized to reduce weight.
Gary Fisher help to push for larger steerer sizes for MTBs.
However 11/8” are not strong enough for Carbon forks. Tapered carbon steerers are the best approach. This is now a mine field of changes, however Cane Creek did a good job to cover all of the standards.
HEADTUBES FOR TAPERED STEERERS:
Why Tapered or SHIS 44 headtube options? SHIS IS44 / EC44 or IS42 / IS52 head tube?
Both allow the use of tapered steerers which allows for the best use of carbon forks. Bearing stress on the bottom headset cup is very high, so a larger 1.5" bearing will last longer than a 11/8" bearing.
OLSEN FRAMES can be made with either SHIS44 or IS42 / IS52 head tube.
SHIS IS42 / IS52 is Tapered and fits Integral headsets bearings IS42 top and IS52 bottom.
SHIS IS44/EC44 is 44mm inside top and bottom fitting Zero stack cups top and bottom and a 1.5” External bottom cup for tapered steerers.
OLSEN FRAMES have been designed with Pinion gearboxes in mind. There is more information on the Pinion website, however this is a summary of the technology that they use.
Pinion gearbox technology is based on spur gearing with two gearing sub-units connected on the output end. The combination of both gearing sub-units with their different gear pairs generates the individual gears. They are evenly spaced apart in gearshift steps that make ergonomic sense for the particular application range, depending on the type of gearbox.
Pinion does not have gear overlaps. Also, low efficiency values and chain wear are anathema to Pinion gearbox technology. Furthermore, Pinion achieve ratio bandwidths of more than 630%, meaning you can select the perfect gear for any situation. All gears can be shifted in succession or skipped in whatever order you require. It does not matter in this case whether the bicycle is moving or not. Standard hub transmissions usually have a relatively large number of components in mesh for transmitting force. With Pinion, however, force is only transmitted via two gear pairs. This technical peculiarity ensures a consistently direct and loss-free riding sensation in any gear.
These were 27.2mm, however these days with Carbon and “dropper” posts it is better to go large.
OLSEN FRAMES use the 31.6mm ID as it is both light and stiff and it is becoming the new MTB standard for both dropper and conventional seatposts.
TYRE SIZE & CHOICE:
OLSEN FRAMES incorporate two different wheel sizes, so that you have a choice of comfort or speed. This gives you two bikes or more in one and can be built into several bike set-ups ride setup.
The Ram and Swan fit both 29 x 2.4" and 27.5 x 3.0" (plus sized) tyres without affecting the handling. 27.5+ tyres give you the extra comfort braking control. 29er tyres give you the speed and roll over anything.