Main page » Suspension » BMW 2-Valve » BMW Fork modification service » BMW R45 R65 R80 R100 Twinshock shorten fork tubes - Service lower fork up to 120mm
BMW R45 R65 R80 R100 Twinshock shorten fork tubes - Service lower fork up to 120mm
Send us your fork tubes and we will shorten them professionally up to 120mm. The processing time is approx. 1 week.
On our SE Concept bikes the forks are shortened by 50mm. This value has proven to be the perfect balance between driving comfort and handling during our test drives. The feeling for the front wheel is considerably improved, on winding country roads the BMW is not to be recognized again.
Use our linear fork springs specially manufactured for the BMW two-valve engines, which are supplied with preload sleeves. This allows the spring package to be easily and professionally adjusted to the desired length. (not included in delivery)
Price for one pair = 2 tubes
Attention: The original springs should not be shortened! Cutting off springs changes the spring hardness!
The price is valid if the disassembled fork tubes are sent to us. When a complete fork is delivered, the position "overhaul fork"; is added and, if desired, a set of SE fork springs for the shortened fork.
Of course you can send us gladly your complete fork, we accomplish the entire change and you receive your fork again ready for installation back.
On our SE Concept bikes the forks are shortened by 50mm. This value has proven to be the perfect balance between driving comfort and handling during our test drives. The feeling for the front wheel is considerably improved, on winding country roads the BMW is not to be recognized again.
Use our linear fork springs specially manufactured for the BMW two-valve engines, which are supplied with preload sleeves. This allows the spring package to be easily and professionally adjusted to the desired length. (not included in delivery)
Price for one pair = 2 tubes
Attention: The original springs should not be shortened! Cutting off springs changes the spring hardness!
The price is valid if the disassembled fork tubes are sent to us. When a complete fork is delivered, the position "overhaul fork"; is added and, if desired, a set of SE fork springs for the shortened fork.
Of course you can send us gladly your complete fork, we accomplish the entire change and you receive your fork again ready for installation back.
BMW Boxer shorten fork
Why shorten fork:
The original reason to shorten the forks of the BMW 2-Ventiler models was to improve the handling. The classic BMW 2V boxers are originally designed rather rear-heavy. This makes the front wheel feel and handling not really good, at faster speeds the stem becomes light and the BMW starts to lurch.
The first measure was to install new and length adjustable shocks. The original components were inherently too soft, the spring force has naturally decreased further in 30 years. In addition, these old shock absorbers did not have a well-functioning damping system. Replacing the shocks was a significant improvement, but we were not yet satisfied with SE Concept Bike.
The second measure was to lower the front end. The handling basically improved with every millimeter we lowered the fork. In the -50mm range, the feel of the front wheel was good and the handling precise. Ride comfort did not deteriorate significantly.
What happens if I shorten more? If the fork is shortened more than 50 mm, you no longer achieve any significant improvement in handling. However, comfort decreases with every millimeter. In extreme cases, when forks are shortened 120mm, there is no remaining travel. A monolever has a total travel of 175mm. If you subtract the negative travel of about 40mm, you still have 135mm left. If you shorten the fork by 120mm you have an effective travel of only 15mm.
Shortening the fork, but how?
There are two ways to shorten the BMW two-valve forks. I'll start with the professional solution favored by SE Concept Bike:
Here, the upper fork tubes (standpipe) are shortened on a lathe by the amount by which the fork is to be lowered. The corresponding layout of the fork tubes from the cut-off area, i.e. threads or grooves, is transferred back to the shortened fork tubes, i.e. reworked. Since the upper parts of the fork legs are now shorter, this also requires correspondingly shorter fork springs. The advantage of this measure is that you basically only take the positive effects, since the spring travel is largely retained.
The second option is to reduce the travel of the original damping system (lower section of the original fork) with spacer sleeves. Here, however, it is the case that with every millimeter by which you lower the fork, you also shorten the spring travel. Other fork springs are also required for this measure. For this reason, we favor lowering BMW forks by shortening the stanchions in conjunction with new spring sets.
At this point a very important note: It is strongly discouraged to shorten the original fork springs. Shortening a spring changes the spring rate. On top of that, the original springs are progressive. Where do I cut the spring? At the top, in the soft area, or at the bottom, in the hard area? We have often driven vehicles with shortened springs. The handling is poor, even dangerous on rough roads.
Why shorten fork:
The original reason to shorten the forks of the BMW 2-Ventiler models was to improve the handling. The classic BMW 2V boxers are originally designed rather rear-heavy. This makes the front wheel feel and handling not really good, at faster speeds the stem becomes light and the BMW starts to lurch.
The first measure was to install new and length adjustable shocks. The original components were inherently too soft, the spring force has naturally decreased further in 30 years. In addition, these old shock absorbers did not have a well-functioning damping system. Replacing the shocks was a significant improvement, but we were not yet satisfied with SE Concept Bike.
The second measure was to lower the front end. The handling basically improved with every millimeter we lowered the fork. In the -50mm range, the feel of the front wheel was good and the handling precise. Ride comfort did not deteriorate significantly.
What happens if I shorten more? If the fork is shortened more than 50 mm, you no longer achieve any significant improvement in handling. However, comfort decreases with every millimeter. In extreme cases, when forks are shortened 120mm, there is no remaining travel. A monolever has a total travel of 175mm. If you subtract the negative travel of about 40mm, you still have 135mm left. If you shorten the fork by 120mm you have an effective travel of only 15mm.
Shortening the fork, but how?
There are two ways to shorten the BMW two-valve forks. I'll start with the professional solution favored by SE Concept Bike:
Here, the upper fork tubes (standpipe) are shortened on a lathe by the amount by which the fork is to be lowered. The corresponding layout of the fork tubes from the cut-off area, i.e. threads or grooves, is transferred back to the shortened fork tubes, i.e. reworked. Since the upper parts of the fork legs are now shorter, this also requires correspondingly shorter fork springs. The advantage of this measure is that you basically only take the positive effects, since the spring travel is largely retained.
The second option is to reduce the travel of the original damping system (lower section of the original fork) with spacer sleeves. Here, however, it is the case that with every millimeter by which you lower the fork, you also shorten the spring travel. Other fork springs are also required for this measure. For this reason, we favor lowering BMW forks by shortening the stanchions in conjunction with new spring sets.
At this point a very important note: It is strongly discouraged to shorten the original fork springs. Shortening a spring changes the spring rate. On top of that, the original springs are progressive. Where do I cut the spring? At the top, in the soft area, or at the bottom, in the hard area? We have often driven vehicles with shortened springs. The handling is poor, even dangerous on rough roads.
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