Bottom Bracket Research Articles

Structural Analysis and Optimization of Electric Bike Front Drive with Bottom Bracket Electric Motor

Structural Analysis and Optimization of Electric Bike Front Drive with Bottom Bracket Electric Motor

Shaking table test and numerical simulation on seismic performance of prefabricated corrugated steel utility tunnels on liquefiable ground

The seismic failure mechanism of a shallow-buried prefabricated corrugated steel utility tunnel on the liquefiable ground was investigated by the shaking table test and numerical simulation. Firstly, A scaled model of prefabricated corrugated steel utility tunnel, inside pipelines, and three kinds of brackets were designed and fabricated. The model system was then excited by two seismic ground motions on a shaking table. Various dynamic responses of the model system were measured and the interface slip of tunnel and surrounding soil was also tested by a self-designed transducer. The experimental results demonstrated that the near-tunnel soil was more likely to liquefy than the far-field soil, and the liquefied soil had a remarkable damping effect. The bottom bracket was more vulnerable to be affected by excitations with high-frequency than the suspending and standing bracket. Both the utility tunnel and the suspending bracket yielded under the mainshock, but only slight deformations were observed with the model. Finally, the tunnel-ground system was simulated numerically using the FLAC 3D program. The comparison of experimental records with simulated results was carried out for validation of research outputs. The results provide valuable insight into the seismic performance of shallow-buried underground structures and the safe design of prefabricated corrugated steel utility tunnels.

Influence of mountain bike riding velocity, braking and rider action on pedal kickback

When dealing with full suspension mountain bikes, pedal kickback is one of the main parameters used to assess the performance of rear wheel kinematics. According to the currently used theory of Kovacs, pedal kickback is the backwards rotation of the crank during the compression of the rear suspension, which mainly occurs because of elongation between the bottom bracket and the rear axle. Most bike companies try to minimize pedal kickback during kinematic design, because this phenomenon creates unwanted harshness in the suspension and negatively influences rider stability due to the backwards rotation of the crank. When riding downhill above a certain velocity (i.e., the critical velocity) without pedaling or blocking the rear wheel, the cassette will complete a forward rotation instead of a backwards rotation of the crank, which is hereinafter referred to as freewheel theory. The cassette will perform this forward rotation without affecting the rider or creating suspension harshness. The paper discusses the analytical derivation for the calculation of the linearized critical velocity and presents a multibody simulation to calculate the exact critical velocity. The existence of the critical velocity is shown through measurements with an instrumented bike during a test ride on a downhill track and through an experiment performed under idealized conditions. The test ride demonstrated the influence of the rider on the critical velocity by moving the cranks in certain riding situations, such as landing on the front wheel first or hitting large obstacles. The crank movement leads to an increased (forward rotation) or decreased (backwards rotation) critical velocity. Both riding situations are reproduced with the multibody simulation.

Production data analysis system using novel process capability indices-based circular economy

PurposeThe purpose of this paper is to establish mechanisms for process improvement so that production efficiency and product quality can be expected, and create a sustainable development in terms of circular economy.Design/methodology/approachThe authors obtain a critical value from statistical hypothesis testing, and thereby construct a process capability indices chart, which both lowers the chance of quality level misjudgment caused by sampling error and provides reference for the processes improvement in poor quality levels. The authors used the bottom bracket of bicycles as an example to demonstrate the model and methods proposed in this study.FindingsThis approach enables us to plot multiple quality characteristics, despite varying attributes and specifications, onto the same process capability analysis chart. And it therefore increases accuracy and precision to reduce rework and scrap rates (reduce), increase product availability, reduce maintenance frequency and increase reuse (reuse), increase the recycle rates of components (recycle) and lengthen service life, which will delay recovery time (recovery).Originality/valueParts manufacturers in the industry chain can upload their production data to the cloud platform. The quality control center of the bicycle manufacturer can utilized the production data analysis model to identify critical-to-quality characteristics. The platform also offers reference for improvement and adds the improvement achievements and experience to its knowledge management to provide the entire industry chain. Feedback is also given to the R&D department of the bicycle manufacturer as reference for more robust product designs, more reasonable tolerance designs, and selection criteria for better parts suppliers, thereby forming an intelligent manufacturing loop system.

Design, Modelling and Analysis of Tilted Human Powered Vehicle

Human Powered Vehicle are powered only by muscular-strength. HPV’s are moving in road, air, in and under the water. Recumbent bike is one of the type of HPV. Recumbent bike is bicycle with inclined backward seat position and the pedals and bottom bracket are front. In this paper human powered Vehicle (HPV) is designed with a new dimension and analysed. Chassis designed with aerodynamic calculation, its CAD model analysed in Ansys for strength. Fairing is analysed with CFD. So that we can develop new low weight aerodynamic fairing, and four bar tilting mechanism. New design also gives optimum gear ratio with recumbent sitting position. The tricycle has the goals of developing innovative processes and designs for a trike that can be tilted at high speeds for enhanced turning at corners and stable at very low speeds too. The objective is to improve reliability and stability by equipping the vehicle with an aerodynamic fairing such that it can outperform conventional Human Powered Vehicle in all common applications.

E-bikes for steep roads: mid drive and hub drive motor efficiency comparison

Power input, speed, and efficiency concern people when selecting a transportation means. This study compares multiple e-bikes configurations and presents to the reader scientific criteria to choose the one that fits best for non-trained cyclists, who want to use e-bikes for everyday transportation in cities with steep roads, assuring that the cyclist takes effective part of the power input. Power development, speeds, energy consumption and efficiency result from a mathematical model and experimental data. Configurations vary in motor placement, assistance level, cyclist cadence, wheel type and transmission sets. Results indicate that the motor's placement is the most determining factor in the efficiency of the entire system. Placing the motor in the bottom bracket, allows both the cyclist and the motor to range in the most efficient rpm. As efficiency for the middle drive motor is higher than the hub drive motor, energy consumption in the hub drive motor is 18% higher.

E-bikes for steep roads: mid drive and hub drive motor efficiency comparison

Power input, speed, and efficiency concern people when selecting a transportation means. This study compares multiple e-bikes configurations and presents to the reader scientific criteria to choose the one that fits best for non-trained cyclists, who want to use e-bikes for everyday transportation in cities with steep roads, assuring that the cyclist takes effective part of the power input. Power development, speeds, energy consumption and efficiency result from a mathematical model and experimental data. Configurations vary in motor placement, assistance level, cyclist cadence, wheel type and transmission sets. Results indicate that the motor's placement is the most determining factor in the efficiency of the entire system. Placing the motor in the bottom bracket, allows both the cyclist and the motor to range in the most efficient rpm. As efficiency for the middle drive motor is higher than the hub drive motor, energy consumption in the hub drive motor is 18% higher.

Measurement and Analysis of the Torsional and the Bottom Bracket Stiffness of a Bicycle Frame

The stiffness of a bicycle frame is a major factor of a bicycle performance related to safety, stability, and weight. In this study, the torsional and bottom bracket stiffness of a bicycle frame were experimentally investigated. The torsional and bottom bracket stiffness for 63 bicycle frames were evaluated and analyzed by measuring the displacement of frames. The torsional stiffness is related with turning performance and the bottom bracket stiffness is related with power transmission. The experimental results show that the average stiffness varies up to 20 % according to the frame materials and types. The torsional stiffness has a strong corelation with the bottom bracket stiffness even though they have different effects on a bicycle frame. It seems that the experimental results can be applied to the quality criteria of racing bicycles and also design standard of a bicycle frame.

Studi Pertumbuhan Rumput Laut Jenis Kotoni (Eucheuma cottonii) dengan Menggunakan Metode Kurung Dasar dan Lepas Dasar di Perairan Geger, Bali

One of the factors that define the success of seaweed is the planting methods It self. It is important because the method will directly affect the seaweed production. The main problem faced by seaweed farmer is declining the production over years. There are several reasons causing that problem, including, predator, desease and environment degradation. The purpose of this research is investigating the effectiveness of two different seaweed planting methods with the respect to the seaweed growth rate. The two methods that mentioned previously are off bottom and off bottom bracket method. The two methods are basically simillar, the first method (off bottom) is a conventional method, on the other hand, the second method was given an additional nets in order to cover the off bottom construction. The space between each seaweed planting on two different methods are defined similar, which are 25 cm. The initial planting weight was measured 100 grams. Observation was done for 42 days (6 week) and data collection was performed every 7 days on total of 10 individual seaweed each treatment. Absolute weight, daily growth rate, daily growth and specific growth rate are calculated. The data analysis will be done using F test at ? = 0.05 (SPSS 12.0). The result found that the growth rate of seaweed (Eucheuma cottoni) under off bottom bracket was not significantly different compared to the off bottom method (?= 0.476).

The effects of forward rotation of posture on computer-simulated 4-km track cycling: Implications of Union Cycliste Internationale rule 1.3.013.

The aim of this research was to indicate improvements in 4-km cycling performance that may be gained as a function of reduced frontal surface area ( A) when Union Cycliste Internationale rule 1.3.013 is contravened. In 10 male cyclists age 26 ± 2 (mean ± standard deviation) years, height 180 ± 5 cm and body mass 71 ± 6 kg, entire cycling posture was rotated forward from where the nose of the saddle was 6 cm rearward of the bottom bracket spindle (P6) to 4, 2 and 0 cm (P4, P2 and P0); contravening Union Cycliste Internationale rule 1.3.013. Using computerised planimetry, A was estimated and a forward integration model was compiled to simulate 4-km track cycling end time ( T4km) when a fixed power profile was applied. At P2, there was a significant but non-meaningful reduction compared to P6 ( p < 0.05, d < 0.02). There were small but significant reductions in A and T4km between P6 and P0; −0.007 ± 0.004 m2 and −1.40 ± 0.73 s, respectively ( p < 0.001, d = −0.259). There were no significant differences between P4 and P6 for A and T4km. These results suggest that at the most forward position (P0), a small but significant increase in 4-km performance can be expected compared to the legal position (P6). Moreover, the mean difference in T4km between P6 and P0 is greater than the winning margin at the Union Cycliste Internationale 4-km pursuit world championships four times in the previous 10 years.

An Assessment of Bicycle Frame Behaviour under Various Load Conditions Using Numerical Simulations

This paper outlines the use of a finite element model to simulate the behaviour for a standard steel bicycle frames under a range of measured load cases. These load cases include those measured both in the laboratory setting and also in the field, and include loads transmitted at key areas such as the dropouts and hub, the bottom bracket and drive, the headset and handlebars, and the seat post and saddle. The load cases analysed include static representations of dynamic bump situations which occur sporadically and also those which occur constantly or regularly such as those generated at the drive and handlebars during climbing or cruising. The resulting stresses within the bicycle are analysed in the context of frame performance relating to static and fatigue strengths and are also compared to similar load cases presented in the literature. Further research is required to understand the influence of tube profiles on frame strength, and to analyse the modes of failure for various bicycle designs and materials used under typical and extreme usage in order to understand the implications of design on safety.

The effects of forward rotation of posture on heavy intensity cycling: Implications of UCI rule 1.3.013

UCI rule 1.3.013 limits the forward displacement of the nose of the saddle to 5cm rearward of the centre of the bottom-bracket. This study tests the effects of contravening this rule on 4km laboratory time trials and highlights biomechanical and physiological responses that could be of interest to coaches and bike fitters. Ten competitive male cyclists age 26±2 (mean±SD) yrs, height 180±5 cm, body mass 71±6 kg; V I‡ O 2max 70.9±8.6 ml·kg -1 ·min -1 ) completed 4km time trials and heavy intensity bouts. Riding posture was rotated forward where the nose of the saddle was 0, 2, 4, and 6cm to the rear of the bottom bracket (P 0 , P 2 , P 4 and P 6 ). End time, power, cardiorespiratory responses, lower appendage kinematics and crank torque kinetics were measured. There was no significant effect of position on 4 km time trials completion time or power. During 4 km time trials and heavy intensity bouts , gas exchange variables and lower limb range of motion were unchanged ( P >0.05). Trunk lean angle, cardiac output and stroke volume were greater at P 6 than other positions ( P 0.05). Results indicate, contravening rule 1.3.013 does not bring about improvements to 4km laboratory TTs. The rearward shift in peak crank torque most likely occurs as a function of altered muscle activation. Haemodynamic variations are possibly related to changes in peripheral resistance at the most forward position. Further work is necessary to allude to probable improvements in aerodynamics. Â

Power-velocity curve: relevance of the SRM Ergometer for simulated cycling performance and constant duration tests

Introduction : When trying to obtain cycling performance capacity, a controlled laboratory setting is required to obtain valid and reliable results [1]. Ecological validity is important, as several studies found poor agreement between lab and field time trials [2,3]. To perform realistic time trials on an ergometer, it is important that the cyclist is able to 1) choose its own cadence, 2) that the ergometer accounts for changes in kinetic energy and 3) the ergometer accounts for the non-linear relation between air-frictional forces and velocity. The SRM Ergometer has a free mode with a gear box and a big flywheel, so requirements 1 and 2 are fulfilled. It is unknown if the brake algorithm of the ergometer is linear or non- linear and how this mimics real life cycling. The aim of the present study is therefore to determine the relationship between the mechanical power output and the velocity in the SRM ergometer compared to cycling on a velodrome. Methods : The relation between mechanical power output and velocity in incremental cycling on an SRM Ergometer (2Hz sampling rate) was determined with the ergometer set in the “Open End Test” mode, which allows the cyclist to freely choose his gear and self-select his pace. Power output and velocity were collected over 30 s intervals of steady state cycling per stage, resulting in the power-velocity curve. The SRM Ergometer was propelled using a dynamic calibration rig to simulate a pedalling cadence ranging from 60-160 rpm, with 10 rpm steps through gears 7- 12 of the Rohloff nave. The rig was attached to the crank of the SRM Ergometer via a counterbalanced double universal joint. The axle was centred at the bottom bracket of the SRM Ergometer and attached to the crank at the position of the left pedal. By upshifting gears and increasing cadence, a range of velocities and accompanying power outputs could be evaluated. The calibration rig was powered by a 3 Ph – AC electro motor with a maximum power output of 2.2 kW. Data of 2 elite track pursuit cyclists were obtained for comparison with the ergometer. Cyclist 1 rode in standard position and cyclist 2 in aerodynamic position on a 250 m indoor velodrome in Alkmaar, the Netherlands, with an air density of 1.19 and 1.20 kg.m3 respectively. The track bikes were equipped with a SRM 7 track system. Sample rate was set at 2 Hz. Two laps at six different velocities were cycled, starting at 30 km/h with an increase in velocity of 5 km/h to 55 km/h. For SRM ergometer cycling as well as for track cycling, trend lines were added based on least-squares fit, and coefficients of determination were obtained. The best fits were used to predict power output at fixed speeds between 25 and 60 km/h for the ergometer and track cyclists. From these data Pearson product-moment correlation coefficient and absolute and relative differences in power output between the ergometer and track cyclist were determined Purpose: The objective of this study was to determine if exercise mode played a part in the acute immune responses to exercise. Results : Power fit trend lines were found to resemble the best fit for the power-velocity curve for both the SRM Ergometer as well as in the real world situation (see Figure 1). This indicates that the SRM Ergometer uses a non- linear instead of a linear breaking algorithm, related to the velocity of the flywheel. The correlation for the predicted power output at fixed speeds was perfect (r=1.000) between the SRM ergometer and both cycling position on the track, with a standard error of the estimate of 1.64 and 2.96 respectively for standard and aero position. At high velocities, the SRM Ergometer required a similar power output as standard cycling but a higher power output than required in track cycling in aero position at the same velocity (see Table 1). Conclusion : The non-linear power-velocity curve of the SRM Ergometer that closely resembles the power-velocity curve of track cycling indicates that it mimics real life cycling behaviour and that it therefore could be used to simulate free ride efforts like time trials and constant duration tests to determine mean maximal power output. However, one must be cautious to use the velocity measured by the ergometer to predict field performance, as at the same power output the speed on the track is higher in aero position.

Relationship between the Pedaling Biomechanics and Strain of Bicycle Frame during Submaximal Tests

The aim of this study was to analyse the effect of forces applied to pedals and cranks on the strain imposed to an instrumented bicycle motocross (BMX) frame. Using results from a finite element analysis to determine the localisation of highest stress, eight strain gauges were located on the down tube, the seat tube and the right chain stay. Before the pedaling tests, static loads were applied to the frame during bench tests. Two pedaling conditions have been analysed. In the first, the rider was in static standing position on the pedals and applied maximal muscular isometric force to the right pedal. The second pedaling condition corresponds to three pedaling sprint tests at submaximal intensities at 150, 300 and 550 W on a cycle-trainer. The results showed that smaller strain was observed in the pedaling condition than in the rider static standing position condition. The highest strains were located in the seat tube and the right chain stay near the bottom bracket area. The maximum stress observed through all conditions was 41 MPa on the right chain stay. This stress was 11 times lower than the yield stress of the frame material (460 MPa). This protocol could help to adapt the frame design to the riders as a function of their force and mechanical power output. These results could also help design BMX frames for specific populations (females) and rider morphology.

Structure design and system integration of 3D camera platform

This article is focusing on designing a new type of high-strength, high-precision and three-dimensional (3D) parallel film shooting platform, which not only supports the cameras but also adjusts the two cameras' distance and angle manually or automatically. Firstly, the design of the head structure of the stent comprises three layers, a bottom bracket, an intermediate bracket and a top bracket. Secondly, the main part of system integration includes a communication module and a control module. Actually, in the communication module, a chip NEC infrared remote control is used as a source of remote control signals, including the information about the stepper motor, such as rotation direction, revolution per minute and working condition. In addition, the control module is based on the microcontroller stepper motor of the STC89C51, and the stepper motor is driven by a driver chip L298N, which controls the direction and the rotation angle. Finally, the related software is programmed under C language environment in Keil uVision3. Compared with the traditional platform cameras, the new camera platform has strong stiffness, high precision and a solid structure, and it can be remotely controlled to meet the requirements of various professional shooting environments.

Finite Element Analysis of Bamboo Bicycle Frame

This work looked into the finite element analysis of Bamboo frame bicycle using commonly used Computer Aided Design softwares. A solid model of the frame was created and a finite element analysis (FEA) was conducted using the ASTM standard as a guide, with appropriate mechanical properties for various sections of the bike and the joining welds. A maximum weight of 120kg was used for the weight and seat analysis, from the analysis performed, the most fragile area was identified as being the tubes near the bottom bracket, extra carbon fiber wrapping during assembly is recommended during production for the frame. Due to the nature of Nigeria’s (developing country) road, we simulated a pothole situation using a horizontal force of 1000N to the front tire. The analysis showed that the highest stress would occur nearest to the point of impact with the pothole.

Development of a multi-directional rating test method for bicycle frame stiffness

The methods for determining the bicycle frame stiffness exist in many forms. Because the stiffness measuring method is not standardized, each bicycle magazine or bicycle constructer uses his own test configuration. This leads to a wide variety of setups; they differ in many aspects such as applied load, boundary conditions and frame deflection measurement. To clarify some shortcomings in frame testing, a multi-directional rating test method for bicycle frame stiffness has been developed. The proposed test rig design considers different aspects that should be taken into account when measuring the bicycle frame stiffness.At first, it is important to eliminate perturbing side effects that influence the stiffness value of the bicycle frame. FE analysis revealed that using ‘very stiff’ boundary conditions to constrain certain degrees of freedom should be handled with the utmost caution. Using these non-rigid boundary conditions affects the bicycle frame deflection significantly. Therefore, prior to stiffness testing, the contribution of the test rig compliance should be estimated. It is advised to limit its estimated influence below 2 %. Hysteresis effects due to stick-slip and friction are avoided by omitting fixed boundary conditions and eliminating the friction force when using a pulley mechanism; if not errors up to 11 % are observed. It is recommended to use a rolling contact to constrain translation motion and to measure the force acting on the frame without other mechanisms between the force sensor and the bicycle frame. Another issue is the effect of the head tube bearing type and the preloading torque. The industrial bearings reduce the frame stiffness up to 19 % when comparing with steel bearing replicas. It is the operator’s decision to test bicycle frames with or without industrial bearings for stiffness measurements. Though, steel bearings are advised for mutual frame comparison since this avoids discussion about the differences among industrial bearings. The overall accuracy of the test result is expressed as percentage deviation on the 95 % confidence interval and includes both the influence of the operator and the sensors. To detect small changes between results from different frames, a percentage value of 2 % or less is desired.The selection of stiffness configurations is based on the major load components acting at the head tube, the bottom bracket and the rear-dropout. The bracket- and torsion stiffness are replaced with a specific classification of the test setup. The directional frame stiffness is as such assessed for individual load cases: (i) the in-plane vertical and horizontal stiffness of the bottom-bracket and rear-dropout, (ii) the transversal or out-of-plane stiffness of the bottom bracket and (iii) the torsion stiffness with or without the contribution of the rear-triangle of the bicycle frame. As such is detailed information available for the bicycle constructor to modify the design and for the cyclist when comparing the stiffness characteristics of different frame types.

The Study of How to Extrude the Special Shaft Parts into Form

In this article, it mainly describes the use of extrusion production process as an example of the special shaft. It gives us a full analysis from the structure of the product, the material problems, the key technical problems needed to be solved, blank preparation processing and the process of extrusion forming. It also introduces the blank dimensions and the calculation method of the extrusion pressure. The method of blank lubrication processing and the process of designing extrusion mould.We are not unfamiliar with the center shaft of the bike. It is one of the important parts in bicycle bottom bracket. It is also a key part to determine the quality of the bicycle. Generally speaking, materials are used is 20 steel. The roughness of the surface is moderate. But the requirement of the product precision is high. We can get it by using mechanical processing method. But it is processing and the efficiency is low. While the utilization rate of mental material is low. So the production costs high. Because the parts production patch is large and the annual production is hundreds of thousands of pieces. In my opinion, it is more reasonable for us to adopt the technology of producing the parts with the cold extrusion precision molding process. Then we can save the materials, improve the efficiency of producing parts, lower the production parts and then meet the requirement of mass production.

Load on bicycle frame during cycling with different speeds and gestures

Experiment and dynamic simulation were combined to obtain the loads on bicycle frame. A dynamic model of body-bicycle system was built in ADAMS. Then the body gestures under different riding conditions were captured by a motion analysis system. Dynamic simulation was carried out after the data of body motions were input into the simulation system in ADAMS and a series of loads that the body applied on head tube, seat pillar and bottom bracket were obtained. The results show that the loads on frame and their distribution are apparently different under various riding conditions. Finally, finite element analysis was done in ANSYS, which showed that the stress and its distribution on frame were apparently different when the frame was loaded according to the bicycle testing standard and simulation respectively. An efficient way to obtain load on bicycle frame accurately was proposed, which is significant for the safety of cycling and will also be the basis for the bicycle design of digitalization, lightening and customization.

Development of an automated cycle ergometer

Currently a substantial amount of cycling research and training is conducted in sports science laboratories utilising cycle ergometers and/or turbo trainers. These devices have been widely used within cycling research, however, they have been found to be difficult to set-up and adjust, particularly whilst in use as well as to replicate a force profile similar to that experienced when competing. This study details the development of a novel cycle ergometer that incorporates automatic bike set-up and adjustment. The ergometer was designed in accordance with a design specification developed through the use of needs analysis of elite cyclists and performance scientists. The user analysis identified a need for increased adjustability (seat height (SH), seat set back (SS), handlebar drop (HD) and handlebar reach (HBR)) and positioning accuracy, whilst maximising the stability and stiffness of the frame when conducting maximal effort trials particularly at the bottom bracket. The novel ergometer incorporates two lifting columns to provide HD adjustment from 411mm to 868mm and SH adjustment from 568mm to 928mm. The two lifting columns were mounted on two linear rails to provide horizontal adjustment of the handlebars relative to the seat, and seat relative to the bottom bracket. The motors on both the lifting columns and linear rails were fitted with HTL encoders, increasing the positioning accuracy to+/- 0.1mm. An anti-coast brake was also fitted to prevent the lifting columns or linear rails from slipping whilst in use. When comparing existing set up time, adjusting from the largest to smallest set-up, current ergometers can take up to 30minutes, whereas the new ergometer takes 8seconds. To minimise twisting of the frame during maximal effort cycling, the bottom bracket has been mounted on a 65mm x 65mm square column. Finite element analysis of the structure identified that it would remain stable whilst subjected to up to 800Nm of torque. In conclusion the development of the novel ergometer allows for greater adjustability, speed of set-up and maximise frame stability during use.