Modification of BMX

Original link: https://jubeny.com/2022/07/refit-of-my-road-bike-with-small-wheels/

Some time ago, I rode a mountain bike to a place more than 20 kilometers away to participate in a team building, and maintained a speed of more than 30. After returning home, I felt a little tired, so I decided to sell the mountain bike and buy a cheap road bike to commute. While browsing the merchandise, BMX re-entered my field of vision, and this time came across an outdated breed – the 451 BMX. There should be no car shop selling this kind of car now, so I can only buy a complete car from the Internet or assemble it myself. After some comparisons, I spent 3,000 yuan to buy a second-hand car.

I don’t know much about bicycle parts. Since the previous owner listed them in detail, the quality is probably not bad. In fact, the performance of the car is very good, and it is very easy to ride, although the speed is not as fast as the road bike with big wheels. Since the frame is steel, it is also a bit heavier than my road bike, 9kg according to the previous owner. With a new car, it is natural to give priority to the experience. In addition to riding to work, I also use it to climb hills on weekends.

On the first day of buying a car, I happened to pass by Toutuoling on the way. It was the first time I used a BMX to climb a hill. I thought it was because of the car, but I didn’t realize until I went to climb again. Maybe it was because my physical condition was better that day, and it had nothing to do with the BMX.

This BMX has a flat handlebar, so it is difficult to change the position of the handlebar, especially when climbing a hill, so I have the idea of ​​changing it to a curved handlebar. I have to replace some parts while modifying the handlebars. My hands-on ability is relatively poor, and it is obviously not cost-effective to ask a car shop. After hesitating for a long time, I decided to do it myself, which is a learning process.

Buy the parts needed for the modification first, most of them are enough to buy second-hand, the expenses are as follows: 50 yuan for Merida; Shimano Sora 3500 rear derailleur, 155 yuan; Sora 3500 hand change, 279 yuan; Jiawei shift brake cable Core wire tube, 128 yuan; miscellaneous handle tape, 38 yuan; miscellaneous wire cutters, 13 yuan; electrical tape, 2 yuan.

The next step is to dismantle the car, which is also an important step in getting familiar with the car. Because I thought about reusing the old line, I encountered a little difficulty in removing the line. After trying for a long time, I found a trick to pull the line out of the brake handle, and then I found that I was busy working, the required length was different, and the old line was completely useless. . I didn’t know that I needed to remove the chain until I dismantled it. I didn’t buy any tools, so I could only open the quick buckle with my bare hands, and I didn’t buy any cleaning agent, so the removed chain couldn’t be washed.

The last step is to load the car. It is relatively simple to thread the handle changer, but how to insert the handle changer into the handlebar, it took me a while to understand how to adjust the screw. The car is rim braked, and I didn’t know how to adjust it at first, thinking that clamping the cable would be enough. The hardest and most worrying part is adjusting the gear. As expected, there is no response to the gear change after the installation, so I asked the person who sold my gear. Because we traded face-to-face, we chatted a few times and felt that he understood very well.

When installing gears, you need to adjust the gear to the smallest flywheel. Although I know this, in fact, the gear is not dialed all the way. However, after re-threading it, it still didn’t work. The hand-changing brother told me that the line was not tightened. I had already pulled it hard, and the cable tube was inserted tightly, but it still felt a little loose, so I decided to go to the car shop to have the master adjust it.

After I went to the car shop, my car immediately attracted a lot of attention, and I explained the situation to the master. Since they have already come, let the master adjust it, I think so. Probably not Giant’s car, the master immediately negotiated the price with me and charged 50 yuan to adjust the speed. I’ve been to this shop many times, there are more and more mechanics, and this person is something I haven’t seen before. After adjusting the speed, I wanted him to tighten the brake cable of the rear wheel by the way, and the opening cost is 25 yuan, but because the rear caliper lacks a washer, it can’t be tightened, so there is no charge. A small section of the wire is cut off. When paying, I don’t know why the cashier lady’s attitude is not very good. Is it my delusion? The treatment I received this time was significantly different from when I came with the Giant car.

The effect of this modification is not as good as expected, and the most fatal part is that it is uncomfortable to ride. The frame of the BMX was originally small, and the posture became lower after changing to a bent handle. It was obvious that the waist and neck would hurt. Although the waist did not hurt after two days of exercise, the problem of the neck still existed. Secondly, the parts I bought are a little heavier than the original car. Although it doesn’t feel very obvious, the weight of the whole car has indeed increased. The feel of shifting doesn’t change much, but the performance of the brakes is significantly different, especially since I’m used to Ultegra’s hydraulic disc brakes. After switching to the Sora, it feels particularly hard, not as good as the brake levers. In the end, it was the bad experience that the car shop brought me, so I couldn’t help downloading Dianping to give a bad review late at night. I don’t want to go to this car shop again.

This modification cost a total of 715 yuan, which does not seem to be cheap. The parts removed from the original car can be sold for a little price, probably only the rear derailleur and shifter of the Sram X7. Maybe the price was set a little low, and many people rushed to buy it after I was hung up on Xianyu, so I decided to keep it myself, in case I want to buy a car modification someday.


Modified 451 BMX

Modified 451 BMX

This article is reprinted from: https://jubeny.com/2022/07/refit-of-my-road-bike-with-small-wheels/
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