Steel fork advice

[redvette]

I just put a Leeds 500 watt front hub motor kit on my old Trek 7100. To take the power safely I know I'll need to change the stock aluminum suspension fork. I'd like any recommendations you may have regarding a steel replacement fork. If possible, I'd like to retain the front suspension because of the narrow rims and tires. I guess I could get a suspension seat post.

Thanks in advance for your feedback.



Tom

 

[Nova Haibike]

There is no such a thing as a steel suspension fork, except the really terrible quality ones that come on department store bikes. Just about all the name-brand forks use aluminum or magnesium lower legs, and steel or aluminum upper tubes (your Trek has steel uppers and aluminum lowers). I don't think you'll be able to find a suspension-corrected rigid fork either. So you're probably stuck using the fork you have now.

 

[harryS]

Yes, I was surprised that my Schwinn SX2000 (got it for free) had a steel suspension fork. Didn't think there was any reason to build something so heavy (and still cheap). Even though it was steel, the steerer tube was thin wall metal and had bent under the clamping force of the stem.

If you are riding the Trek7100 on pavement, and do pre-ride inspections of your torque arms, it will probably be alright. I wouldn't like it though. I do have one front drive bike on a rigid alloy fork, but it's a smaller motor than yours. Rarely get more than 250W into it. Double torque plates. I don't touch the axle nuts. Marked them with a sharpie and I can look at them to see if they get loose.

 

[redvette]

Thank you for the information. I've decided to go with a rigid steel fork, I understand that Surly makes pretty tough forks that should be a good match for the motor. I think it's the safest way to go.

 

[Nova Haibike]

I've decided to go with a rigid steel fork, I understand that Surly makes pretty tough forks

Measure the distance between the axle and fork crown, as explained HERE. You need a fork of that approximate length. My guess is the only Surly fork that may work is the Ogre. Also, every 7100 I have ever seen had a threaded headset and quill stem. If that is what your bike has, you will also need a threadless headset and stem.