Oh noes! Stripped the pedal thread on my bike.

MikeHunt79 · 3 Jun 2012 at 20:39

Ok, I bought some dmr v8 pedals for my bike.

When taking the old plastic pedals off, it stripped the thread in the crank on the side with chainrings.

So, it looks like I need a new set of cranks.

Now, I have no idea which ones to get. I know that I need to keep the chain line the same as the old cranks and that my bottom bracket is square taper.

Now, how do I measure the chain line and once I've measured it how do I know weather the replacement cranks will have the same chain line?

Most cranks I've seen only specify the arm length and BCD.

eXist · 3 Jun 2012 at 21:26

count the number of teeth on the 3 chain rings, you ll be fine with just that

what kind of bike was it tho if it came with plastic pedals???

touch · 3 Jun 2012 at 23:34

eXist said:
what kind of bike was it tho if it came with plastic pedals???

I'v had a couple of decent bikes with plastic pedals. Because most bikes dont come with pedals, dealers will chuck a cheap set on if you ask for them. It's not worth them losing a sale over a couple of pounds worth of pedals.

(also, he didnt actually say the old pedals came with the bike)

Jonny ///M · 4 Jun 2012 at 00:24

Depends on the model of crank fitted. Putting a Shimano crank on a bike a suntour crank came off can mess up the chain line as the square bit of the arm sits in line with the bottom chainring on the Shimano but sits below it on the suntour.

If it's a Shimano crank you can check Shimano tech docs for the suitable BB and measure the one that's on your bike.

Either way you can fire on any square taper crank with the same size teeth and adjust the front mech to get it working ok. Won't be perfect but it would work well enough for some people.

MikeHunt79 · 5 Jun 2012 at 02:36

eXist said:
count the number of teeth on the 3 chain rings, you ll be fine with just that

what kind of bike was it tho if it came with plastic pedals???

Hi, it only has 1 chainring up front, it has 40t I think.

It's an electric mountain bike, but the pedals are pretty horrible off road and the bearings are rough, hence the v8's.

Jonny ///M said:
Depends on the model of crank fitted. Putting a Shimano crank on a bike a suntour crank came off can mess up the chain line as the square bit of the arm sits in line with the bottom chainring on the Shimano but sits below it on the suntour.

If it's a Shimano crank you can check Shimano tech docs for the suitable BB and measure the one that's on your bike.

Either way you can fire on any square taper crank with the same size teeth and adjust the front mech to get it working ok. Won't be perfect but it would work well enough for some people.

Ok, here's a pic of the cranks:

They seem to be Prowheel Chariot who I have never heard of, but after a little googling, I think these are the cranks:
http://www.pro-wheel.com/prowheel/node/68

It says Chainline 43.5mm, and by the looks of it that is the same as Shimano spec double chainring cranks according to this site:

http://sheldonbrown.com/chainline.html

So I'll pick up some Shimano road cranks and I should be good to go. Thanks.

I should also add that this bike has no front mech and no room for one as the battery gets in the way, so I wanted to be sure before getting some more cranks.