homejomes

I had a Giant bike but over about a year the back axle broke twice. A friend gave me a Trek bike and I found today that the back axle has broken. I'm pretty sure I'm not riding it too hard, I mainly just ride around town. Any ideas on what could be making this happen?

And I only weigh about 180 so im pretty sure thats not it lol

vpiuva

7 or 8 speed rear freewheels hubs? Axle breakage was one of the reasons the switch was made to freehubs as the # cogs grew in the rear.

homejomes

Forgive me for my ignorance in wheel workins but I dont know what rear freewheels hubs means. The giant had 7 speed in the back the Trek has an 8 speed in the back.

HillRider

If you've broken that many axles on two different bikes in a relatively short time, something you are doing is really abusive. Your bikes most likely have freehubs (unless they were made before the mid-'80's) and these are very resistant to broken axles.

Badly misaligned dropouts can break axles but this is too much of a coincidence to have happened to two different bikes unless you are really hard on them.

Have a bike shop check the dropout alignment but I think it's something you are doing.

z415

That Giant 7s sounds like it has a freewheel instead of a freehub. For the most part newer bikes do have freehubs like Hillrider said, but I have seen newer (around 1999-2001) Treks and Giants on the lower end of the price spectrum with freewheels.

Free wheels has the cogs in the back as a one piece that is threaded onto the wheel while a a freehub is a system where cogs may or may not be in pieces, but instead of threading onto the hub, it kind of slide onto it and then locked on. As for terminology, the freehub is the "thing" attached to the hub that the cogs slide on.

If you are not heavy and all you do is ride around town, then broken axles could be from a badly maintained bike. Something is most likely wrong in the rear somewhere so excessive pressure is being put on the axle. Other than that, I have no clue. If what I believe is true, you can get the hub replaced at a LBS (bike shop) and let them install it. It shouldn't be that expensive and hopefully you would have no future problems.

HillRider

The OP said the Trek is 8-speed and I don't think Trek ever used 8-speed freewheels.

homejomes

Alright the Trek is a 4300, not sure what year. The rear wheel isn't the original. No idea what kind it is.

Here's a picture of the two wheels that have broken.

https://i58.photobucket.com/albums/g2...s/P6300261.jpg

What gets me is that probably the most shock i put on the back wheel is riding off sidewalk and I've got a buddy who's riding down stairs and junk on an older gt bike and he's doing fine.

Thanks guys

z415

You're right, Trek never used freewheels in their 8s, but they did in their 7s, I was trying to imply that with the whole cheaper bike thing - anyhoo I was referring to the 7s Giant he mentioned.

Sorry for the misunderstanding.

HillRider

Can you take another photo showing the hubs in more detail? Freewheel hubs and freehubs are sufficiently different that they can be told apart from appearance but the current picture doesn't show them well enough.

2372ighost

Look here.


https://www.sheldonbrown.com/gloss_e-f.html#freewheel

OneTinSloth

the OP also said the rear wheel isn't the original. we sell lots of freewheel rear wheels to folks who've had their wheels stolen and "just want something cheap to get it going again." it's not out of the realm of possibility that it IS a freewheel rear wheel.

sknhgy 

I have a Trek 820 that I bought new in 2006 that has a freewheel, and the axel broke on it once already. The LBS fixed it under warranty.

HillRider

Was it a 7-speed freewheel?

homejomes

Ok well I took the wheel in today to get a new axle and to my xurprise the axle wasnt broken. The skewer was just bent. I wouldve taken it out to look myself earlier but last time I did that a whole mess of bearrings and half axle came out which made the bike totally unrideable. So sorry for wasting anyones time. Thanks for all the replies though. Hopefully that hardcore riding to class and back wont bend another...