Disc Brakes on a Trek 7500 Hybrid?

[clearz]

I am looking to buy disc brakes for my hybrid bike. I am not sure is it even possible as the wheels doesn't look like they are suitable to attach the discs to. Is there any way to do this without having to replace the entire wheels?
Here are some pics of the front and back wheel axles.

 

[Mak'em Lad]

I fairly new to cycling but have done quite a bit of work on my bike which is fitted with discs.

The pictures show that the wheels do not have disc ready hubs, if they did then you would see the 6 mounting holes (I don't know how to upload photos as yet but the disc ready hub can be seen on this ebay item BANKRUPT 26" FRONT+REAR RIGIDA DISC BIKE WHEELS BLACK on eBay (end time 04-Sep-10 14:44:40 BST) )

Also there does not appear to be mounting holes for the caliper on the front forks.

The answer would be No unless you were to spend 'loads of money'.

Others should be able to confirm this.

 

[dabac]

I think I see disc brake mounting tabs on the fork(where most of the braking should happen anyway), but I don't see any on the rear. There are dic brake adapters which basically clamp on to the rear dropout. Kinda ugly looking but usually reported as functional.
There once was a company that sold an adapter to turn a rim brake hub into a disc brake hub, but it required a half relace and usually strictly speaking wasn't worth it.
Besides, your front wheel has a radial lace, which is considered a no-no for driven and braked hubs.

If you are looking for bling value, forget it. There's no way the value of the bike will increase with the amount you'll have to spend to make this happen. If you truly "need" more braking power, then a front conversion would see to most of that. You might want to look at a ceramic rim as well. Ceramic rims + rim brakes are quite an improvement over regular alloy rims, although not as much as disc brakes.

 

[tafi]

You can get a disc adapter for the rear and a disc brake will attach to the front fork. You'll need new disc compatible wheels, a rear adapter, front and rear brake kits (caliper, lever, hoses, fluid and a rotor).

For what this will cost (of the same order as what your bike cost you) I can't see that you would get significant use over and above the original V-brakes (which are already pretty powerful). Discs only come into their own in variable condiditons (wet weather and lots of mud) and where serious stopping power is needed (steep declines). If you aren't going to confront those sorts of problems on a daily basis then there is no point in converting.

 

[clearz]

This is a follow up on my Thread titled
Disc Brakes on a Trek 7500 Hybrid?
http://www.cyclingforums.com/cycling-equipment/479525-disc-brakes-trek-7500-hybrid.html#post3969855

I decided not to go with disc brakes as it would be cheaper to just go for a new bike than to try and get all that would be needed to convert my bike to one suitable for discs. Instead I went for a front and back set of Shimano XTR V-Brakes

So I brought them to the local bike repair shop to get them to put them on for me and next thing I am being told that the screw size is different. I'm ****** off now after spending so much on these brakes only for my bike not to fit them. I thought all these would be standard. Is there anything I can get to make them fit. I have attached photos below so you can see the different bolt sizes.

Can anyone recommend a solution to get these brakes to fit or will I just have to send them back.

 

[dabac]

The brake arms in the pics have the brake posts still attached. These are usually left in the frame, and then only the brake arms are replaced/transferred.
The small screw you're holding in the 2nd last pic is for bolting the brake arm to the brake post, and isn't meant to go directly into the frame. Get the brake post off from your old brakes, reinstall in frame, pop the new brakes on and you should be good.
Oh, and find a new lbs, if they messed this up they shouldn't be going near bikes for money.

The red lines indicate the brake post(which should have stayed in the frame), the green lines indicate where the smaller bolt included in your kit should go, once you've gotten the brake post back in the frame. Red circle on new brake pic indicates wher brake post should go.

 

[clearz]

Hey dabac, thanks for the reply. I can't believe they told me that **** about them not fitting in the bike store (this is a big chain store also) I have took the brake leavers off including the posts. The only problem now is I have no idea how to get the screw out of the post. It wont budge.

 

[dabac]

Well, you could clean up the threads on the post/frame, get some threadlock, put the posts + old brakes back in. Then once the threadlock has cured, have another go at unscrewing the brake arms. Or use a vise grip, or preferably a vise, clamp down real hard at the round flange between the threads on the post and the brake arm - then have a go at the screws again.

The elegant way of doing it would be to find a nut with the same thread as the post, cut a slit through half the nut, thread the nut onto the post and then clamp the nut in a vise (the slit allowing it to pinch the post w/o damaging the threads) then have a go at th screw again.