WAVILA

Ive got a Trek checkpoint ALR 4 but after a 5 month use daily , did i see tis cracks in spoke holes in the rear wheel so , my question is if a can make a sutitution whit a rim ALEXRIMS MD 19 from a mtb and whit the spokes an the rear hub , make a new wheel.

mtnbud

I am far from an expert, but the first thing you need to check is the size of the rim. If I looked at the right specs, your cracked rim is an 28 hole 700 c with a 17 mm width. The Alex rim would need to be 700 c 28 hole also.

You could reuse your hub, but you'd have to use new spokes. Wheel building is very tricky. It takes lots of learning and practice to do it right. (I can't do it)

It probably makes more sense to buy good pre-built wheel than to reuse your hub.

WizardOfBoz

One thing to check: WHY did the spoke holes crack? Were the nipples overtightened? Are you a big (heavy*) person? Do you ride agressively, like over curbs and potholes and tree roots? If the cracks are due to hard use, perhaps find a very strong rim to replace it.

Wheel building does present challenges, but it's not like building a rocket ship. It can be done. But as mtnbud says, a new rim should be exactly the same size as the old. The Alex RD19 comes in three different sizes: 622mm ISO (29er, 700c), 584 mm ISO (650B), and 559mm ISO (26"). If the size you have matches the old rim, you could try this.

Read up on how to do this if you try. Couple of points:
1) To take the good rim off the old wheel, remove the freewheel or cassette first (if its a rear wheel) BEFORE loosening any more spokes.
2) Easiest way to swap is to loosen (not remove) spokes from the wheel with the cracks, then tape the good rim to that wheel (make sure that the spoke holes are aligned right). Then shift the old spoke to the new spoke hole, one by one.
3) Carefully tighten the spokes, one by one and gradually
4) True the wheel.

It's a lot of work, but if you have manual dexterity you can do this. But survey the web and watch youtube and teach yourself first!

Else, there are fairly inexpensive pre-built wheels out there.

79pmooney

Did you buy the bike from a shop? Warranty? Cracked rims in 5 months shouldn't happen. Probably a poor machine build that the shop didn't check. Unless you've been thrashing the bike, cracks in the rims shouldn't be happening until years and many thousands of miles have passed. I'd take the bike back to the shop (if that's an option) before I did any wheel work.

That said - I've rebuilt many wheels. If your two rims have the same number of spokes and ERD (effective rim diameter) do the swap as outlined above. But hitting the same ERD on different make rims is striking the pot of gold. I've never gotten so lucky. (Do a search for ERD. Not hard to measure but I haven't done it for years. I'd steer you wrong.

And edit: this will be a full wheel build, make no mistake about it. Only break you get is you don't have to think out how to run the first two spokes. All the tightening, truing, art and science is exactly like doing it from scratch. (Take notes on our existing wheel, This is one example of what you do not want!) Wheel building is a great skill to have and we all started somewhere. Like said above, it's not rocket science. But don't expect to do it fast. You do now know that spoke tension is important. (It is virtually certain your current wheel flunked that test, I cannot see your wheel or pluck your spokes so I do not know if they were too loose, too tight or not of reasonably uniform tension. All of those errors can cause the cracks you see.

Ben

andreakane

All questions mentioned above are valid. And I must agree, wheel building is not for the faint of heart. If you have a knack for math and really want to DIY, I recommend following Sheldon Brown's website for wheel building to learn what's required and a step-by-step guide.

cyccommute 

New spokes probably aren’t needed, if a new rim that is either the same brand and model is used or if it has the same effective rim diameter (ERD). The problem is finding the same rim and/or the same ERD. That’s why people tend to get new spokes for a wheel rebuild.

Is the bike new to you and only 5 months old? That’s a warranty issue. If the bike isn’t new, the Alex rim may work but you’d need the ERD for the Bontrager rim that the Checkpoint. I can’t find the ERD and it’s difficult to measure on a completed wheel. You could measure the overall diameter of the wheel and then use a caliper to measure from the bead diameter to the end of the spoke nipple and then subtract that distance (times 2). It won’t be as accurate as it can be but maybe close enough.

You’ll than need to compare that to the ERD of the Alex rims before you proceed. If you are lucky, they will match. If they are within a millimeter, you will probably be okay. If they match, you can tape the rims together, loosen the spokes on the broken rim, and move them one at a time from rim to rim. Then tension.

But, if the bike is covered under warranty, it would be easier to get a replacement wheel.

Crankycrank

Trek has a 2 year warranty on wheels. I would contact Trek first.

alcjphil

If the bike is only 5 months old, this is a warranty issue. Go see your dealer

guy153

I like the Sheldon Brown instructions but worth watching this:


Full disclosure I haven't watched it myself yet but intend to. Even though I have built many wheels I'm sure I'll learn something.

steve sumner

I was once a professional wheel builder. I was building 100 wheels a week.
the strength of a wheel is dependent on the builder and not so much on the
parts used. When someone says this rim is bulletproof it's not correct,it's
the builder who made it so. when tensioning the spokes it is very inportant
to stress relieve the rim and spokes by adding a slight side pressure to the rim
at 5 or 6 points around the circumference. tighten nipples some more and repeat
do this 4 or 5 times until at full tension. you will have a much better wheel than
if you hadn't done this. hope this helps and good luck!

WAVILA

thanks for the observation ! haha i didnt notice that de number of holes in te rim.

By the way i contact Trek dealer and they make me a valid guarantee and im still waitin for my new rear wheel.