Trainer Modification

A light bike doesn't replace good fitness.

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veganeric
Posts: 150
Joined: Sat Dec 11, 2010 2:25 am
Location: MN

by veganeric

I recently got my first trainer, a KK Road Machine, having used only rollers in the past. I set it up per the instructions. "Turn the tension knob until roller touches tire, then add 2 to 5 full turns. TIP: Test tire friction by sharply moving tire a 1/4 turn back and forth. Apply another 1/2 turn on adjustment knob if needed." At two turns the tire slipped easily. By four turns it felt pretty solid, but I noticed the tire (GP4000S 700x23 110PSI) was deflecting much, much more than it does riding on the road. I knew there'd be some added deflection, but wasn't expecting it to be this severe, and am thinking this is probably why trainers are notoriously hard on tires. My thought is to wrap the roller in skateboard grip tape. That should allow me to run much less tension while still getting good traction, and this should be easier on tires. I can't imagine I'm the first person to think of this, and the fact that I've never heard of it being done makes me think there must be a reason. What am I missing?

mattr
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by mattr

Grip tape will just sand the tyre surface away.
Best off getting a trainer tyre. It'll last an age.

And TBH using any decent tyre on a turbo will just render it useless on the road in virtually no time at all

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11.4
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Joined: Tue May 23, 2006 4:33 am

by 11.4

Track sprinters have had this problem continuously with KK's. The problem with a tape like that is that it shreds and comes off, or it shreds your tire. One thing about trainer tires (that they don't really tell you about) is that the rubber is a stickier compound that doesn't slip as easily as standard road treads. Being thicker as well, it lets the trainer roller sink into it a bit more for better traction.

However, you can still easily have problems on jumps or hard efforts, and lowering tire pressure is definitely not the way to fix the problem.

The best solution is to remove the contact roller on the trainer and give it to a machinist (any gunsmith can do this for you) and have some knurling machined into it. Knurling can be all kinds of intensity from lightly stippled to big sharp points -- go for something that keeps little lands on the top of each point. An incremental advantage of this approach is that we found those rollers are rarely truly concentric so they don't grip your tire evenly (leading to bad road feel and also the aforementioned slippage). The machinist can turn it perfectly concentric which can sometimes be all you need.

After trying a lot of other approaches, we don't have too many other decent solutions that don't come off rapidly or damage your tires excessively. We certainly tried every kind of covering for the contact roller we could find, and none of them really worked. You may not have the same stress on the contact point that a track sprinter does, but frankly it drove me, and others, to spend the money on a Wahoo Kickr. Having gotten one, I haven't looked back. The Kickr addresses the problem and more.

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ITTY
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Joined: Wed Apr 09, 2014 8:08 pm
Location: Bremerton, WA

by ITTY

Grip tape will definitely destroy the tire even faster, and will probably feel like junk.

I recommend getting a trainer tire. They are much more quiet, grip the metal surface well, last a lot longer, and then you don't have to burn through your expensive tires. I only turn the knob 1/2 turn after contacting the tire, which gives me a similar contact patch to what I'd get on the road, but the thread pitch may be different on my trainer. No slippage issues.

If you have an old rear wheel laying around, you can throw a crappy cassette on there and use it exclusively for the trainer, so you can easily swap wheels when you ride outside.
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veganeric
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Joined: Sat Dec 11, 2010 2:25 am
Location: MN

by veganeric

11.4, thanks! I actually am a machinist, but unfortunately am not set up to do knurling. I checked if the roller was concentric. Mine is only 0.0015" off center when mounted. Measuring the tire (held in the trainer, but without contacting the roller) I got 0.0210" total variance, so I can't image the roller is a problem. When I have some more time I think I'll pull the roller and have it knurled. I'm hesitant to get a trainer tire because I was hoping to use my power tap wheel, which is tubular. I have a couple lightly used Tufos from before I knew better that I can sacrifice on the trainer.

amber14
Posts: 1
Joined: Thu Jan 29, 2015 10:25 pm

by amber14

The best solution is to remove the contact roller on the trainer and give it to a machinist (any gunsmith can do this for you) and have some knurling machined into it. Knurling can be all kinds of intensity from lightly stippled to big sharp points -- go for something that keeps little lands on the top of each point.
An incremental advantage of this approach is that we found those rollers are rarely truly concentric so they don't grip your tire evenly (leading to bad road feel and also the aforementioned slippage). The machinist can turn it perfectly concentric which can sometimes be all you need.

7ducati
Posts: 97
Joined: Mon Oct 10, 2011 8:34 pm

by 7ducati

Have you ridden on it yet? Once you get up to speed, you won't notice any slipping. I wouldn't knurl it, that's just going to chew up your tire. Use an old tire until it blows, or get a trainer tire. Don't over think it. Thousands of people use that trainer (including me) and don't need to modify it.
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Rick
Posts: 2034
Joined: Sat Aug 29, 2009 4:30 pm

by Rick

Assuming you are just tightening the contact until the tire doesn't slip with moderate force: the extra deflection is usual and doesn't really ruin the tire too fast. I just use a heavy training tire with a heavy tube. The extra wear is to be expected and is just life.
But I have never tried a special "training tire", so they probably are superior, assuming you are willing to swap tires or have a dedicated training wheel.

nathanong87
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by nathanong87

are people with kurt kinetics really going 5 full turns holy moly. i was doing 1.5 turns when i first got it. then as my trainer tire has been wearing down... (on 3rd full off season, about 750 miles each year) , then now im 2 turns. Like why 5 turns? yal droppin' some serious watts? heavy riders? yea i can't do like 30 second all out sprints or anything without hearing some squeaks from slippage, but seated anything-duration intervals are fine and standing through zone 1-5 are usually good.

squeaks and slippage, if your tire isn't a dedicated trainer tire. i use a gatorskin, it's never rolled once outside
when my drive train is stretched, squeaks for sure
takes some time to warm up, maybe squeaks more when cold.

i dunno. Kurt kinetic has been a great trainer to me

sanrensho
Posts: 433
Joined: Tue Aug 02, 2011 5:54 pm

by sanrensho

2 full turns is enough for me on my KK. I do not get slipping or excess tire wear.

centhar
Posts: 25
Joined: Mon Feb 27, 2012 11:59 pm

by centhar

On my KK, 4 1/2 turns with a Conti GP4000s@130psi. No slippage ever and to make sure, I wipe off the tire with alcohol once a week.

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dj97223
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Joined: Sun Nov 06, 2005 7:27 pm

by dj97223

I bought a Kurt Kinetic some years ago from 1UpUSA. I followed the instructions given with the accompanying video -- maybe 3 turns, iirc. The knob broke after a few months. I called 1Up. They promptly sent me a new part, but only after saying something like, "I don't know why the video says to turn it so much. That is wrong." Since then, I have only used maybe 1 to 1.5 turns -- just enough to stop slipping/squeaking. Works great.
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numbers505
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Location: Los Angeles
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by numbers505

I do 2 full turns. It is pretty easy to make it slip if I try but once it is rolling and up to speed I don't seem to notice much of a problem.

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Butcher
Shop Owner
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Joined: Sun Jan 03, 2010 4:58 am

by Butcher

What does that have to do with rollers/trainers?

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