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Home Forums General Discussion Chit Chat Mixed tyres and tank slap?

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  • #26773

    Robert Parton
    Participant
    • Location:
    • Bike: RE Himalayan
    • Rank: 80cc Rider

    Please respond with your guesses, thoughts or knowledge etc. it’s a bit of a long story ( below if you can be arsed reading it).

    My question is should I be riding an adventure bike with different make age and style of tyre, and if I have been is it credible to suggest it contributed to tank slap?

    My Himalayan had done about 10000km on stock Ceat tyres. I had the rear replaced with a known brand (the fitter never called as promised to discuss options). I scrubbed it in on old mountain and fillers road. It felt better on gravel and on dry seal though had a tendency to let the rear go at low speed cornering on wet seal. I proclaimed it a success “felt like a different and better bike”.

    The next week (ANZAC day) with about 800km on it I did kawhia ruapuke raglan and on the last bit of metal after 3hrs in the chair a gentle right hander ended up with unexplainable tank slap and roadside repairs required then a bit more at home. I put it down to fatigue.

    Last Monday with a couple of thousand kms on it on my standard route to work another gentle right hander on fog dampened seal. The front Ceat tyre caught a bit of paint and tank slap has left me with broken collar bone ribs and thumb after tank slap again. I haven’t had the verdict on the bike yet.

    #26776

    Eddieb
    Keymaster
    • Location:
    • Bike: Suzuki DR650 ADV
    • Rank: 1200cc Rider

    Oh Crap! I hope the breaks are all clean and no funny issues.

    I’ve only run one set of matching tyres that I can recall in about 8 years, and in that case it was with TKC-80 front and rear on my KTM 950 Adventure and the rear tyre only lasted 8 days until the belts were showing through. While I’ve run TKC-80s on the front almost exclusively over my last 6 bikes (BMW R80G/S & R100GS, KTM 950 Adventure, 2 x DR650, DR250) I’ve run all manner of different brand tyres on the back with a huge variation in sizes and profiles and not had any issues with tank slappers.

    If the new tyre had significantly steepened the steering head angle by having a much larger diameter than the tyre it replaced I would say maybe that could have contributed on a top end sports bike, but adventure bikes are pretty lazy steering by comparison and I’d be very surprised if that would be the case.
    I would be far more inclined to be looking at the front tyre and forks. Seeing if the front tyre is past it’s best or possibly under or more particularly over inflated, forks not twisted in the clamps so the wheel isn’t straight, worn steering head bearings etc. Some of this may not be possible now seeing as the bike has been bashed up.
    I’ve never heard of Ceat tyres before now so have no thoughts on them.

    #26779

    Robert Parton
    Participant
    • Location:
    • Bike: RE Himalayan
    • Rank: 80cc Rider

    Whenever I took my hands off the bars it pulled to the right. Does that indicate a problem? It was backed over while parked in October and had quite a bit of repairs in the front end. New spoke set handlebars. Don’t know what else

    #26780

    Eddieb
    Keymaster
    • Location:
    • Bike: Suzuki DR650 ADV
    • Rank: 1200cc Rider

    A lot of people don’t sit centered on the seat, usually slightly to the left of center, and our roads camber to the left to a greater or lesser degree depending on the road so some pulling off to one side is possible, though you should be able to easily mitigate it by adjusting your body weight or position. It’s been so long since I’ve tried it I can’t remember which way my bike goes.

    The handlebars definately shouldn’t shake when you let go though.

    #26806

    OldBeer
    Participant
    • Location:
    • Bike: R1200GS, DL650, DRZ250, DRZ400S,
    • Rank: 1200cc Rider

    Sad story, mend well.
    I can report:
    DL650 has matching tyres courtesy of Eddie (Mitas). No issues (nice tyres!)
    DRZ250 did not, and they got very worn to almost illegal on the way down to the south island, 1650kms – no tank slap issues. Now has matching Dunlop 605s Have olny ridden it a short distance could not tell the difference btween the old and new tyres.
    DRZ400 does not have matching tyres. Not new but some life left. Rode it 1650 kms back from SI, in all kinds of weather and conditions, no issues.
    Previous XLV750 Africa Twin – Pirelli on the front and Shinko 705 on the back, maybe 2000kms before I sold it, no issues

    I would not think that having differnt tyres front and back would cause a tank slap.

    Interesting point about taking your hands off – we have all seen the GP boys do it – So I usually do it every now and then to check my balance and whether I’m sitting central on the bike – I know I have a tendency not to, I suspect we all do a bit. The bike usually wants to go one way or the other when I let go but I can usually correct it by shifting my backside a bit. A trial and error process. The DRZ400 I’ve just got has wonky handlebars and I noticed I couldn’t move enough to keep that on line if I let go, so something not right there. None of the above produces tank slapping at any speed, but I’m not usually going fast when I do it.

    So I am picking something was out of alignment – perhaps seriously so. Sounds like your insurance company is wriggling….not good. IF it have been backed over by a car and enough damage done to require new spokes and bars, surely the forks would have been bent? Were they replaced?

    Only time I ever get tank slapping is when I’m trying to ride on soft sand – which I don’t like much for that reason.

    Good luck, whatever happens

    #26808

    Robert Parton
    Participant
    • Location:
    • Bike: RE Himalayan
    • Rank: 80cc Rider

    thanks for the replies old beer and Eddieb.

    They didn’t replace the forks as far as I know.

    The insurance company aren’t wriggling yet I’m just keen to figure out what went wrong.

    In both cases I wasn’t riding aggressively or tentatively and I’ve never experienced anything close to it on that bike from new. And after being off bikes for a few years I was seriously rusty for the first few thousand kms.

    I can’t shake the feeling that it goes back to the insurance rebuild and new rear tyre.

    As I am recuperating I’m contemplating whether I carry on riding or not (nudged by my family’s questions). It would help if I could pin down something fixable rather than writing it off to coincidence.

    Feeling like I may not be able to trust that bike again and should be looking to trade it on a dr or klr 650 who’s quirks are better known.

    Maybe the repairer would be willing to investigate for a mechanical cause, unfortunately with neither arm working I can’t get to it and poke around.

    #26819

    OldBeer
    Participant
    • Location:
    • Bike: R1200GS, DL650, DRZ250, DRZ400S,
    • Rank: 1200cc Rider

    I am no authority but i would put my money on dodgy forks before blaming a rear tyre.

    Understand the confidence thing. Only you will know if you want to hop on again but if the RE was your first bike after a long layoff i would strongly advise to try some others. I really like the 250s they are light and easy if a bit tall. Ride a KLR before you buy one. They are a big bike.

    Good luck mate. Get well soon.

    #26820

    Robert Parton
    Participant
    • Location:
    • Bike: RE Himalayan
    • Rank: 80cc Rider

    Thanks for the comments about a bike choice. My bike is ridden mon – thu all year round for work. A 60 km commute on winding rural roads. I’m not sure a 250 will deliver there though it would be fun about once a month when I go gravel riding.

    Funny thing is I was going to test ride a klr when the RE caught my eye. Never did get that test ride

    #26823

    OldBeer
    Participant
    • Location:
    • Bike: R1200GS, DL650, DRZ250, DRZ400S,
    • Rank: 1200cc Rider

    Sounds like you need to buy my CB500x 🙂 🙂 Perfect commuter bike and about the same height and weight as your RE.

    #26824

    Robert Parton
    Participant
    • Location:
    • Bike: RE Himalayan
    • Rank: 80cc Rider

    I’m interested, sent you a private message

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